animalaquatic

'Day-Glo' Fish Shine Red Light

2008-09-18T12:43:00.000-07:00

- It was staring them in the face, but somehow generations of marine biologists have failed to notice that a lot of fish in the sea glow a fluorescent red, according to a study published Monday.

This unheralded talent for neon-like crimson displays is more than a curiosity, and is sure to create waves -- and a bit of embarrassment -- among ichthyologists, as fish experts are called.

It has long been axiomatic that red light is simply not part of the mental universe of marine fish because the sunlight's longest visible wavelengths do not penetrate below a depth of 30 feet.

A fire-engine red diving suit at 65 feet, for example, will appear dark grey or black to anyone -- or any fish -- that happen to be in the vicinity.

Dive far enough beneath the surface, and there is simply no red to be seen.

This foreshortening of the color spectrum under the waves was also assumed to correspond to a narrowed field of vision in fish, said the study's lead researcher in an interview.

"The general consensus, which dominated fish literature for 20 or 30 years, was that fish don't see red very well or at all," explained Nico Michiels, a researcher at the University of Tubingen in Germany.

From an evolutionary standpoint, in other words, why develop a skill that you will never be able to use?

But conventional wisdom, it seems, was flat-out wrong.

"We have been blinded, literally, by the blue-green light that is available on reefs in the daytime," said Michiels.

At least 32 species of reef fish -- including pygmy gobies and some wrasses -- can shine like a red Christmas bulb, not by reflecting sunlight but by emitting their own, the study found.

Dissection revealed that the fluorescence originates in guanine crystals, a chemical compound that is added to nail polish and car paint to give added luster.

And because the light is coming from the fish themselves, it remains visible at depth and is easily seen -- but only at close distances.

Michiels and his colleagues saw the light, as it were, by accident.

Looking through a filter while scuba diving that blocked out the brighter green and blue light waves, leaving only red ones, they suddenly saw a whole universe of sea creatures glowing various hues of cherry, crimson, ruby and rust.

"Besides fish, there are lots of fluorescent organisms on the reef, including algae, coral and other small organisms," Michiels said.

That some fish glow is certain, and was confirmed using spectrometry in laboratory experiments. It is also very likely that many can see red perfectly well, and do so for a reason.

One possibility is that they emit the color -- visible only within a small circumference -- as a means of intimate communication, perhaps for mating or to signal danger.

There is also evidence that turning red could serve as a kind of camouflage.

"It may seem strange, using fluorescence to make yourself invisible," Michiels said. "But fish that sit on a reef have a lot of fluorescence around them, so they blend in."

The next step is to figure out how day-glo fish might use their color-generating power to exchange information. Adapting techniques proven in other experiments with fish, Michiels is creating an environment in which fish can court each other via video.

By controlling which part of the color spectrum the fish can see, the researchers will seek to verify that some fish do, indeed, see red.

Antarctic Krill Found at Crushing Depths

2008-09-15T06:15:00.000-07:00

Hearty Prey

- Scientists have discovered Antarctic krill living and feeding at crushing depths of 3,000 meters (9,800 feet) in waters around the Antarctic Peninsula, according to a study released Monday.

Until now the shrimp-like crustaceans were thought to only live within several hundred meters (yards) of the ocean surface, the study said.

The discovery radically changes the scientific understanding of the major food source for marine animals including fish, squid, penguins, seals and whales, said the study, published in the journal Current Biology.

"Most krill make their living in the ocean's surface waters," said Andrew Clark of the British Antarctic Survey.

"It was a surprise to observe actively feeding adult krill--including females that were apparently ready to spawn--close to the seabed in deep waters."

Antarctic krill feed on tiny phytoplankton and live in schools, called swarms, sometimes reaching densities of 10,000 individuals.

A key link in the Antarctic food chain, they grow to lengths of six centimeters (2.4 inches) and weigh up to two grams (0.7 ounces). They have a lifespan of up to eight to ten years.

Researchers from the British Antarctic Survey and the National Oceanography Center in Southampton used a deep-diving, remotely operated vehicle to film the krill in the nearly pitch-black depths.

Antarctic Warming Creating Predator 'Smorgasbord'

2008-09-15T06:14:00.000-07:00

- Global warming is setting the stage for an invasion of predators on the sea floor around Antarctica, the likes of which have not been there for more than 40 million years.

Back in the late Eocene epoch, predatory animals such as sharks and crabs were driven away from Antarctic depths when the continent and its surrounding waters turned into an icebox, said researchers on Friday at a symposium at the meeting of the American Association for the Advancement of Science in Boston.

The result was a virtually predator-free zone on the seafloor and a paradise for worms, sea lilies, clams, brittle stars and other bottom-dwelling animals.

All that is about to end, however. Global warming is now raising water temperatures to the point where, very soon, those long-exiled predators could return and wreak havoc on the ocean floor, say biologists.

"It's going to be a smorgasbord," said researcher Cheryl Wilga of the University of Rhode Island. She studies the metabolic limitations of sharks that have kept them from Antarctic waters for millions of years, but may not do so much longer.

"The species in the Antarctic (seafloor) have no defense for shell-crushing predators," said extreme species researcher Brad Seibel, also of the University of Rhode Island. "I don't think that anyone was really aware of this issue."

Along the Antarctic Peninsula, the northernmost, warmest part of the continent, global warming is raising air temperatures quickly. Water temperatures have been warming as well, at a rate of about 0.04 degrees Celsius per year, Wilga says. That comes to about one degree per 25 years.

Compared to the relative stability seen for tens of millions of years, that's incredibly fast. Already, crabs are showing up, and some sharks are poised to pounce once the thermal dinner bell rings.

Antarctic King Crab?

The first exiled predator to return to Antarctica is the king crab. The leggy crustaceans have been found way down on the deep slopes off the Antarctic continental shelf -- where the water is slightly warmer than elsewhere.

There they are fighting the cold, explained marine scientist Richard Aronson of Dauphin Island Sea Lab and the University of South Alabama.

The frigid water makes it hard for the crabs to efficiently flush magnesium out of their bodies, said Aronson. Too much magnesium acts like a narcotic on a crab.

"When it's too cold, the magnesium makes them pass out and die," Aronson said. That's probably why the crabs have been absent for eons. Now, however, in those slightly warmer depths off the continental shelf, it's just warm enough for the crabs to survive there.

As the upper waters continue to warm, nothing will stop the king crabs from moving up onto the continental shelf and feasting. That will "hammer" the old seafloor communities, Aronson said.

"We expect the populations (of seafloor invertebrates) to take a dive," said Aronson.

Giant Starfish, Lilly Fields Found in Antarctic Waters

2008-09-15T06:13:00.000-07:00

- Scientists who conducted the most comprehensive survey to date of New Zealand's Antarctic waters were surprised by the size of some specimens found, including jellyfish with 12-foot tentacles and 2-foot-wide starfish.

A 2,000-mile journey through the Ross Sea that ended Thursday has also potentially turned up several new species, including as many as eight new mollusks.

It's "exciting when you come across a new species," said Chris Jones, a fisheries scientist at the U.S. National Oceanic and Atmospheric Administration. "All the fish people go nuts about that -- but you have to take it with a grain of salt."

The finds must still be reviewed by experts to determine if they are in fact new, said Stu Hanchet, a fisheries scientist at New Zealand's National Institute of Water and Atmospheric Research.

But beyond the discovery of new species, scientists said the survey, the most comprehensive to date in the Ross Sea, turned up other surprises.

Hanchet singled out the discovery of "fields" of sea lilies that stretched for hundreds of yards across the ocean floor.

"Some of these big meadows of sea lilies I don't think anybody has seen before," Hanchet said.

Dolphin Rescues Stranded Whales

2008-09-15T06:09:00.000-07:00

Stranded? Try Me

- A dolphin guided two stranded whales to safety after human attempts to keep the animals off a New Zealand beach failed, a conservation official said Wednesday.

"I've never heard of anything like this before, it was amazing," Conservation Department officer Malcolm Smith said.

The actions of the dolphin, well known locally for playing with swimmers at Mahia beach on the east coast of the North Island, probably meant the difference between life and death for the whales, Smith said.

Smith had been working for over an hour and a half to save the two pygmy sperm whales which had repeatedly become stranded despite his attempts to push them back out to sea.

A bottlenose dolphin, named Moko by locals, appeared and guided the whales to safety after apparently communicating with them, Smith said.

The whales, a 10-foot female and her male calf, were apparently confused by a sandbar just off the beach and could not find their way back to open water.

Smith had been alerted at daybreak on Monday by a neighbor about the two stranded whales on Mahia beach near his home.

"Over the next hour and a half I pushed them back out to sea two or three times and they were very reluctant to move offshore," Smith said.

"I was starting to get cold and wet and they were becoming tired. I was reaching the stage where I was thinking it's about time to give up here, I've done as much as I can."

In that situation, whales are often humanely killed to end their suffering.

Smith said Moko arrived on the scene and he could hear the whales and the dolphin making noises, apparently to one another.

"The whales made contact with the dolphin and she basically escorted them about 200 yards parallel with the beach to the edge of the sandbar.

"Then she did a right-angle turn through quite a narrow channel and escorted them out to sea.

"There's been no sign of the whales since Monday, they haven't re-stranded."

"What the communication was I do not know, and I was not aware dolphins could communicate with pygmy sperm whales, but something happened that allowed Moko to guide those two whales to safety."

Moko has become famous for her antics at Mahia, which include playing in the surf with swimmers, approaching boats to be patted and pushing kayaks through the water with her snout.

Such close interaction with humans is rare among dolphins but not unknown. "She's become isolated from her pod obviously for one reason or another, but obviously made Mahia home just at the moment."

Mahia gets up to 30 whale strandings a year, most of which end with the whales having to be put down.

"I don't know if next time we have a whale stranding we can get her to come in again. She certainly saved the day for us and the whales this time."

North American Fish Under Threat

2008-09-15T06:07:00.000-07:00

Pacific Salmon | Video: Discovery Earth

- Nearly 40 percent of fish species in North America are imperiled, according to a new survey by fish experts, the U. S. Geological Survey, and the American Fisheries Society, up 92 percent from the last survey done in 1989.

North America hosts perhaps the greatest diversity of temperate freshwater organisms on Earth, including aquatic insects, mussels, crayfish and fish.

The new report, compiling assessments from fish experts in the United States, Canada and Mexico, found that of the 700 types of fish in the survey, 230 are "vulnerable," 190 are "threatened," 280 are "endangered," and 61 are believed extinct.

"A lot of effort has been expended since 1989, but things are still in a sorry state in many ways," said study author Eric Taylor of the University of British Columbia in Vancouver. "We can't be complacent with trying to address some of these declines."

No single cause explains the ongoing fish losses, Taylor and others agree. Habitat loss, invasive species, diseases, dams, and water contaminants all contribute.

"Fish are kind of canaries in the coal mine," said Howard Jelks of the USGS and lead author of the report, published in Fisheries. "If you change the water to something that's not able to support these fish, it's also not going to be as high quality for recreating, for eating the fish out of these streams, for drawing water that's ultimately used for drinking, or for other things."

Certain regions were identified as hotspots with both high fish diversity and high degrees of threat. These included the Pacific central valley, the western Great Basin, the Rio Grande, and several river systems in the southeast such as the Tennessee and Mobile.

Pacific Coast salmon and trout were among the most at-risk types of fish, as were minnows, suckers, and catfish across the continent. Almost half of the carp and minnow family and the family of fish including perch and darters were identified in one of the imperiled categories.

The new report lists distinct sub-populations of certain fish separately, even if they are classified as the same species, which accounts for part of the increase.

Fish to Be Trained to Jump Into Nets

2008-09-11T02:28:00.000-07:00

- Call them Pavlov's fish: Scientists are testing a plan to train fish to catch themselves by swimming into a net when they hear a tone that signals feeding time.

If it works, the system could eventually allow black sea bass to be released into the open ocean, where they would grow to market size, then swim into an underwater cage to be harvested when they hear the signal.

What's next, teaching them to coat themselves in batter and hop inside a fryer?

"It sounds crazy, but it's real," said Simon Miner, a research assistant at the Marine Biological Laboratory at Wood's Hole, which received a $270,000 grant for the project from the National Oceanic and Atmospheric Administration.

Miner said the specially trained fish could someday be used to bolster the depleted black sea bass stock. Farmed fish might become better acclimated to the wild if they can be called back for food every few days.

The bigger goal is to defray the costs of fish farming, an increasingly important source of the world's seafood. If fish can be trained to return to the farmer after feeding in the open ocean for several days, farms could save money on feed and reduce the amount of fish waste released in concentrated areas.

The key question for fish farmers: How many fish will actually return, and how many will be lost to predators or simply swim away?

Randy MacMillan, president of the National Aquaculture Association, said fish farmers won't be easily convinced to adopt open-ocean ranching.

"The commercial side is going to be skeptical," said MacMillan, who works on a trout farm in Idaho.

The Massachusetts project is one of several experiments funded by the federal government last year as part of aquaculture research.

"We're looking for innovations that will actually make a difference for coastal communities and the environment," said Michael Rubino, manager of NOAA Aquaculture. "It fits in both."

Previous experiments have used sound to train a fish to feed -- similar to what Russian scientist Ivan Pavlov did in his famous dogs that salivated at the sound of a bell, expecting food.

In Japan, scientists have used sound to keep newly released farmed fish in certain areas, where they could be caught in traditional ways.

But no one has ever tried to get fish to leave and return to an enclosure where they can be scooped up.

The project began last summer using 6,500 black sea bass, a stout, bottom-dwelling fish found between Florida and Cape Cod that migrates south of New Jersey in the winter. The species grows up to 3 pounds and 20 inches long and has a thick, white flesh that can be filleted for broiling or cut into nuggets for frying.

Miner said the first objective was to see if the fish could truly be trained. He got his answer after keeping the fish in a circular tank, then sounding a tone before he dropped food in an enclosed "feeding zone" within the tank that the fish could enter only through a small opening.

Researchers played the tone for 20 seconds, three times a day, for about two weeks. Afterward, whenever the tone sounded, "you have remote-control fish," Miner said.

"You hit that button, and they go into that area, and they wait patiently," he said.

Miner is now trying to figure out how long the fish remember to associate the tone with food. He feeds the fish outside the feeding zone without a tone for a few days and then tests if they will still head for the feeding area when the tone sounds again.

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Sea Cucumber Inspires Nano-Material

2008-09-11T02:27:00.000-07:00

One Bendy Critter

Scientists have created a breakthrough substance that can change in seconds when exposed to liquid, shifting from hard plastic to soft and back again, and that has a wide range of potential medical applications.

The material -- inspired by the skin of sea cucumbers -- has astounding "mechanical morphing characteristics," according to an article published in the latest issue of Science.

Researchers said a plethora of possible biomedical applications exist for the malleable new material, including as part of "artificial nervous systems" for patients with Parkinson's disease, stroke or spinal cord injuries.

Sea cucumbers, found on ocean floors around the world, have leathery skin, an elongated, cucumber-like shape, and a consistency that can be either gelatinous, stiff and rigid, or anything in between.

This "switching effect" in the tissue of the sea cucumber is derived from a distinct nanocomposite structure in which highly rigid collagen nanofibers are embedded in a soft connective tissue.

Now the school of engineering at Case Western Reserve University and researchers at the Louis Stokes Cleveland Department of Veterans Affairs Medical Center have succeeded after years of effort in mimicking the unusual architectural structure of the sea creatures.

Colossal Squid Dissection Reveals Toothfish Diet

2008-09-11T02:26:00.000-07:00

Big, Hungry Squid

- Scientists examining the world's largest known colossal squid this week could find nothing in the cephalopod's stomach, suggesting the large marine animal was starving when it was captured in February of 2007.

That might help to explain why the squid was caught in the first place. The huge, jelly-like animal from Antarctica was voraciously eating an Antarctic toothfish hooked in a New Zealand long-line fishing operation in the Ross Sea when fishermen hauled up their catch, revealing the then half-dead, enormous squid.

View a slideshow of the colossal squid here.

The fishermen netted the squid and placed it in their vessel's freezer. It remained frozen until last week, when scientists at The Museum of New Zealand Te Papa thawed and analyzed the squid. Part of that investigation involved the insertion of an endoscope into the specimen's stomach.

"The endoscope revealed nothing," museum spokesperson Jane Keig told Discovery News. "Its stomach was empty."

Last week, the squid project's director, Carol Diebel, told Discovery News there were plans to remove tissue samples from the squid's stomach, but the researchers instead decided not to cut into the colossal squid, as "any kind of dissection could harm it" before the squid goes on public display in a specially constructed fluid-filled tank.

The Colossal Squid's Favorite Food

Diebel and her team instead focused their dissection efforts on yet another colossal squid housed in the museum. This second squid was laid out on a trough-like table next to the primary specimen for much of the week.

The stomach of that second squid yielded the remains of toothfish. Prior studies of colossal squid remains found in the stomachs of whales also revealed evidence of toothfish consumption, so scientists believe this fish could comprise a large portion of the colossal squid's diet.

The word "toothfish" generally refers to two closely related species: the Patagonian toothfish, popularly known as Chilean sea bass, and Antarctic cod, which is sometimes referred to as Antarctic toothfish. Both species possess a rather toothy, gaped mouth, hence the name, and can grow to around 7 feet or more in length.

Recently it was determined that the Antarctic toothfish possesses special proteins in its body that act like anti-freeze, preventing its blood from freezing into a solid block in the ice-laden, high latitude waters where it lives. Both the toothfish and the colossal squid favor deep water, 3,000 or more feet below the surface, and each has developed special adaptations to live and hunt in the darkness of that environment.

Hunting in the Dark

During this week's colossal squid investigation, the researchers were able to get an up-close look at the squid's tentacles. The tentacle tips -- appropriately called "clubs" -- are armed with two rows of sharp hooks that can swivel in all directions.

While no one has closely observed a colossal squid in hunting action, it's believed the animal moves quickly, grabbing toothfish and other prey with these spiked tentacles, which ironically somewhat resemble long-line fishing lines.

The scientists also discovered the squid has basketball-sized eyes, "the largest known in the animal kingdom," according to Diebel, along with a light organ right near the eye sockets. She believes this organ may function like a searchlight.

Toothfish also possess special eyes, with retinas that are well adapted to low light levels. While the mostly clear squid is nearly invisible in deep water, it's probable that colossal squid and toothfish play a continual hide and seek game of survival, where who spots whom first determines which one could live another day.

The Big Beak's Bite

The defrosted colossal squid's beak suggests the animal was much larger than it is now, a fact that's been supported by the men who witnessed the squid before it went into the freezer. Due to water and temperature changes, the squid shrunk to around 14 feet in length. Despite such alteration of the squid's flesh, its beak remains fully intact.

Among the colossal squid's many mysteries has been: How can an animal the consistency of firm Jell-O bite into prey without tearing itself to pieces?

Australia Shark Count Breaking Records

2008-09-11T02:24:00.000-07:00

Topping the List

- Australians apparently have a good chance of spotting a shark in the wild, since a new project called the Great Australia Shark Count has thus far determined at least 4,022 sharks swim in waters surrounding the land down under.

While that figure is expected to rise as the count continues, the project has already broken records and is now considered to be the world's largest community shark count, Michael Rupnik, the project's executive officer, told Discovery News.

Prior contenders for that title were the award-winning Ecocean whale shark project, which has reported 1,100 shark sightings in over 10 years, and the global Shark Trust, which has had about 200 shark sightings since 1997.

Adam Smith, national chair of the Australian Underwater Federation that is overseeing the count, credits its success to two reasons.

"Firstly, we have lots of sharks in Australia and people love getting in the water and diving and fishing," he said, adding that Australians also possess "a thirst for knowledge and want to make a difference."

Count participants include scuba divers, underwater spear fishermen and many other recreational water users.

While the project will continue throughout the year, the current most reported shark is the wobbegong, with 903 sightings. The grey nurse shark follows, with 733, and Port Jackson sharks round out the top three with a count of 519.

Other commonly spotted sharks include the grey reef shark, the whitetip reef shark, whale sharks, the blacktip reef shark, the tiger shark, gill sharks and the toothy great white. So far, participants have recorded 13 great white sightings.

U.S. Shark Bill Targets Finning Loopholes

2008-09-11T02:22:00.000-07:00

Maximum Profit

After the U.S. House of Representatives subcommittee hearings last month, a new shark bill promising to close disturbing loopholes in existing shark fishing regulations has inched a step closer to becoming law.

The bill, entitled The Shark Conservation Act of 2008, specifically addresses the problem of finning, or removal of a shark's fins for shark fin soup, folk remedies and other forms of consumption.

Because of this practice, shark fins are among the world's most valuable fishing products, but the real price is that sharks are further threatened with extinction, since the marine predators usually die once their finless bodies are tossed overboard.

Sharks are also a slow-growing fish, with some species producing few pups, so recovery from over-fishing is next to impossible.

"The Shark Conservation Act of 2008 reestablishes the intended protections for sharks under U.S. law," said Congresswoman Madeleine Bordallo (D-Guam), who is Chairwoman of the Subcommittee on Fisheries, Wildlife and Oceans.

"I look forward to working with my colleagues on both sides of the aisle to advance this timely and important bill," she added.

Existing Loopholes

Bordallo explained that the bill attempts to close at least three loopholes. The first addresses the difficulty of enforcing "fin to carcass" ratios aboard vessels. Under current regulations, many fishermen can collect fins, so long as a comparable weight of shark bodies accompanies them.

"It has proven virtually impossible, however, to determine whether a given set of fins belong to a particular dressed carcass," she said. "As a result, there are reports of fishermen mixing fins and carcasses for maximum profit, continuing to discard less desirable, finned sharks at sea."

Humpback Whales Make Huge Comeback

2008-09-11T02:20:00.000-07:00

Once hunted to the brink of extinction, humpback whales have made a dramatic comeback in the North Pacific Ocean over the past four decades, a new study says.

The study released Thursday by SPLASH, an international organization of more than 400 whale watchers, estimates there were between 18,000 and 20,000 of the majestic mammals in the North Pacific in 2004-2006.

Their population had dwindled to less than 1,500 before hunting of humpbacks was banned worldwide in 1966.

"It's not a complete success, but it's definitely very encouraging in terms of the recovery of the species," said Jeff Walters, co-manager of the Hawaiian Islands Humpback Whale National Marine Sanctuary.

The study, sponsored by the National Oceanic and Atmospheric Administration, is the most comprehensive analysis ever of any large whale population, said David Mattila, science coordinator for the sanctuary.

At least half of the humpback whales migrate between Alaska and Hawaii, and that population is the healthiest, Mattila said.

But isolated populations that migrate from Japan and the Philippines to Russia are taking a longer to recover after whaling operations ceased, he said.

"Whales are long-lived and give birth one at a time .... so if the population gets pushed too low, it may take quite awhile to come back. Maybe that's what's happening in the west," Mattila said.

The whales are protected under federal laws that include the Marine Mammal Protection Act and the Endangered Species Act.

Colossal Squid's Size Key to Survival

2008-09-07T03:50:00.000-07:00

Big, For Good Reason

- The frozen colossal squid that was thawed this week shrank drastically due to water and temperature changes since it was accidentally caught by fisherman in 2007, according to officials at The Museum of New Zealand Te Papa who revealed the exact size of the squid on Thursday and believe it is still the world's largest known squid.

View a slideshow of the colossal squid here.

After waiting for the tentacles to defrost so the squid could be fully extended, the researchers measured its weight at 1,091 pounds and its length at nearly 14 feet.

The squid's heft and large beak "confirm that it was almost certainly longer and is still the largest invertebrate specimen in the world," Te Papa spokesperson Jane Keig told Discovery News.

She added that it also has the largest eye of any animal at about 10.5 inches in diameter.

Other Ocean Giants

Colossal squids exemplify a phenomenon known as deep-sea gigantism, which is the tendency for invertebrates, crustaceans and other creatures of the deep to grow to become much larger than their shallower water counterparts. Some squid, in contrast to the colossal, are just a few inches long.

Dutch biologist Olaf Blaauw, who traveled to New Zealand to analyze the enormous squid, told Discovery News that whales serve as other obvious examples of gigantism. Sharks may grow to extreme lengths too.

"A whale shark can attain a length in excess of 45 feet," he said. "Basking sharks get over 30 feet…There are probably deep water shark species yet undiscovered, based on anecdotal evidence and further strengthened by the discovery of the 15-feet megamouth shark relatively recently."

He added that ocean sunfish also grow to be very large at 10 feet long and high, and weighing up to 2 tons -- "probably the heaviest bony fish around."

Another possible member of the colossal group is the giant leatherback sea turtle, which can grow to around 8 feet in length and weigh close to a ton. Japanese spider crabs and oarfish (a type of herring) also exhibit gigantism, along with other types of squid and octopi.

Why So Big?

From a Darwinian fitness perspective, "if any attribute favors survival, it will be preserved in a species until circumstances change to make another random change in shape, form or behavior more favorable," Blaauw said.

The size of these deep-sea monsters therefore somehow improves their longevity and rate of survival.

One obvious reason is that a big body can be intimidating to other animals.

"Suffice it to say, there is little out there that can tackle a thousand-pound squid armed to the beak with powerful arms, each lined with vicious hooks and suckers," Blaauw said.

Aside from humans, the colossal squid's only other natural enemies are the occasional large shark and sperm whales, which seem to have a real taste for the cephalopod giants because they hunt them voraciously. Researchers aren't even certain that a shark can actually kill a colossal squid. Large squid remains have been found in shark stomachs, but it's possible the sharks just scavenged their already dead remains.

Size Affects Eating

Whether on land or in the ocean, an animal's size appears to predict how and what it eats. Scientists first began to make this correlation after they noticed that particularly large creatures are more vulnerable to habitat changes than smaller animals are.

John Haskell of Utah State University and his colleagues developed a computer model to explain why that's the case. They discovered the way an animal forages can be directly linked to its length and weight.

"What we found is that an organism's body size is a key determinant of how often it can be expected to encounter food in its environment," Haskell said. "Resource density is often scale-dependent, that is it changes with the scale of measurement. The food density you see at one square meter changes when you zoom out to one square kilometer."

In essence, a tiny squid looks at the world a few inches at a time, while a colossal squid must look at potentially miles at a time, perhaps somewhat explaining its gigantic eyes. Prey appears to be more sparse and patchy for larger animals, which need to cover expansive territories to get their fill.

If predictions made by Haskell's model hold up, the more the colossal squid's habitat becomes fragmented, the larger its home range will become, potentially causing the squid to grow even larger and to travel longer and longer distances for food.

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Shark Attack Kills San Diego Man

2008-09-07T03:47:00.000-07:00

After the Attack

- A shark on Friday attacked and killed a 66-year-old swimmer who was training in the ocean off San Diego County with a group of triathletes, authorities said.

The man was attacked by what authorities believe was a great white shark at Tide Beach around 7 a.m., authorities said.

The man, a local resident whose identity was not immediately released, was taken to a lifeguard station for emergency treatment but was pronounced dead at the scene, according to a statement on the Solana Beach city Web site.

The man's injuries crossed both thighs and were made "by what is probably a great white shark," San Diego County sheriff's Sgt. Randy Webb said in a statement.

"It looks like the shark came up, bit him, and swam away," said Solana Beach Deputy Fire Chief Dismas Abelman.

The attack took place about 150 yards offshore. Several swimmers wearing wetsuits were in a group when the shark attacked, said Solana Beach lifeguard Craig Miller. Two swimmers were about 20 yards ahead of the man when they heard him scream for help. They turned around and dragged him back to shore.

Swimmers were ordered out of the water for a 17-mile stretch around the attack site and county authorities sent up helicopters to scan the waters for the shark.

"The shark is still in the area. We're sure of that," Mayor Joe Kellejian said.

Rob Hill, a member of the Triathlon Club of San Diego, said he was running on the beach while about nine other members were in the water when the attack took place.

Shark Oil Contaminated by VCR Chemical

2008-09-07T03:46:00.000-07:00

Hazardous to Your Health?

- A flame retardant found in everything from consumer electronics to furniture is contaminating waters where sharks swim and winding up in fish oils sold as nutritional supplements, according to a new study published in the journal Food Chemistry.

Scientists led by Kensaku Kakimoto of the Osaka Prefectural Institute of Public Health in Japan analyzed fish oils purchased from Japanese markets for the presence of the potentially toxic chemical hexabromocyclododecane (HBCD).

The researchers first chemically separated the oils into their basic ingredients, and then used mass spectrometry, a process that looks at charged particles, to identify the presence of HBCD.

They found it in 15 of the 22 samples. While concentrations varied, some sardine and shark liver oils from fish captured near Japan contained "relatively high levels of HBCD, indicating that both the surface and deep seawaters around Japan may have been contaminated," the researchers wrote.

It's unknown how the chemical wound up in the water, but an event as simple as someone dumping a VCR into a landfill could contribute to the problem, since rainwater could wash the chemical into oceans or the chemical could vaporize and enter the atmosphere, according to Tim Fitzgerald, an Environmental Defense Fund marine scientist.

Shark liver oil manufacturers don't always state what species the oil came from, but it is commonly derived from deep-sea sharks, dogfish sharks and basking sharks. As the name suggests, the oil is extracted from the livers, which can make up about 25 percent of the shark's total body weight.

Although certain chemicals in shark liver oil have been studied as immune system stimulants, there is little medical evidence to support some of the oil's purported health benefits, which range from treating radiation sickness to pimple breakouts to cancer.

Trapped Sea Lions Shot Dead

2008-09-07T03:45:00.000-07:00

Sitting Ducks

- For years, the sea lions lounging at the Bonneville Dam have had easy pickings from salmon waiting to go up fish ladders to upriver spawning grounds.

Over the weekend, the federally protected sea creatures were themselves easy prey for a gunman who shot and killed six of the sea lions as they lay in traps meant to humanely catch them.

State and federal authorities were investigating the shootings, which came less than two weeks after an appeals court issued a temporary injunction against authorities killing the salmon-gobbling mammals. Agents have been trapping them instead, but trapping will be suspended during the investigation, said Rick Hargrave, a spokesman for the Oregon Department of Fish and Wildlife.

Fishermen and American Indian tribes have pushed to protect the salmon and remove the sea lions, by lethal force if necessary.

The carcasses of the four California sea lions and two Steller sea lions were found Sunday around noon below the Bonneville Dam on the Columbia River on the border of Oregon and Washington.

The six animals appear to have been shot by somebody on the Washington side during the night, said Brian Gorman, a spokesman for the National Marine Fisheries Service.

Two open cages each contained the carcasses of two California sea lions and one Steller sea lion, he said.

Sharks Ruled Alabama's Dino-Era Waters

2008-09-07T03:36:00.000-07:00

Goblin Shark Descendent

- The American South's golden age for sharks might very well have been the Cretaceous Era during the dinosaur age, according to tooth remains found for a number of different species.

Most recently, the teeth of Scapanorhynchus texanus, also known as the "goblin shark of Texas," were found and dated to between 78.8 and 79.2 million years ago

The teeth were recovered from what is now a vertical cliff next to a creek in western Alabama. The spot was once a seabed below waters teaming with unusual looking fish, including the now-extinct shark.

"Judging from the abundance of shark teeth preserved in the Cretaceous of Alabama, sharks were abundant in Alabama seas during the Cretaceous," Martin Becker, who led the project, told Discovery News.

"Shark teeth are also abundant, however, in Cretaceous deposits of the Gulf Coast and the Atlantic coastal plain, so it's pretty clear that they were abundant up and down the coast of what is now the United States," added Becker, an associate professor of environmental science at William Paterson University.

Becker and colleagues David Seidemann, John Chamberlain, Dieter Buhl and William Slattery studied 15 fossil shark teeth from the vertical cliff created by Trussels Creek in Greene County, Ala. Although the researchers focused on the goblin shark specimen, also nicknamed "spade snout," they believe some of the teeth belonged to different sharks because the deposit concentrated materials coming from various parts of a seabed.

They cut slices of the teeth to study its three different types of tissues: the orthodentine and osteodentine, which form the pulp cavity and root structure of a tooth, and the enameloid, which is the hard outer surface.

The scientists then determined the strontium isotope composition of each of the different types of tooth tissue. Strontium isotopes have a radioactive component that increases incrementally over time as the result of decay. When compared with the non-changing part of the metal's atoms, scientists can date tooth fossils.

They can also reconstruct past environments, since the chemical composition of the teeth usually locks in certain isotopic signatures of the seawater in which the shark lived.

The findings have been accepted for publication in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

The researchers discovered that tooth enamel provided far more accurate data than the other parts of the tooth, suggesting that future studies should focus only on the hard enamel surfaces.

"We expect that enamel in any creature would be less susceptible to alteration after its formation than the other dental tissues, probably because enamel is well-crystallized and not as porous as dentine," explained Seidemann, a Brooklyn College geochemist.

Shark Fin Demand Pushes 11 Species Near Extinction

2008-09-04T04:28:00.001-07:00

Heavy Price

Overfishing driven in part by an insatiable appetite for shark-fin soup has threatened 11 species of the ocean-dwelling predators with extinction, according to a report released on Thursday.

The first study to assess the worldwide status of 21 species of pelagic sharks and rays -- those living and hunting in open seas -- found that more than half are rapidly being fished out of existence.

Particularly vulnerable species include the short-finned mako, the thresher and the silky, said the report, to be published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems.

"Despite mounting evidence of decline and increasing threats to these species, there are no international catch limits for oceanic sharks," said co-author Sonja Fordham, a researcher at the Oceans Conservancy and Shark Alliance in Brussels.

"Our research shows that action is urgently needed on a global level if these fisheries are to be sustainable."

Many big shark species have fallen prey to booming Asian economies where shark-fin soup is prized as a must-have delicacy at weddings and other banquet occasions. The fins are often sliced off of living fish which are then discarded in the sea.

Accidental "by-catch" by industrial fishing operations have also decimated shark populations, the study said.

Sharks and big rays are especially vulnerable to overfishing because they take many years to reach sexual maturity and have relatively few offspring.

"We are losing species at a rate 10 to 100 times greater than historic rates," said the study's lead author, Nicholas Dulvy, a professor at Sime Fraser University in Vancouver, Canada.

The report, presented at a major UN conference on biodiversity in Bonn, calls for the establishment and enforcement of science-based catch limits for sharks and rays, and a ban on the practice of "shark finning."

The 11-day Bonn conference seeks to prevent the destruction of countless plant and animal species.

It is the ninth of its kind of countries who signed up to the UN Convention on Biological Diversity at the 1992 Rio Earth Summit.

Oldest Live Birth Captured in Fish Fossil

2008-09-04T04:27:00.000-07:00

"Mother Fish"

- She is the oldest mother of any species ever found, a 380-million-year-old fish immortalized in a fossil while still attached to her offspring by an umbilical cord.

Dubbed "mother fish" by the scientists who discovered her in northwestern Australia, Materpiscis attenboroughi is not only an entirely new genus and species, but pushes back the first known case of live birth in the animal kingdom by some 200 million years.

The tail-first birthing process was probably similar to that of some species of sharks and rays living today, says the study, published Thursday in the British journal Nature.

"The discovery is certainly one of the most extraordinary fossil finds ever made, and changes our understanding of the evolution of vertebrates," commented lead researcher John Long, head of science at Museum Victoria.

Long and his colleagues were particularly astounded to find such a sophisticated reproductive system so far back on the evolutionary clock.

"It shows us that live birth was occurring at the same time as egg laying, and that these mechanisms evolved together rather than sequentially," explained co-author Kate Trinajstic, who together with Long found the fossil.

The existence of the embryo and umbilical cord within the specimen also provides the first-ever example of "internal fertilization" -- that is, sex with penetration, the study says.

About 10 inches long, "mother fish" belongs to an extinct group of vertebrates, known as placoderms, that thrived during Middle Palaeozoic Era some 420 to 350 million years ago.

Antarctic Mega-Iceberg Suffocates Seals

2008-09-04T04:26:00.000-07:00

Life Before the Berg

Weeks after the controversial listing of polar bears as threatened species, new research graphically demonstrates how changes to polar ice can devastate local animals.

The findings of a grim new study illustrate the direct, and often immediate, effects that climate change can have on the physiology, behavior and survival of wild species.

An Iceberg the Size of Rhode Island

In 1998, ecologist and evolutionary biologist Terrie Williams of the University of California at Santa Cruz and her team began a study on Weddell seals in Antarctica.

Three years later, an enormous iceberg detached near Antarctica's McMurdo Sound. According to Williams and her colleagues, the event was caused by global warming, which has likely been melting and weakening ice at the poles.

The 4,200-square-mile iceberg -- dubbed B-15 -- drifted westward and lodged on nearby Ross Island. The lives of countless animals would soon forever change.

Seals Struggle for Breathing Room

"Our first clue that there was a problem was that the seals were not returning to their usual pupping areas, and that there were fewer seals even later in the season," Williams told Discovery News.

She and her colleagues noticed that the ice around Ross Island did not experience its usual "break-out" that year. Normally the ice thaws, creating thinner areas where diving seals can carve breathing holes in the ice shelf. Instead, the presence of B-15 thickened the surrounding ice.

"We started out with three feet of ice and were up to a nine feet thickness" by 2002, the last year of the study, Williams said.

Filming both above and below the thickened ice, Williams and her colleagues observed seals lining up to breathe at the few holes they were able to make with their front canine teeth. Lacking the energy to swim further, fights ensued in the lines, with animals lashing out at each other for access to air.

Williams explained that after B-15 dislodged, there were 80 miles of ice between McMurdo and the open ocean.

"Weddell seals can only swim four miles under ice before they have to come up to breathe, so you can see the problem," she said.

Physiological Systems Overtaxed

The researchers measured the oxygen consumption of seals that managed to surface, and by analyzing the underwater video, calculated the energy cost of each stroke the seals made during dives.

After comparing these calculations with prior data on seals diving under normal conditions, the researchers found that the new environment simultaneously increased the seals' need for oxygen and reduced their access to air.

Since seals dive to hunt, most were unable to catch enough prey to sustain themselves and their pups.

Fishing Nets Entangling Fewer Dolphins

2008-09-04T04:24:00.000-07:00

The most recent dolphin counts in the eastern tropical Pacific Ocean suggest that two species decimated by deaths in tuna fishing nets may be making a comeback.

Populations of the northeastern offshore spotted dolphin and the eastern spinner dolphin plummeted by 80 and 70 percent, respectively, between 1960 and 1990, as they were caught in nets set for tuna. More than six million dolphins have died this way since the late 1950s.

Thanks to increasingly strong regulations to prevent these deaths passed in the 70s, 80s and 90s, dolphin deaths have declined drastically, with fewer than 1,000 dolphins now dying a year in nets.

"Because they were so good at reducing the mortality, we've been expecting the population to recover for quite some time now," said Jeremy Rusin, of the National Oceanic and Atmospheric Association's Southwest Fisheries Science Center in La Jolla, Calif.

It took longer than expected to see improvement, but the latest survey, conducted in 2006, estimates the northeastern offshore spotted dolphin population at 857,884, up from 822,157 in 2003, and 636,780 in 2000. NOAA estimated the eastern spinner dolphin population at more than 1.06 million in 2006, compared with 673,943 in 2003.

Although the counts show an increase, Rusin emphasized that the results do not indicate a conclusive trend. The large area covered by the survey -- almost the size of North America -- means the estimates carry large uncertainty.

"We need additional surveys to be sure that the increases we've seen this year are real increases, and not just the reflection of statistical uncertainty," Rusin said.

One group of dolphins, the western/southern spotted dolphins, continued to decline. This finding, coupled with the rise of the northeastern offshore spotted dolphin, may simply be explained by a migration of some individuals from one zone to another, Rusin said.

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Fish 'Fly' Against Currents With Wing-Like Fins

2008-09-04T04:19:00.000-07:00

Flying Parrotfish

- A team of researchers has found how some reef fish use their fins to fly underwater, allowing them to survive in the sometimes cyclonic currents surrounding coral reefs.

The research, led by Chris Fulton from The Australian National University, appears in the journal Coral Reef.

Fulton says he first noticed the wing-like fins during surveys of coral reefs in Australia.

"We were surveying different reef fish across different gradients on the Great Barrier Reef and we noticed that some of the ones that lived in the very shallow areas were very abundant -- lots of individuals of just a few species," Fulton said.

"When we looked at those few species in a bit more detail, we noticed something a bit unique about their fins -- a wing-shaped fin."

The wing shape allows fish such as parrotfish, wrasse and surgeonfish to fly through the water using a figure-of-eight pattern.

"Most fish when they move their pectoral fins on the side of their body, they move them just like you row a boat -- they have a power stroke and then a recovery stroke," Fulton says. "By doing that they are only creating thrust half the time."

He says fish with wing-shaped fins keep them spread at all times and sweep in a figure-of-eight pattern that constantly generates thrust.

"They do this by inclining their fins at just the right angle to create lift from the water flowing over the fin, similar to the way air moves over the wing of a bird to propel them through their air," Fulton said.

Fulton believes the extra push that the wing-like fins give the fish helps them survive in the shallow and sometimes turbulent waters surrounding coral reefs.

"They're dealing with waves crashing on to them all day, everyday, and those crashing waves create water motions that are extreme," he said.

"If you scaled up the differences in the thickness of water to the thickness of air ... it would be like us dealing with cyclone force winds everyday."

Chris and his colleagues, David Bellwood from James Cook University and Peter Wainwright from the University of California, Davis, observed the fish swimming around the reef and in flow tanks, which allowed them to record the fish's movement on high-speed video cameras.

"We set up a high-speed video, which records about 200 frames per second and we run them at different speeds in the tank and record the motion of their fins on the high-speed camera," he said.

They found some species could move at up to 10 body lengths per second. By comparison, Olympic champions reach speeds of just 1.3 body lengths per second, and then only for the brief 22 seconds of the 50-meter freestyle sprint.

Fulton says the U.S. Office of Naval Research has taken interest in the research, looking to use it in the development of future remote control submersibles.

"Things that we are learning from 50 million years of evolution have taught us that fish are a very good solution," he said.

But Fulton doesn't envisage Olympic swimmers using the winged-shaped technique in the near future.

"It may give us ideas for a new swimming stroke in a human, how to make fine adjustments in the swimming stroke at different speeds," he said. "But humans are constrained by our rather clumsy sort of limbs that aren't really made for water."

Bug-Eyed Flatfish Evolution Revealed

2008-09-02T00:25:00.000-07:00

Left-Eyed Flatfish

- Starting with Charles Darwin, evolutionary biologists have fretted and fought over the origins of flatfish, among the handful of weird, deeply asymmetrical creatures in Nature's bestiary.

Did flatfish wind up with two eyes on the same side of a lopsided skull through a few chance mutations?

Or did this happen gradually, over tens of millions of years?

The answer, in turns out, has been gathering dust for nearly two centuries in museum drawers, according to a study published Thursday in the British journal Nature.

That was where Matt Friedman, a graduate student at the University of Chicago, found two fossils that clearly show a glacial evolutionary shift from normal upright fish to their bug-eyed, bottom-hugging descendents.

Each dates from the Eocene epoch, some 45 million years ago, and one -- Heteronectus chaneti -- is an entirely new genus and species.

The other is from the Amphistium genus, whose earliest known specimens date back some 200 million years.

Both are true "missing links," with one eye just below the dorsal fin on the side of the fish closest to the ocean floor.

For reasons unknown to scientists, some species of modern flatfish, such as turbot, have both eyes on the left side, while other -- halibut and sole, for example -- see from the right side.

The two fossils "deliver the first clear picture of flatfish origins, a hotly contested issue in debates on the mode and tempo of evolution," said Friedman.

There can no longer be any doubt, he said in a statement: "The evolution of the profound cranial asymmetry of extant flatfishes was gradual in nature."

The flatfish controversy has vexed scientists for at least 150 years, and even provided fodder for creationist challenges to the very notion of Darwinian evolution.

All the great figures of early evolutionary biology weighed in with theories falling roughly into two schools.

The absence of any fossils showing a halfway point between normal fish and flatfish led some to believe that change took place in dramatic leaps, a process they called "saltation".

Others, including Darwin himself, predicted that we would one day find evidence of a gradual eye migration that mirrors the maturation of living forms.

When flatfish are only days old they are perfectly symmetrical.

But they rapidly metamorphose as they grow, with one eye migrating toward the other.

Neither of the key fossils rediscovered by Friedman had been examined with modern scientific tools for fear of causing damage.

But Friedman was finally allowed to treat a single specimen housed in the Naturhistorisches Museum in Vienna with a weak acid bath, and to carry out computer-based tomography imaging of the skull of another specimens at the Natural History Museum in London.

Both fossils had been found in limestone quarries in northern Italy.

Singing for Sex: Even Toadfish Do It

2008-09-02T00:20:00.000-07:00

Everything But the Girl

- It's not exactly Tony serenading Maria in "West Side Story," but for all their homeliness toadfish also sing to attract mates.

OK, singing may be a stretch; it's more of a hum. But it turns out to be useful, for science as well as the fish. Exploring how their nervous system produces sounds is allowing scientists to trace the earliest developments of vocalization in other animals, including people.

Many animals communicate vocally -- birds chirp, frogs thrum, whales whistle -- and comparing the nerve networks in a variety of vertebrates suggests that making sounds originated in ancient fishes, researchers report in Friday's edition of the journal Science.

The sounds of whales and dolphins are well known, but most people don't realize fish also make sounds, lead researcher Andrew H. Bass of Cornell University said in a telephone interview. He's a professor of neurobiology and behavior.

"I'm not saying fish have a language or are using higher powers of the brain," he added quickly. "But some of the networks of neurons, nerve cells in the brain, are very ancient."

The whole nervous system basis that led to speech originated in fish hundreds of millions of years ago, he said.

He studied the hindbrain in the larvae of midshipmanfish and toadfish, which grow up to produce more than one type of sound.

"It's not as complex as what you hear mammals and birds doing; it's the simplest type of communication ... but the parts of the nervous system that generate sounds are easiest to study in these fish," Bass said.

His team found two major uses of sound.

One is the hum in which the male sings to attract the female to his nest. Bass characterized it as like the drone of bees or a motor running.

The second type is a threat sound, more of a grunt or growl, to protect nesting territory.

The locations of the vocal nerves described in the study are consistent with the organization of the vocal systems in frogs, birds and mammals, supporting the idea of a common early development, Daniel Margoliash and Melina E. Hale of the University of Chicago comment in a perspective on Bass's study.

However, they add: "The story of the evolution of vocalizations is still being written, both for its deep ancestral roots and for its most modern development."

The research was funded by the National Science Foundation and the National Institutes of Health.

Coral Reef 'Glue' May Not Stick Under Climate Change

2008-09-02T00:19:00.000-07:00

Losing Their Stick

- The cement that buttresses coral reefs, giving them the strength to withstand crashing waves and other onslaughts, may stop forming as oceans acidify under increased carbon dioxide in the atmosphere.

Researchers have already predicted that a more acidic ocean will make it more difficult for corals to build their calcium carbonate skeletons. The new finding suggests that the reef's broader structure may also suffer because a lower pH reduces the formation of the reef's cement binder. The binder is made from calcium carbonate that precipitates out of ocean water when it rushes through the pores of coral skeletons.

"Until now, we've mostly addressed acidification in terms of what it does to the living organism," said study author Joan Kleypas of the National Center for Atmospheric Research in Boulder, Colo.

"Here we're finding that the reef structure itself can certainly feel the effect of ocean acidification, even if the biology somehow finds a way to cope with acidification. This is mainly an inorganic process, so we're looking at something that will happen regardless of what the biology does."

The researchers made their findings by comparing places around the world where CO2 levels in the ocean vary naturally.

The eastern tropical Pacific Ocean, near the Galapagos Islands, has particularly high CO2 concentrations because it is an upwelling spot where deeper waters, enriched in CO2 by microbial degradation of organic matter down below, rise to the surface.

"The eastern Pacific is in essence a natural laboratory to study how coral reef ecosystems are structured and function under these acidic conditions," said study author Derek Manzello of the University of Miami.

The researchers made measurements of the seawater and the amount of coral cement present in reefs near the Galapagos, and compared those with levels found near the Pacific coast of Panamá, and with those in the Bahamas.

Reefs in the Galapagos had the highest levels of carbon dioxide, which corresponded to water less saturated with carbonate ions -- and only trace amounts of cement on the reefs.

Shark Avoids Suffocation by Turning Off Electricity

2008-09-02T00:18:00.000-07:00

Capable of Extreme Survival

Lack of oxygen can do in most creatures, but a new study has found epaulette sharks have evolved a clever solution for avoiding suffocation -- they shut down their body's electrical activity and even go temporarily blind until they can properly "breathe" oxygen again through their gills.

The discovery puts the shark on the short list of vertebrates that can tolerate situations where there is zero to very little available oxygen. In addition to the shark, these include the crucian carp, freshwater turtles and leopard frogs.

For the shark, breathing can become a challenge when the sun goes down.

"The epaulette shark lives on shallow parts of the Great Barrier Reef where hypoxia (low oxygen levels) is common at night, particularly during low tide when their habitat may become cut off from the ocean," explained Goran Nilsson, who worked on the study.

Nilsson, a professor in the Department of Molecular Biosciences at the University of Oslo, and his colleagues made the determination through use of a non-invasive technique for studying one indicator of shark-produced electricity: eye electrical activity.

The researchers first anesthetized the sharks, captured by hand at Australia's Great Barrier Reef, and acclimated them to a seawater tank at the nearby Heron Island Research Station. The scientists lowered the oxygen levels in the tank and lightly touched an electrode to the shark's eyes while shining a light into them. The measured response of various energy waves emitted by the eyes revealed the shark's electricity output in terms of vision.

The scientists found that the epaulette shark completely shuts down the response of nerve cells in the retina, or the light-sensitive membrane that lines the inner eyeball. These cells normally transfer information to the visual nerve so, when outside oxygen levels are low, the shark essentially goes blind.

Since the eyes represent just one aspect of shark electricity production, it's believed that the spotted fish probably shuts down other parts of its central nervous system. Electrical activity accounts for 50 percent or more of nerve energy consumption, so reducing it allows the shark to tolerate low oxygen conditions.

Humans, in contrast, may pass out if they have trouble breathing, but this is often a severe shut down that could lead to even more problems. The epaulette shark fully recovers from its downtime state.

The researchers, whose paper has been accepted for publication in the journal Comparative Biochemistry and Physiology, Part A, conducted the same eye test on freshwater turtles and leopard frogs. The turtles actually beat out both the sharks and the frogs in their ability to tolerate zero to low oxygen.

The turtles didn't lose their eyesight and hardly changed at all, despite some reduced brain activity. Prior studies show crucian carp also have an incredible tolerance for conditions that would suffocate nearly all other animals.

Nilsson explained that these species evolved the David Blaine-like seemingly magical ability in order "to allow overwintering at the bottom of ice-covered ponds, small lakes and streams."

He added, "This habitat can become free of oxygen for several months during the winter."

Les Buck, associate professor in the Department of Cell & Systems Biology at the University of Toronto, told Discovery News that the new study "is interesting" particularly because it demonstrates that "visual information can be sacrificed in the severely hypoxic situation."

Since the epaulette shark has evolved its low oxygen tolerance at a temperature close to that of the human body, Nilsson said studies on the shark "could give us additional information on strategies that animals have evolved" to cope with natural happenings akin to what occurs when a person suffers a stroke, a heart attack or certain complications related to diabetes, when breathing or low blood flow present potentially life-threatening physical challenges.

Blue Sharks Beat the Odds, by Tasting Bad

2008-09-02T00:14:00.000-07:00

Unpalatable, For Now

Although many sharks are experiencing population declines of up to 90 percent now, a new study on western North Atlantic blue sharks has found that numbers of the colorful species there are currently down, but not out.

Other reports had concluded that the region's blue sharks were declining by around 60 percent, but the new analysis reduced the estimate by half, finding that populations of the 12.5-foot-long sharks have dropped by only 30 percent since the mid 1950s, when large-scale fishing practices began in that part of the Atlantic.

Lead author Alexandre Aires-da-Silva told Discovery News that "the blue shark picture is not as 'catastrophic' as previously reported" for the western North Atlantic, bounded on the south by Cape Hatteras, N.C., and extending upwards to northern Newfoundland, Canada.

Aires-da-Silva conducted the study, published in this month's Fisheries Research journal, as part of his Ph.D. program at the School of Aquatic and Fishery Sciences at the University of Washington, Seattle. He and colleagues John Hoey and Vincent Gallucci used data on blue shark catch rates over five decades to develop an index of the shark's abundance.

Like archaeologists, the researchers dug through thousands of pages of vessel cruise reports that logged blue shark sightings. They also scoured field fishing logs, grant reports and many other historical sources, mostly from the historical archives of U.S. and Canadian fishery agencies.

Much of the documentation referred to sharks caught during long-line fishing for tuna and swordfish. The study concluded that blue sharks appear to be most vulnerable to swordfish fishing gear -- hundreds to thousands of baited hooks hanging from a single line. The lines are deployed at shallower depths at night after dusk, when the sharks feed.

Blue sharks sometime become by-catch, but since U.S. and Canadian consumers tend to not like the shark's taste, they haven't gone after the blue shark for its meat.

"In these countries, the blue shark meat has historically been regarded as unpalatable due to its soft texture and strong odor of ammonia, so that targeted fisheries did not develop," explained Aires-da-Silva.

Two other factors have helped the shark. The first is that they are rather hearty fish and often survive after being caught on a long line. The second is that blue sharks are among the most productive shark species in the world, with females producing an average of 37 pups per litter, with some litters numbering 80 pups or more.

"These pups can nearly double their size over their first year of life to increase their chances of survival," Aires-da-Silva said, adding that it "is not a coincidence that the blue shark has often been described in the scientific literature as the most widespread and abundant of the pelagic sharks in the world's oceans."

Enric Cortes, a National Oceanic and Atmospheric Administration research fishery biologist in Florida, told Discovery News that the new report "is a good, serious study" that used data sources that "are generally regarded as being more reliable than fishery-dependent data," the basis of earlier research.

Cortes said the findings "generally confirm what those who work on sharks know for this species: that it is one of the most productive sharks and that despite heavy exploitation, mostly for the international shark fin trade, the Atlantic populations seem to be in a fairly good state."

Both Cortes and Aires-da-Silva, however, warn that blue sharks are still vulnerable.

Aires-da-Silva said new fisheries directed towards the sharks have just emerged within the last decade, due to swordfish quotas in the Atlantic leading to greater focus on other targeted species.

Improved "blast-freezing" technologies onboard fishing vessels have also improved the processing and quality of blue shark meat, reducing the nose-holding ammonia quality.

Aires-da-Silve said blue shark meat now represents "a dominant proportion of the landings" in Spain and Portugal, where consumers, along with those in Italy, are developing a taste for the traditionally unpalatable sharks.

Coral-Wrecking Starfish Curbed by Fishing Regs

2008-09-01T04:35:00.001-07:00

Crown-of-Thorns Starfish

Two feet across, with 12 to 20 dark brown arms covered in inch-long spines, the crown-of-thorns starfish sweeps across Australia's Great Barrier Reef, devouring corals and leaving only chalk-white skeletons behind.

But new research suggests that fishing bans help control starfish outbreaks on the world's largest reef system.

Hugh Sweatman, of the Australian Institute of Marine Science in Townsville, Australia, used surveys of crown-of-thorns starfish on the Great Barrier Reef and overlaid them with the locations of no-fish zones.

The first no-fish zones, covering 4.5 percent of the reef, were established in 1989.

"The frequency of outbreaks on reefs that were open to fishing was 3.75 times that on no-take reefs in the mid-shelf region of the Great Barrier Reef where most outbreaks occur," Sweatman said.

Outbreaks of the starfish include hundreds of thousands of the coral-chompers covering miles of reef at a time. Once they polish off the corals on one reef, the starfish produce larvae that float to the next reef, propagating the outbreak.

Exactly how fishing bans reduce these outbreaks is not clear. Evidence that the protected fish control the starfish directly by eating them is scant, Sweatman said.

Is the World's Largest Shark Shrinking?

2008-09-01T04:33:00.000-07:00

The Incredible Shrinking Shark

- Humans have over-exploited the whale shark -- the world's largest living fish -- to such a degree that the ocean giants are actually shrinking in size, according to new research.

The whale shark population has also fallen by approximately 40 percent over the past decade in Western Australian waters, the new study has found, suggesting that this once prevalent shark, which can reach lengths up to 42 feet, is undergoing a severe decline in certain regions.

"We are all very alarmed at our findings, which really did defy our expectations," co-author Ben Fitzpatrick, a University of Western Australia biologist, told Discovery News.

The researchers analyzed the largest-ever database of sightings and size information on whale sharks. The database represents a long-term, continuous record of sightings -- 4,436 in total -- as well as photo ID information concerning age and size, all pertaining to whale sharks at Ningaloo Reef, Western Australia.

Because the sharks gather seasonally at the picturesque reef from March to June, a profitable industry has been built around "dive with sharks" activities. Usually by air sightings, tour operators regularly gather information on the sharks, compiled in the extensive database.

Fitzpatrick and his colleagues not only detected the population drop at the reef, but they also discovered the sharks have shrunk in body length by an average of over 6.5 feet. The overall reduction appears to be due to the disappearance of older, larger females, along with some males, within whale shark groups.

"I think it is mostly because the larger animals are being hunted for food and other products, such as for soup fins," explained Barry Brook, another co-author of the study and director of the Research Institute for Climate Change and Sustainability at The University of Adelaide.

"The larger the fin, the more valuable it is," Brook added.

The findings are published in the latest issue of Biological Conservation.

The scientists believe a selection effect may also be at work, whereby pressures are forcing smaller, younger whale sharks to breed earlier, but they believe this is just "a minor piece of the puzzle."

Whale Playground Sheds Light on Melting Arctic

2008-09-01T04:32:00.000-07:00

Bellwether Species

- A young whale pokes its melon-shaped head into the cool morning air near this remote island, a sign its herd is thriving despite mounting threats in Russia's melting Arctic.

Cameras and microphones capture the whale's every move as scientists use the species' only shore-side breeding ground to see how they are coping as fleets of oil tankers replace melting ice in their traditional feeding grounds.

"Belugas are a bellwether species...what happens to them reflects the effects of pollution and global warming on the whole ecosystem," said Vsevolod Belkovich, a professor at the Russian Academy of Science who is leading the study.

Scientists have recorded a small drop in the whale population that they attribute in part to human activity in Arctic regions. "As global warming continues, the threats are going to grow dramatically," Belkovich said.

Since monitoring began scores of whales have traveled hundreds of miles each year to this White Sea sandbank to mate, frolic and train their young.

Distinctive markings on the whales' backs allow the researchers to track the population from year to year, monitoring their health, longevity and interactions with rival herds.

"It's the only place in the world they come so close to the shore," said Vladimir Baranov, a senior researcher with Moscow's Institute of Oceanology, who films the Belugas close up underwater in their natural setting.

"They can play here because there is no danger," said Olga Kirilova, a fellow researcher. "But in the winter they go north and face intensive shipping, the tankers and their pollution."

Sea Turtles Dive to Depths for Reconnaissance

2008-09-01T04:31:00.001-07:00

Go Deep

- Researchers say they have figured out why sea turtles that normally feed and breed in shallow water or on land will, very rarely, go deep sea diving: the reptiles are on reconnaissance.

Scientists have long puzzled over why leatherbacks are built to plumb the icy depths.

Imagine someone donning a complete set of scuba gear -- tanks, buoyancy compensator, regulator -- only to paddle about the surface of a shallow lagoon. What's the point?

The mystery deepens. Not only are the turtles equipped with myoglobin-rich blood ideal for stocking oxygen, they sometimes plunge more than a kilometer (three-quarters of a mile) below the surface.

Jonathan Houghton and colleagues from the University of Swansea in Britain conducted experiments to find out why the lumbering sea creatures make these rare forays, and published their findings Friday in the British Journal of Experimental Biology.

The researchers fitted 13 leatherbacks with data loggers which recorded location, temperature, dive depth and duration, and transmitted the information to satellites as the animals surfaced.

Of more than 26,000 dives logged all across the North Atlantic Ocean, only 95 -- less than half of one percent -- went below three hundred meters.

Several theories have competed to explain these out-of-character deep dives.

Some researchers argue that the egg-laying reptiles go below to escape predators, while others speculate they simply want to cool off.

A third hypothesis is that the turtles are on the hunt for deep-sea delicacies.

But Houghton's findings suggest all these theories are off the mark.

A turtle trying to avoid becoming some fish's lunch would surely swim a bit more vigorously that usual, but the data collected indicates they were in no hurry as they plunged.

Moreover turtles spent several hours at the surface just before deep diving, probably to boost oxygen efficiency.

"Hanging out at the surface would be a daft strategy for avoiding predators, because that is where they can spot your silhouette," said Houghton.

As for keeping cool, temperatures don't drop much after the 350-meter mark, so there's little incentive to go any deeper.

But the food hypothesis, the study found, may be at least half right: even if the turtles don't eat the food they find at extreme depth, they probably find the food they will eat -- later on.

Leatherbacks like to dine on surface-dwelling jellyfish, but during the months spent travelling from their tropical breeding grounds in the Caribbean to cooler waters, they rely on jellyfish-like animals that form long colonies during the day at depths of about 600 meters.

The turtles, Houghton speculates, dive when the sun is out to find the colonies, and then wait form them to surface at night to begin feasting.

This would explain why the leatherbacks often loiter in the same area for days or weeks after such a deep dive, he said.

Female Guppies Risk Death to Avoid Males on the Make

2008-09-01T04:30:00.000-07:00

Fleeing Females

- Females from at least one other species besides our own will sometimes go to great lengths -- even putting themselves in harm's way -- to avoid sexual harassment by males, according to a new study.

Trinidadian guppies of the female persuasion, for example, would rather risk being eaten by predators that hang around with obnoxious males in search of sexual favors, the study found.

Biologists have long observed that females of numerous species will distance themselves from pushy would-be partners, but they have disagreed as to why.

At least one study has shown that when females are more vulnerable to attack -- because size or color, for example -- they may abandon prime feeding grounds, leaving the choicest morsels to males.

Another theory suggests that, for some species, the two sexes digest differently and thus wind up foraging or hunting in separate areas for different plants or prey.

In the case of the guppies, however, Safi Darden and Darren Croft, researchers at Bangor University in Wales, suspected that sexual harassment was the driving force of segregation.

"In nature, as a result of sexual conflict, females often experience harassment from males, which can be costly" for the females, they note.

To test their hypothesis, they devised an experiment with 240 wild guppies -- 120 large females, 60 small females, 60 males -- in a Trinidadian river, creating four zones subject to varying degrees of danger from fish-eating predators.

The results were unambiguous.

"In the presence of males, females actively select areas of high predation risk but low male presence, and thus trade off increased risk against reduced sexual harassment," they concluded.

Take away the males, and the females returned.

The study, published in the British Royal Society's Biology Letters, is the first experimental evidence that sex-adled males sometimes drive the objects of their ardor to flee, even into the jaws of danger, the authors say.

Octopuses Don't Have Eight Legs

2008-08-31T05:01:00.001-07:00

Not Just Arms, Legs Too

- How many legs does an octopus have? The answer should be easy. But not any more.

For new research suggests they are not really eight-legged denizens of the deep, as popularly assumed; instead they use their front limbs more like arms -- and can even tackle a Rubik's Cube.

Octopuses use their back two limbs largely for propulsion and use the front six for a variety of tasks, with the front two doing most of the exploratory work, said Alex Gerard, the curator of the Sea Life center in Brighton on the southern English coast.

Some 16 Sea Life center aquariums across Europe in Britain, Germany, Belgium, Finland, Ireland and the Netherlands studied their Giant Pacific, Common and Lesser Octopuses in coordinated tests.

"We've found that in all the tests, they do tend to favor particular limbs, which tends to give them a legs and arms sort of layout," Gerard told AFP Wednesday.

"Their front two tentacles will be used for a lot of exploratory work and then the ones immediately behind them will then be used also if further investigation is needed.

"Then the further back you go, the more the limbs are used for propulsion and movement.

"From what we've seen, all the limbs basically have the same capabilities. But they seem to favor this system and it works well for them.

"With live prey it does help them when sneaking up, with the front limbs ready to pounce and using the back ones for propulsion," he explained.

"They have that facility, unlike humans where if we tried to grab our food with our feet we might fail miserably."

However, he does not believe octopuses -- named after the ancient Greek for eight footed -- will have to be give a new name.

"The name's pretty good and they would have to rename James Bond movies," he said.

He added that though, like humans, some favor their left or right limbs more, "it just seems to be an individual preference".

Gerard conducted tests on Popeye, a Lesser Octopus at the Brighton center.

"Octopuses do have very strong personalities. They do develop their own favorite toys," he explained.

"My octopus hates the color red -- that's quite a natural response in nature -- but he particularly likes yellow. We're starting to build a profile for different octopus," Gerard added.

And during the tests, the octopuses got to play with some particularly challenging toys, namely Rubik's Cubes -- though none have managed to solve one yet.

"A happy octopus is one that's being constantly entertained," Gerard said.

"We wanted objects that would withstand an octopus exploring it but would also stimulate them. Things that were colorful were helpful.

"With a Giant Pacific Octopus, which is largest species in the world, it had ability to move sections of the Rubik's Cube."

The results are expected to be finalized and published in scientific journals.

Venomous Lionfish Prowls Fragile Caribbean Waters

2008-08-31T04:59:00.001-07:00

Alien Invaders!

- A maroon-striped marauder with venomous spikes is rapidly multiplying in the Caribbean's warm waters, swallowing native species, stinging divers and generally wreaking havoc on an ecologically delicate region.

The red lionfish, a tropical native of the Indian and Pacific oceans that probably escaped from a Florida fish tank, is showing up everywhere -- from the coasts of Cuba and Hispaniola to Little Cayman's pristine Bloody Bay Wall, one of the region's prime destinations for divers.

Wherever it appears, the adaptable predator corners fish and crustaceans up to half its size with its billowy fins and sucks them down in one violent gulp.

Research teams observed one lionfish eating 20 small fish in less than 30 minutes.

"This may very well become the most devastating marine invasion in history," said Mark Hixon, an Oregon State University marine ecology expert who compared lionfish to a plague of locusts. "There is probably no way to stop the invasion completely."

A white creature with maroon stripes, the red lionfish has the face of an alien and the ribbony look of something that survived a paper shredder -- with poisonous spikes along its spine to ward off enemies.

The invasion is similar to that of other aquarium escapees such as walking catfish and caulerpa, a fast-growing form of algae known as "killer seaweed" for its ability to crowd out native plants. The catfish are now common in South Florida, where they threaten smaller fish in wetlands and fish farms.

In Africa, the Nile Perch rendered more than 200 fish species extinct when it was introduced into Lake Victoria. The World Conservation Union calls it one of the 100 worst alien species invasions.

"Those kinds of things happen repeatedly in fresh water," Hixon said. "But we've not seen such a large predatory invasion in the ocean before."

The lionfish so far has been concentrated in the Bahamas, where marine biologists are seeing it in every habitat: in shallow and deep reefs, off piers and beaches, and perhaps most worrisome, in mangrove thickets that are vital habitats for baby fish.

Some spots in the Bahamian archipelago between New Providence and the Berry Islands are reporting a tenfold increase in lionfish just during the last year.

Northern Caribbean islands have sounded the alarm, encouraging fishermen to capture lionfish and divers to report them for eradication.

The invasion would be "devastating" to fisheries and recreational diving if it reached Puerto Rico and the U.S. Virgin Islands, according to Eugenio Pineiro-Soler of the Caribbean Fishery Management Council.

"I think at the best they will have a huge impact on reef fish, and at the worst will result in the disappearance of most reef fish," said Bruce Purdy, a veteran dive operator who has helped the marine conservation group REEF with expeditions tracking the invasion.

Purdy said he has been stung several times while rounding up lionfish -- once badly.

"It was so painful, it made me want to cut my own hand off," he said.

Researchers believe lionfish were introduced into the Atlantic in 1992, when Hurricane Andrew shattered a private aquarium and six of them spilled into Miami's Biscayne Bay, according to the National Oceanic and Atmospheric Administration.

Biologists think the fish released floating sacs of eggs that rode the Gulf Stream north along the U.S. coast, leading to colonization of deep reefs off North Carolina and Bermuda. Lionfish have even been spotted as far north as Rhode Island in summer months, NOAA said.

They are not aggressive toward humans, and their sting is not fatal. There are no estimates so far of tourists who have been stung. But marine officials say swimmers will be more at risk as the venomous species overtakes tropical waters along popular Caribbean beaches.

The slow-moving fish, which measures about 18 inches, is easy to snare, though lionfish swim too deep for divers to catch in nets -- a common method of dealing with invasive species.

So researchers are scrambling to figure out what will eat the menacing beauties in their new Caribbean home, experimenting with predators such as sharks, moray eels -- and even humans.

Adventurous eaters describe the taste of lionfish fillets as resembling halibut. But so far, they are a tough sell. Hungry sharks typically veer abruptly when researchers try to hand-feed them a lionfish.

"We have gotten (sharks) to successfully eat a lionfish, but it has been a lot of work. Most of our attempts with the moray eel have been unsuccessful," said Andy Dehart of the National Aquarium in Washington, who is working with REEF in the Bahamas.

One predator that will eat lionfish is grouper, which are rare in the lionfish's natural Southeast-Asian habitat. Scientists are pinning long-range hopes on the establishment of new ocean reserves to protect grouper and other lionfish predators from overfishing.

Hixon said there is some evidence that lionfish have not invaded reefs of the fully protected Exuma Cays Land and Sea Park, a 176-square-mile reserve southeast of Nassau. But unprotected locations in the vast archipelago are more vulnerable.

Containing the spread of the lionfish is an uphill fight. As lionfish colonize more territory in the Caribbean, they feed on grazing fish that keep seaweed from overwhelming coral reefs already buffeted by climate change, pollution and other environmental pressures.

Dehart said: "If we start losing these smaller reef fish as food to the lionfish...we could be in a whirlwind for bad things coming to the reef ecosystem."

In Shark Vs. Polar Bear Smackdown, Shark Wins

2008-08-31T04:52:00.000-07:00

Natural Born Enemies?

-- Adult polar bears, among the largest and most powerful carnivores, are thought to have no natural enemies, but that assessment might change in light of a polar bear jawbone recently found in the stomach of a Greenland shark.

While Greenland sharks, which can grow up to 24 feet long, are known to have eaten large seals, porpoises, an entire reindeer and parts of a horse, the discovery is rare evidence that they may also feast upon polar bears.

"These sharks eat anything they find dead, and do some active hunting as well," Kit Kovacs, who made the find, told Discovery News.

"We cannot determine whether the young bear was carrion or not -- nobody can," added Kovacs, who is the leader of the Biodiversity Research Program at the Norwegian Polar Institute in Tromso.

Kovacs made the unusual discovery while investigating the deaths of multiple harbor seals at Svalbard, an Arctic archipelago. She suspected that Greenland sharks, one of two species of sleeper sharks there, might be the culprits. Prevalent in the region, they are one of few species that might be capable of taking down polar bears, which grow to around 10 feet and weigh up to 1,500 pounds.

Kovacs and her team performed autopsies on collected Greenland shark specimens. They were shocked to find the polar bear bone, but in hindsight, she said, "this finding is not likely to be anything new."

"Greenland sharks have been in the Arctic for millions of years," she explained, suggesting that fatal encounters between marine and terrestrial predators would be inevitable over such an extended period.

"Habitat loss due to global warming is so much more important in terms of a threat to polar bears," added Kovacs.

It's even possible that climate change could have set the stage for the fatal encounter.

In recent years, scientists have reported that sea ice is melting in the Arctic at unprecedented rates. The International Union for Conservation of Nature and Natural Resources classifies polar bears as a vulnerable species, with global warming mentioned as the bear's most significant threat.

Seals make up the bulk of the polar bear diet, and the predators do most of their seal hunting on the ice.

At least one study, published in journal Polar Biology, found that the bears have become so desperate for food that they are now resorting to cannibalism.

Another climate change factor that could have made the shark-meets-bear encounter more likely is a documented growth of the Arctic sleeper shark population.

Aerial surveys have spotted hundreds of fins circling regions such as Prince William Sound off the south coast of Alaska.

Vince Gallucci, a University of Washington professor of fisheries and aquatic sciences, has studied shark populations for more than a decade. He believes the aerial count "would be a high number of sharks in one spot for any place in the world."

Climate change, regular regional climate shifts, and commercial fishing appear to have altered local ecosystems. The change appears to be hurting some animals, such as sea lions, but benefiting others.

"Sharks, being the more efficient eaters, just may be able to take greater advantage of changes in the food that's available," Gallucci explained.

Greenland sharks can descend to almost 1.5 miles underwater, so it is unclear if the Svalbard polar bear died, sunk and was snatched, or if the shark scavenged or killed it close to the water's surface.

Kovacs joked, "I won't be going swimming there again."

Lost Humpback Whale Calf Bonds With Yacht

2008-08-31T04:51:00.000-07:00

This One Knows Its Mum

- Australian media say a lost humpback whale calf has bonded with a yacht it seems to think is its mother.

The 1- to 2-month-old calf was first sighted Sunday in waters off north Sydney, and on Monday tried to suckle from a yacht, which it would not leave.

Rescuers towed the yacht out to sea, and the calf finally detached from the boat but still swam nearby, Australian Broadcasting Corp. and Channel 10 television news reported.

"It's very young, it still needs milk," a National Parks spokesman told Sydney's Daily Telegraph. "It's a very sad situation. Without its mother at suckling age, we are very concerned. There's no guarantee another pod will have a lactating mother and no guarantee it will accept it."

The calf appears exhausted but rescuers hope it will continue out to sea and search for its mother or another pod of whales.

"The outlook is not good, but we are giving the calf its only option. It can't be fed, and in fact we wouldn't know what to feed it" because it is not weaned, National Parks and Wildlife regional manager Chris McIntosh told ABC radio.

Imperiled Baby Whale Returns to 'Mama' Yachts

2008-08-31T04:49:00.000-07:00

- Fears were growing Tuesday for the survival chances of a lost baby humpback whale who tried to suckle from an Australian yacht in the belief it was its mother.

Wildlife experts used the yacht to lure the calf out of Pittwater bay near Sydney's Palm Beach on Monday, hoping it would link up with other whales passing by on their annual breeding migration.

But on Tuesday the calf was back among the anchored yachts in the vast bay, having failed to find either its own mother or a surrogate, Department of National Parks and Wildlife spokesman Chris McIntosh told AFP.

"We successfully lured the calf about a kilometer out to sea -- probably the first time that's been done using a yacht as a surrogate mother," he said.

"Later we saw whales a bit further offshore and there was a slender chance it may have linked up with them, but this morning we have got reports that it has returned to the western shores of Pittwater."

McIntosh said the calf now most likely faced the prospect of dying of hunger, being attacked by sharks or stranding itself.

"While it's moving quite freely at the moment, its condition would be expected to deteriorate over the next three days," he said. "There is very little hope, virtually none."

McIntosh said that if the calf became stranded or beached itself, mercy killing will be considered.

The calf showed no signs of injury, apart from some lacerations apparently caused by rubbing up against the boats, and it was believed likely to have simply been rejected by its mother.

"We've consistently said it was a slim chance that it might link up with its mother or other whales but the reality is that in the wild, for various reasons, mothers sometimes reject their young," McIntosh said.

The calf was estimated to be two months old, about five meters (yards) long and to weigh five tons, but it would still rely primarily on its mother's milk and its chances of survival without it were negligible.

"Looking at its behavior, the way it was nuzzling up to yachts, would indicate it was primarily still suckling," McIntosh said.

"It really was trying to suckle, just below the waterline and against the keel, with its head engaged against the boat."

It would be difficult to lure the calf out to sea again now that it had lost its strong attachment to a particular boat, and attempts to herd it would cause unacceptable stress, he said.

The humpbacks are on the return leg of a remarkable annual round trip from the Antarctic to tropical waters to breed, and they can be seen ploughing homewards not far off Sydney's beaches on most days.

Mexico Invests to Save Endangered Porpoise

2008-08-31T04:48:00.000-07:00

- Mexico said Wednesday it will invest 163 million pesos ($16 million) to save a highly endangered species of porpoise in the upper Gulf of California, asking reluctant fishermen to adopt safer methods or give up their trade entirely.

Scientists say the population of the vaquita marina -- Spanish for "little sea cow" -- has dwindled to 150 or fewer from more than 500 a decade ago.

Plans include paying fishermen to avoid the porpoise's habitat or give up drag nets that drown dozens of the shy, dolphin-like animals each year. Some will even be paid to stop fishing forever.

"We want to save a species at risk without putting humanity at risk," Environment Secretary Juan Rafael Elvira said at a ceremony kicking off the program.

Some US$13 million of the funds will go directly to families along the upper gulf. Working fishermen will be paid US$4,500 each to stay out of the nature preserve covering most of the vaquita's habitat.

Fishermen at the ceremony said the money would likely fall short of their lost revenues.

"We're participating to help save the species," said Oscar Javier Garcia, who agreed to keep out of the nature preserve if paid. "We're not convinced, but we're participating."

The government will also grant fishermen up to US$35,000 to learn safer techniques, such as catching shrimp with traps too small to ensnare the porpoises. Others will receive as much as US$60,000 for handing over their boats, motors and licenses and quitting the trade completely.

"It's a critical time for the vaquita, and the Mexican government has stepped up to the plate," said Peggy Turk Boyer, executive director of the Intercultural Center for the Study of Desert and Oceans, a U.S.-Mexican institution that will help survey the porpoise population this fall.

Also known as the Gulf of California porpoise, the elusive vaquita was only discovered in 1958. It rarely jumps from the water and avoids boats, making an accurate population count difficult.

The vaquita also is threatened by the dwindling flow of the Colorado River into the gulf. Depleted by western U.S. cities for drinking water, the river carries high levels of agricultural runoff that can significantly alter the gulf's chemistry.

Nemo Sniffs His Way Home

2008-08-31T04:41:00.000-07:00

Aug. 29, 2008 -- Tiny orange clownfish, made famous by the Disney character Nemo, use the smell of leaves and anemones in the water to find their way home on the coral reef.

That's the finding of a new study using a clever apparatus to measure the fishes' preference for water carrying different odors.

A team led by Geoffrey Jones of James Cook University in Townsville, Australia surveyed waters around Papua New Guinea for clownfish populations.

"The boat captain said, 'If you want to find the orange clownfish, you have to find islands. The fish need to see trees,'" said study lead author Danielle Dixson. The survey confirmed this observation: "There's a huge statistical difference [in the numbers of clownfish] between where there are islands and where there are not islands."

For reasons that are unknown, the two types of anemones that the region's clownfish call home only live near islands with trees and beaches and are not found on "islands" made only of reefs.

But the fish have to search for these anemones, because after eggs hatch near the parents' home anemone, the larvae are carried away by ocean currents. About 11 days later, the juvenile fish settle back into a new anemone, somehow having found their way to their favored abodes.

The researchers set out to figure out how.

They used a chamber with two sources of water flowing side by side. At the top, a wall divides the chamber, separating the water sources. Lower down, the wall disappears, but the water remains unmixed, with the two types of water flowing parallel to each other.

The researchers introduced clownfish into the chambers and measured how much time they spent on either side. This allowed the researchers to test the fishes' preference for water from different sources.

First they compared beach water from near vegetated islands with water from reef islands.

"It was ridiculously high how attracted they were to the beach water," said Dixson. The fish spent more than 99 percent of their time on the side of the chamber with beach water flowing by.

"The next step was to figure out what is in the beach water that is making them able to discriminate beach water from the other," she said.

Researchers have previously shown that clownfish are attracted to a chemical cue from anemones, and the team found that the fish strongly preferred water that had been exposed to anemones versus water that had not.

But the signal from anemones is unlikely to travel very far, so the team wondered whether there were other cues that could draw the fish back to the islands.

"The islands are loaded with trees," Dixson explained, and the water nearby has large numbers of leaves floating on the surface. So, the team exposed ocean water to five different kinds of leaves from the islands, and to a mixture of the leaves, and compared those to ocean water with no leaf exposure. "They were attracted to all of them."

But they were not attracted to the tea tree plant, which grows in swamps nowhere near the islands, so the fish have specific preferences for the "right" kind of trees.

Finally, the team showed that even fish bred in aquariums in synthetic seawater were attracted to beach water and to anemone and leaf cues, suggesting that this attraction is innate.

"The results are just spectacular," said Jelle Atema of Boston University who developed the testing chamber for his own research and shared one with the Jones group. "As humans we don't take very seriously the notion of odor in water. It's very foreign to people: How can you smell in water?"

Jelle agrees with the researchers that the abundance of leaves in the water near these islands serves to bring the fish into the right vicinity, after which they can search out the anemones.

Beyond providing an example of animal abilities, the research also has a broader message.

"It shows that there is a connection between the marine and the terrestrial environment," Dixson said. "It shows that the two can't be treated separately, especially in terms of management."

"If you're trying to protect the reef, but you're not protecting the shoreline that calls these 'Nemos' home, it's not going to work," she said.

Calcium and Alkalinity: Methods to Achieve Proper Levels

2008-08-31T04:37:00.000-07:00

One of the aspects of keeping small polyp stony (SPS) corals that is starting to gain significant attention is the need to supplement calcium by the easiest means possible. Before stony corals were maintained, little attention was paid to maintaining the proper level of calcium. Water changes and the dissolution of the calcium substrate were thought to be able to keep the levels high enough, so that no additional supplementation was utilized.

When the Berlin System for keeping corals was introduced in the late 1980's, the concept of supplementing calcium in the tank was first described. This was important, in that prior to this series of articles, little attention was paid to the coral's need for calcium in order to thrive and grow. Initially, the only method described was that of using calcium hydroxide dissolved in water (kalkwasser) to replace evaporated water. As tanks became more sophisticated and stony corals and clams became the dominant animals in these tanks, more sophisticated methods for maintaining calcium levels have been developed. Over the past ten years, it has finally been demonstrated that virtually all corals, as well as coralline algae require calcium in order to thrive.

The reason that no single method of calcium supplementation is utilized exclusively is that, to date, no system has proven to be perfect. Despite the shortcomings of these methods, it is still relatively easy to maintain the calcium level in most tanks above 400ppm (parts per million), the level of natural seawater, as long as these problems are understood and managed. It is very important that calcium levels be kept this high, particularly for stony corals, for these reasons:

If calcium levels are low, the corals will not grow, and what little growth does occur, will result in thin, spindly branches.
In addition, if growth is not occurring, the coloration of the coral, particularly at the tips, will not be as vivid as when the coral is growing well.

It is necessary to understand the limits of each method of supplementation before choosing a method for one's system. The methods that are currently being employed include:

Calcium chloride and buffer
Kalkwasser (sometimes referred to as limewater)
Kalkwasser reactor
Balanced liquid or dry supplements
Calcium reactors
Calcium reactor and kalkwasser combinations

I have used each of these methods over the past ten years, so I feel comfortable discussing their advantages, as well as their shortcomings. However, I do not consider myself an expert on calcium supplementation, as I am still tinkering to try and optimize my calcium supplementation system.

Note: In nature, seawater bathes coral reefs in many minerals and elements. Of all the minerals and elements present in natural seawater, no mineral is consumed as quickly or in as large amounts as calcium. Hard corals, which are the building blocks of the coral reef, demand large amounts of calcium to build their skeletons. Providing enough calcium to meet the demands of all the corals, invertebrates, and algae in a closed ecosystem creates a real challenge for the hobbyist.

Largest Squid Ever Caught Is "Giant, Gelatinous Blob"

2008-08-28T23:44:00.000-07:00

Armed with giant tentacles, swiveling hooks, and the world's largest eyes, the colossal squid is thought to be the biggest squid species and the source of centuries-old sea monster myths. But the largest squid ever caught was "a giant, gelatinous blob," sluggish and highly vulnerable to predators, a squid expert who dissected the specimen said last week.The dissection of the half-ton female at a New Zealand museum in April suggests she was an egg-producing machine, which—like most squid—would probably have given birth once before dying, said Steve O'Shea of New Zealand's Auckland University of Technology.

The 30-foot-long (10-meter) squid, snagged on a fishing line off Antarctica in 2007 (photos), carried some partially developed eggs. But when fully mature, he said, she would have had "many, many thousands of eggs" inside her mantle cavity, a chamber inside her tubular upper body.

That may explain why she had been scavenging from fishing lines, rather than actively hunting.

Not-So-Colossal Cousin

O'Shea stressed that much of his work was still theoretical.

"Life cycles, reproductive strategies, egg brooding, all the behavior of these things is basically unknown, so we've got to make do with the most closely related example for which we have more information."

That example, he said, is Teuthowenia pellucida, "a small-bodied colossal-squid equivalent in New Zealand waters," he said.

Though it grows to only about 8 inches (20 centimeters) long—versus the colossal squid's estimated 50 feet (15 meters)—Teuthowenia is "basically identical," O'Shea said.

Female Teuthowenia that have mated carry "very large eggs" in their mantle cavities.