duminică, 31 august 2008

Octopuses Don't Have Eight Legs

Not Just Arms, Legs Too
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

Red Lionfish
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

Shark vs. Polar Bear
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

This One Knows Its Mum
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

Dangerously Confused

- 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

At Risk

- 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

Keen Sniffers

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

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.

joi, 28 august 2008

Largest Squid Ever Caught Is "Giant, Gelatinous Blob"

colossal giant squid caught: photo

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.