Species Extinctions Overestimated by 160 Percent?

Global extinction rates may have been overestimated by as much as 160 percent, according to a new analysis.

In recent decades numerous studies have predicted thathabitatdestruction will doom some 20 to 50 percent of Earth's species within 500 years.

(See"By 2050 Warming to Doom Million Species, Study Says.")

It's true that many species are still dying off, but the decline is happening at a slower pace than generally feared, according to study co-authorStephen Hubbell, an ecologist at the University of California, Los Angeles.

"The good news is that we may have a little more time in terms of saving some species,"Hubbell said.

The bad news, he stressed, is that surging extinctions driven by habitat loss remain the critical conservation problem of the 21st century.

Method for Measuring Extinctions Flawed?

There's no proven, direct method for verifying extinction rates, so most scientists have relied on an indirect method to estimate how quickly plants and animals are disappearing.

That method calculates the rate at which new species are found when a new habitat area is sampled—called the species-area relationship (SAR)—and simply reverses that curve to predict the number of species that will go extinct as similarly sized areas of habitat are destroyed.

(See"Extinction Crisis Worsens: 'Dow Jones' Approach Touted.")

But Hubbell said the method is flawed, because much more land area must be lost to cause an extinction than is required to find a new species.

That's because only one individual of a species needs to be found in an area for scientists to deem it a new population, but extinction requires every member of a species to disappear.

"It's equivalent to saying a species is committed to extinction if you find the first individual and destroy its habitat, and that's clearly not true,"Hubbell said.

"You have to destroy all of the habitat that has all the individuals of a species in it before that species goes extinct."

Hubbell and colleagueFangliang Heof Sun Yat-sen University in Guangzhou, China, analyzed data from eight previously mapped forest areas from around the world. Each plot was between about 50 and 125 acres (20 and 50 hectares). The team also looked at ranges of severalbirdspecies in the continental United States.

Based on this real-life data and a mathematical model—in which the hypothetical destruction of habitat always resulted in fewer extinctions than predicted by SAR—the scientists calculated that the SAR-derived extinction rates had been overstated by as much as 160 percent.

The team also suggested that future studies could reveal even higher overestimates in some places.

Habitat Loss Still a Threat to Species

Yet ecologistEric Dinerstein, who wasn't involved in the new study, said that examining how extinction rates are calculated is a bit of an academic argument for many conservationists.

"If it's a 160 percent overestimate or an 80 percent overestimate or a 20 percent overestimate, {comparing} which model of extinction rates is more accurate isn't the most important question,"said Dinerstein, vice president of conservation science for WWF, a global conservation group.

(See"One in Four Mammals at Risk of Extinction.")

"The overpowering message is that habitat loss and fragmentation are still the greatest threat to the future of species, and they are only increasing."

Dinerstein added that it's hard to determine when a species has gone extinct, as evidenced by numerous animals once thought gone but later found alive in small numbers.

(Seephotos:"Bubble-nest Frog, Other 'Extinct' Species Found.")

And the final extinction of a species may be beside the point, Dinerstein said. What really matters is ecological extinction.

"That's when a population drops below a certain number of individuals and is no longer playing an ecological role in the ecosystem,"Dinerstein said.

At this point the diminished species has so little interaction with the other plants and animals in the habitat that the species might as well be gone, from the point of view of the ecosystem.

Ecological extinction is of"much more concern to conservationists than {identifying} the last one or two individuals of some species which are still {alive} but functionally extinct."

Extinction Rates Critical for Conservation

Hubbell and He stressed that their research doesn't change the big picture, which isn't particularly rosy for species survival.

"I think {scientists and conservationists} are right in saying that we're really on the cusp of a sixth mass extinction or that it's actually in progress. We certainly don't disagree with that assessment,"said Hubbell, whose study appears May 19 in the journalNature.

(Read about mass extinctions throughout history.)

But he also noted that learning how to calculate extinction rates properly is critical for conservation.

Take extinction-rate estimates by major initiatives, such as theIntergovernmental Panel on Climate Changereports and the U.N.'sMillennium Ecosystem Assessment.

If such estimates"are going to have consequences for billions of dollars in conservation efforts, don't you think we ought to know better why we're spending money and what the actual numbers are?"Hubbell said.

Co-author He also told reporters during a press briefing that no other scientific activity is arguably more important than understanding the causes and consequences of species extinctions.

However, He and Hubbell added that determining extinction rates has a long way to go.

"The bad news is that we really don't have good methods for estimating extinction yet,"Hubbell explained.

"The precise answer depends on the precise pattern of habitat destruction in relation to the precise distribution of species.

"And although we can look at habitat destruction from satellites, we often just don't know where species live on the ground."

forNational Geographic News

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Pictures: See-Through Frog, Other"Lost" Species Found

Bursting with eggs, a pregnant frog with see-through skin is one of five"lost"amphibianspecies recently rediscovered inthe Democratic Republic of the Congo (DRC).

First described in 1950,Hyperolius leucotaeniuswas recently found on the banks of the Elila River in southeastern DRC.

The status of the five species, first described between 1950 and 1952, was a mystery until they were rediscovered during the recent field expeditions, which took place between 2009 to 2011.

"Like most of the 'lost' amphibian species, they simply hadn't been seen for many decades, and their status was completely unknown,"expedition leaderEli Greenbaum, a biologist at the University of Texas at El Paso, said by email.

The DRC expeditions were inspired byConservation Internationaland theInternational Union for Conservation of Nature's 2010effort to rediscover a hundred"lost"amphibian species around the world (see pictures).

That unprecedented effort focused primarily onfinding ten species of high scientific and aesthetic value. Ultimately, scientists on that project spotted only 15"lost"species, and just one from their most wanted list.

The newly announced discovery of the DRC frogs"is good news,"according to Greenbaum, whose work was partially funded by the National Geographic Society'sCommittee for Research and Exploration. (The Society owns National Geographic News.)

"My team's discoveries confirm that those jungles have been poorly explored,"he said in a statement."There is a lot of biodiversity there, and it's not too late to redouble our efforts at conservation."

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Tarantulas Shoot Silk From Feet, Spider-Man Style

Tarantulasshoot silk from"spigots"in their feet to climb slippery surfaces, a new study says.

Keeping balance is crucial for the delicate arachnids, which would likely die in a fall. So tarantulas often use silk much like Spider-Man does when wall-crawling—to stick to surfaces and stay firmly attached, even when the ground is shaky, the research confirmed.

Tarantulas don't spin typical spider webs, but often use their silk to line or protect their burrows.

(See"Spider-Man vs. True Spider Superpowers.")

The silk-slinging theory was first put forth in 2006, but scientists have been divided on whether tarantulas shoot silk from their feet, or if they grab silk from their spinnerets—silk-producing organs—and use that as a glue.

To resolve that question, the University of Newcastle'sClaire Rindand undergraduate student Luke Birkett put tarantulas into a clean, dry fish tank lined with microscope slides. While filming with a video camera, the team tipped the tank on its side so that the spiders either stayed put or slipped just a bit.

Watching the footage in slow motion revealed that only the spiders' feet had touched the glass, and that the spiders slipped only slightly.

They also examined the slides to look for any evidence of silk secretions, Rind said."On the slides where the foot was found, we found 20 or 30 silken threads in the footprint."

Spiky Silk Spigots Observed for First Time

Rind also studied tarantula feet under an electron microscope and found tiny silk-producing spigots intermingled with the hairs on the spiders' feet.

(Watch a video of the world's largest spider.)

Each fuzzy hair looked like a"loo brush,"said Rind, while every spigot resembled a"small spike."

Rind saw silk threads still coming out of the spigots—contradicting previous studies that had found that the spikes are sensory structures.

She observed three different species of tarantula under the microscope: the Chilean rose, the Indian ornamental, and the Mexican flame-knee tarantula.

These species are"about as far away as you could get from another on the tarantula tree,"so it's likely that all tarantula species possess this silk-slinging ability, Rind said.

(See"Untangling Spiders' Evolutionary Web.")

The Mexican flame-knee tarantula was studied via its molted exoskeleton, which incidentally came from Rind's pet tarantula, Fluffy, who had died before she could participate in the experiments.

But that's OK by Rind:"She was not the best-behaved lady ... a bit aggressive."

The tarantula-silk study will appear June 1 in the journalJournal of Experimental Biology.

forNational Geographic News

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Mississippi Flood Pictures: Pets, Wild Animals Seek Safety

Robert Sanders rows past his Holly Grove,Arkansas, home atopMississippi Riverfloodwaters Tuesday with hisdog—aptly named Lucky. Many pets along the Mississippi River and its tributaries are at risk as the river swells, according to a Wednesday statement by the Humane Society of the United States (HSUS).

"The HSUS is prepared to temporarily shelter any animal displaced by the floods; please remember, if it is not safe for you, it isn't safe for your pets,"said Lydia Sattler,Mississippistate director for the HSUS.

Earlier this week, the Mississippi River peaked in Memphis, Tennessee, just inches below the all-time record, according to the National Weather Service. Now the surge is continuing south toward the Gulf of Mexico, where New Orleans is bracing for its own crest around May 23.

—With reporting by Brian Handwerk

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Mississippi Flood Flushes Snakes, Deer Into Neighborhoods

The currentMississippi Riverflood is flushing snakes,deer, and other wild animals out of their natural habitats—and, in some cases, into homes and neighborhoods, officials report.

(SeeMississippi flood pictures.)

AtMemphis (map),Tennessee,the Mississippi crested late Monday at 47.8 feet (14.5 meters)—less than a foot below the city's record, set in 1937.

With the river now receding in the city and the rest of Shelby County, nature has"put the pin back in the grenade,"said county spokespersonSteve Shular.

But explosive animal encounters may await returning evacuees.

"We're starting to see some issues, especially with the snakes,"Shular explained."We've definitely seen a lot of snakes, likewater moccasins {picture}"—venomous pit vipers with potentially fatal bites that are also called cottonmouths.

With swollen rivers reaching up near homes and neighborhoods,"we want to make sure people understand that the rules have changed,"Shular said.

"When that water gets into a neighborhood, snakes are going to be searching for shelter and food in homes or sheds or wherever they can slither into."

Floods Come at Tough Time for Turkeys

But isn't just snakes displaced by the flooding, according toTennessee Wildlife Resources Agencyofficer Jereme Odom.

With thousands of acres of farms and wooded bottomlands flooded, countless rabbits, turkeys, deer, and other animals have been forced to flee—or perish.

"We've seen photos of herds of deer on levees trying to get away from the waters and heard from the Army Corps of Engineers that they've seen deer drowned during the flood,"Odom said.

"One of our wildlife managers even spotted deer andcoyotes"—natural enemies—"standing on the same levee together,"he said.

The floods come at a particularly poor time forwild turkeys, Odom added, because most of thebirdsare nesting at this time of year.

Many of those nests have been lost to or displaced by floods, and countless new birds might not survive—especially if the nests float to areas with egg-eating opossums orraccoons.

"In the flooded areas, we're going to see a significant reduction in turkeys,"Odom said.

(Related:"Mississippi Floods Can Be Restrained With Natural Defenses.")

Mississippi Flood Spurs Tide of Animal Refugees?

While most animals will survive the Mississippi River flood, for some their habitats could take years to return to normal, Odom said.

"Animals will be displaced for so long that, when the water does recede, it will take a while to get back to their original habitats,"he said."Some may be established elsewhere or displaced so far away that they never get back."

Finding food and shelter in the unfamiliar new surroundings could be stressful, Odom said. And the new neighbors may not exactly roll out the welcome wagon.

"Snake populations, in particular, could be really {threatened}, because when they get into residential areas, people just destroy them,"he said.

Hoping to avoid unnecessarily contentious encounters, the Tennessee Wildlife Resources Agency is advising people, whenever possible, to simply wait for animals to return to their normal habitats.

"Animals that appear to be in need of rescue should be left alone,"Chad Harden, a big game coordinator with the agency, said in a May 6 statement.

"They are under stress, but their natural survival instincts will help them cope with the situation until things get back to normal. The animals could pose a real danger to someone who might try to rescue them."

For his part, Tennessee wildlife officer Odom is taking the long view.

"This isn't the first time we've seen major floods. It goes all the way back toNoah, and the animals are still here,"he said."The main thing is what humans will do to let them come back."

forNational Geographic News

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New Species of Tiger Stingray Named

An Amazonstingrayknown as the tiger ray has finally earned its scientific stripes: It's been officially recognized as a new species.

For more than a decade, aquarium traders in the upper Amazon River Basin ofPeruhave caught the freshwaterfish, whose name—Potamotrygon tigrina—is inspired by its orange-black coloration and banded tail.

Up to 31 inches (80 centimeters) wide, the species is distinct from other stingrays based on, among other features, its conspicuous colors and its tail spines, which are lower and not as closely grouped as those of its relatives.

(See relatedpictures:"Odd Stingless Stingrays Discovered in Amazon.")

"It's one of the prettiest species,"saidMarcelo de Carvalho, a zoologist at the University of São Paulo in Brazil who led a new study on the tiger ray.

Tiger Ray's Patterns a Mystery

WhyP. tigrinais so striking compared with the bland browns and tans of other stingrays is still a mystery, de Carvalho added.

For instance, the stripes could be warning coloration—although most Amazon freshwater stingrays have few predators, other than the occasional crocodile.

"It's kind of ungainly to fit into the mouth of another fish,"he said.

Overall there's virtually nothing known about the tiger ray—in fact, aquarium traders who catch them in the wild or breed them in captivity probably know much more about their biology than most scientists, he added.

P. tigrinais one of the most popular types of pet rays in Asia, especially in Japan and China. (Seea giant freshwater stingray caught in Asia.)

Giving the animal a formal species classification"is the first step in understanding how we can regulate this resource,"de Carvalho said.

The tiger-ray study appeared April 21 in the journalZootaxa.

National Geographic News

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Whales Throng New York City Area, Surprising Scientists

It turns out a lot of big whales have a taste for the Big Apple area, including the 100-foot (30-meter)blue whale, the largest animal on Earth, scientists say.

A network of ten underwater sound recorders in place off the length of the south coast ofLong Island and throughout New York Harbor (map)between 2008 and 2009 detected a surprising density of ocean giants across an unexpectedly vast area, experts say.

These"open mikes"picked up the ballads of the fin whale, blue whale,humpback whale, minke whale, sei whale, and the rare North Atlanticright whale, said Christopher Clark,Bioacoustics Research Programat the Cornell Lab of Ornithology in Ithaca,New York.

The fin, humpback, right, and sei whales are on the U.S. endangered species list, meaning the federal government considers them to be"on the brink of extinction."

(See whale pictures.)

But what amazed the team the most was not the types of whales heard, but the sheer density of animals spread out over the entire study area, said Aaron Rice, science director of the bioacoustics lab.

For one thing, the scientists were struck by the"juxtaposition of having such large charismatic animals that represent ocean biodiversity living right off of the largest city on the Atlantic coast,"Rice said

Some of the whales cruised as close as 10 miles (16 kilometers) fromNew York City, he said.

Clark said,"If you were standing at the top of the Statue of Liberty and looked south or southeast, if you {could see} under the water, there were whales singing under the surface."

In some cases, it was the whales' distance both near and far from shore that surprised the researchers.

For instance, the recorders picked up songs of the North Atlantic right whale 70 miles (113 kilometers) from shore—where the coastal dweller isn't thought to venture.

The acoustic technology, however, does not yet allow the scientists to accurately estimate exactly how many whales they heard.

Science director Rice said,"Now that we know they are there, our next question is how many."

Motormouth Whales

Whales communicate mostly by sound, and each whale species has a distinct call, Rice said. This made it easy for scientists to identify which species had been recorded, he said.

(Also see"Salmon in the City: Fish Return to Paris River.")

Some of the whale species were migrating through New York on the way to feeding grounds farther north, while others tend to stick around the coast throughout the year, Rice said. Occasionally a whale will wander all the way into a harbor and attract media attention.

Overall, the acoustic monitoring is part of a larger project to understand what sorts of human-made sounds exist along the U.S. East Coast, and how these sounds may impact whales long-term, Rice said. (Related:"Killer Whales Strain to 'Talk' Over Ship Noise?")

Acoustic recording has proven a dependable technique for tracking the mammals—especially because"it's really hard for whales to keep their mouths shut,"Clark quipped.

City-whale findings were presented May 4 at a Cornell University press luncheon in New York City.

National Geographic News

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Biggest Great White Shark Caught, Released

ON TV:Shark Men—Biggest and Baddestpremieres at 10 p.m. ET/PT on Sunday, May 8, on the National Geographic Channel.

Talk about a bigfish—an expedition crew has hauled up—and released—what the team says is the biggestgreat white sharkyet caught.

The 17.9-foot-long (5.5-meter-long) male behemoth was found offMexico'sGuadalupe Island (map)in fall 2009.

The animal breaks the team's previous record of 16.8 feet (5.1 meters), set when they caught a female great white named Kimel. (Both records are unofficial and not maintained by a formal organization.)

The new titleholder was named Apache after the dog of Brett McBride, boat captain on the National Geographic Channel showShark Men.(The National Geographic Channel is part-owned by the National Geographic Society, which owns National Geographic News.)

Shark Menchronicles the work ofscientists and fisherswho catch and release great whites in an effort to figure out where the mysterious giants breed and give birth. The scientific team is led by Michael Domeier, president and executive director of theMarine Conservation Science Institute.

The two-ton Apache put up a fight—at one point breaking free from his barbless hook, said expedition leaderChris Fischer.

"The battle with Apache was like nothing we've ever dealt with,"Fischer said.

Once on board, the researchers fitted the fish with a satellite-tracking tag, took a blood sample, and released him, watching him vigorously swim away.

(See relatedpictures:"'Shark Elevator' Lifts Great Whites From Sea.")

"He was all scarred up and had big marks all over him—you could tell he was just a bad-ass shark,"Fischer said.

"It was so impressive and so humbling to be near him."

Size Doesn't Matter for Shark Research

In large ocean fish species, females are almost always bigger than males, because they need more girth to carry their young, Fischer noted. (Seegreat white shark pictures.)

However, even a male of Apache's size is not unheard of among great whites, other experts say.

"That is one big shark, {but} I have no doubt that this isn't the largest white shark in the wild,"John O'Sullivan, head of theMonterey Bay Aquarium's White Shark Program, said by email.

Shark expert Kenneth J. Goldman added,"I don't see anything overtly magnificent about it being so large. It's just another adult male they've tagged."

That's because size alone doesn't tell scientists much, said Goldman, a fishery research biologist at theAlaska Department of Fish& Gamein Homer.

Instead, Apache's real value would be in helping to resolve the lingering mysteries of great white behavior.

Biggest Shark May Help Crack Mysteries

Expedition leader Fischer agrees—and he and his team are now watching to see where Apache goes.

For instance, recent research suggests that Pacific great whites gather in specific spots near the coasts—including the Guadalupe Island site—and thentravel to a"cafe"in the middle of the ocean to feed. The animals often return to the same aggregation sites after feeding.

But this is still a tentative theory, so it"would be groundbreaking if, {say}, Apache left Guadalupe and went to the middle of the ocean and {returned} to a different aggregation site,"Fischer said.

(See"Great White Shark Filmed Breaching at Night—A First.")

Overall, tagging sharks to figure out where they migrate and congregate may help conservationists protect the species, Fischer added. Great whites are considered vulnerable by the International Union for Conservation of Nature.

Meanwhile, Apache lives on, he said, as a"giant male shark out there doing his great white thing."

National Geographic News

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Sea Urchin Body Is One Big Eye

Sea urchins may use the entire surfaces of their bodies—from the ends of their"feet"to the tips of their spines—as huge eyes.

Scientists had already known the marineinvertebratesreact to light without any obvious eye-like structures—raising the question of how the animals see.

(Also read:"Eyes Made of Rock Really Can See, Study Says.")

Previous genetic analysis of the California purple sea urchin had revealed that the animals possess a large number of genes linked with the development of the retina—the light-sensitive tissue lining the inner eyeball in people and other vertebrates.

This and other research suggested thatsea urchin vision might rely on light-receptor cells randomly scattered across their skin, which collectively function like retinas.

Scientists had theorized the animals' spines simulate the light-blocking pigmented cells found in most animals' eyes. Because light-receptor cells in the retina can soak up light from every direction, pigmented cells work to block light from the back and the sides so animals can"see"what's in front of them.

Now, however, the scientists have found two distinct groups of bristly, light-receptor cells concentrated at the bases and tips of the purple sea urchin's 1,400-plus tube feet. These long, suction-tipped tubes, located on the undersides of sea urchin bodies, help the organisms move.

The team suspects that sea urchins use their tube feet as retinas and the rest of their bodies to shield against the extra incoming light, said researcherMaria Ina Arnone, a developmental biologist at Anton Dohrn Zoological Station in Naples, Italy.

Prior studies did find the number and placement of spines on a sea urchin could affect how sharp its vision might be, and this new find"might well be part of the picture,"Arnone added.

The sea urchin-eye study appeared May 2 in the journalProceedings of the National Academy of Sciences.

forNational Geographic News

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Giant Squid Killed by Sound?

Whengiant squidwere found dead offSpainabout a decade ago, scientists suspected that powerful sound pulses from ships had harmed the animals. Now the evidence may be in.

A new study says low-frequency sounds from human activities can affect squid and other cephalopods, not just whales and other marine mammals, which have long been thought to be vulnerable to such pulses. (See"U.S. Navy Sonar May Harm Killer Whales, Expert Says.")

The finding suggests noise pollution in theoceanis having a much broader effect on marine life than previously thought, said study leader Michel André, a marine bioacoustician at Barcelona'sTechnical University of Catalonia.

"We know that noise pollution in the oceans has a significant impact on dolphins and whales {which use natural sonar to navigate and hunt}. ... but this is the first study indicating a severe impact on invertebrates, an extended group of marine species that are not known to rely on sound for living,"André said in a statement.

(Related:"Colossal Squid Has Glowing 'Cloaking Device,' Huge Eyes.")

Giant Squid Mystery Solved?

In the early 2000s the remains of giant squid were found off Spain'sAsturias province (map). In each case, the creatures' bodies appeared soon after ships had used air guns to conduct low-frequency sound-pulse exercises in the region, in some cases for oil-and-gas prospecting efforts.

Scientists investigating the giant squid remains at the time found evidence of extensive bodily damage, including mantles reduced to pulp, bruised muscles, and lesions in statocysts. These fluid-filled organs rest behind the creatures' eyes and help giant squid maintain balance and position. (Seepictures of a colossal squid dissection.)

At the time, marine biologist Angel Guerra speculated—but was unable to prove—that noise from prospecting ships was harming cephalopods and other marine life.

"With this study, we now have proof"that low-frequency sounds can harm cephalopods, said Guerra, a marine biologist at Spain'sMarine Research Institutewho was not involved in the current study, which will appear in a future issue of the journalFrontiers in Ecology and the Environment.

(See rarepictures of sperm whales eatiing a giant squid.)

Damage Worsened With Time

During the study, the research team examined the effects of low-frequency sound exposure in 87 individual cephalopods belonging to four species: two species of squid, one species of octopus, and one species of cuttlefish. (See"Cuttlefish Change Color, Shape-Shift to Elude Predators.")

For two hours the animals were exposed to sound with intensities of between 157 and 175 decibels and frequency ranges of 50 to 400 Hertz.

These frequencies and intensities"are commonly found in the noise produced by many activities at sea,"such as military sonar tests or efforts to detect oil and natural gas by gauging the nature of material beneath the seabed, the Technical University of Catalonia's André told National Geographic News.

After the sound exposure, the scientists killed the animals, either immediately or up to 96 hours afterward.

The animals that were killed immediately after exposure showed signs of damage to their statocyst tissue. Specifically, tiny hairlike structures in statocyst cells—which bend as the cephalopods move through water and help the animals balance—were lost, essentially crippling the creatures.

The animals allowed to live longer showed further damage, including large, visible holes in the statocyst tissue.

"This is a typical process found in land mammals and birds after acute noise exposure: a massive acoustic trauma followed by peripheral damage, making the lesions worse over time,"André said.

In their final seconds or hours, the test cephalopods"moved a little bit, but they were not swimming, eating, or mating,"André said.

A separate group of about a hundred cephalopods was not exposed to the pulses. They remained healthy and behaved normally.

Both groups had been kept in the same aquariums before being separated, and all the animals had behaved normally before the tests—ruling out the possibility that the damage observed in the test group was due to captivity or human handling, he said.

(Pictures:"Giant Squid Get Extreme Plastic Surgery.")

"Raise the Alarm"for Giant Squid?

Though the cephalopods in the experiments were much smaller than giant squid, the experiments represent"the same phenomena as with the giant squid,"the Marine Research Institute's Guerra said.

The test animals are appropriate stand-ins for their giant squid cousins, according to Guerra, who said he sees no reason why the findings wouldn't apply to giant squid.

There are some differences in the damage, though.

The injuries to the giant squid found last decade, he noted, were much more pronounced than in the experimental animals. Guerra attributes this to the higher acoustic intensities and multiple sound sources giant squid are exposed to in the real world.

And of course, the giant squid were found not just injured but dead, unlike the test animals. But scientists say the case of the giant squid off Spain suggests death is one possible outcome of exposure to low-frequency blasts.

At the time of the giant squid deaths,"we hypothesized that the giant squid died in one of two ways: either by direct impact from the sound waves or by having their statocysts practically destroyed and {the squid} becoming disoriented,"Guerra explained.

"The disoriented animals might wander up from the depths to the surface, where the temperature difference kills them."

Marine zoologist Michael Vecchione, of the U.S. National Oceanic and Atmospheric Administration (NOAA), isn't yet sure.

Though the new research presents enough evidence to"raise the alarm,"more studies are necessary before a solid case can be made that human-caused noise pollution is causing pervasive damage to marine life, said Vecchione, who also did not participate in the study.

But, he added,"the evidence is accumulating that what {Guerra} first proposed based on the giant squid might actually be correct."

More:Alien-like Squid With 'Elbows' Filmed at Drilling Site>>

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Wild Pig Explosion May Spread Disease to Humans

An explosion of wild pigs in the U.S. could be exposing people to dangerous parasites, a new study says.

The wild pig, Sus scrofa, was first introduced to the U.S. from Europe as livestock in the 1500s, but over the years many animals have escaped captivity.

Today there's an estimated four million wild pigs spread across 39 states, with large populations in California, Texas, and the Southeast, according to the study.

Because they're so hardy and can eat almost anything, feral pigs have been living high on the hog, producing several litters of piglets a year, said study co-authorChris DePerno, an ecologist at North Carolina State University in Raleigh.

Mixed into this group are escaped domestic pigs,Sus scrofa domesticus. (Seepictures of unusual domesticated animals, including a Vietnamese potbellied pig.)

Within two generations out of captivity, domestic pigs usually lose their pink hue and turn striped and coarse-haired, DePerno said, allowing them to blend in with feral populations.

Though"Tasty,"Wild Pork May Be Dangerous

In the new research, DePerno and colleagues found evidence of exposure to the parasitesToxoplasma gondiiandTrichinellain the blood of 83 wild pigs killed inNorth Carolinabetween 2007 and 2009.

The results are very similar to those of studies conducted in other parts of the country—including Texas and South Carolina—that show feral pigs could be disease vectors, DePerno said.

(See"Wild Pigs in U.S. Spreading Disease, Ruining Property, Experts Say.")

However, this is the first time scientists have found these particular parasite species in wild pigs, he said.

AlthoughT. gondiiandTrichinellahave been eliminated in domestic swine, more people these days are hunting wild pigs for food, DePerno said.

"They're pretty tasty—more flavorful than domestic pigs."

People would most likely be infected by eating parasite-ridden meat. Once transmitted, both parasitic species can invade muscle tissue and organs and cause flulike symptoms, DePerno said.

More than 60 million men, women, and children in the U.S. already carry theToxoplasmaparasite, but very few show symptoms, because a healthy immune system usually keeps the disease in check.

(Related:"Parasite 'Brainwashes' Rats Into Craving Cat Urine, Study Finds.")

Still, toxoplasmosis—the disease caused byT. gondii—is a leading cause of death due to foodborne illness in the United States, according to theU.S. Centers for Disease Control and Prevention (CDC). The organism is especially toxic to pregnant women and those with weak immune systems.

Trichinellainfections can also range from mild to severe, with the worst cases causing potentially fatal heart and breathing problems, according to the CDC. Even in moderate cases, fatigue, weakness, and diarrhea can last for months.

Education, More Data to Combat Pig-Borne Illnesses

As the feral pig population expands, so will the incidence of wild-pig hunts, the study authors surmise.

The team therefore recommends education programs for hunters, to help them understand the risks of exposure to parasites both from cleaning pig carcasses and eating wild pork.

There's also the possibility that people could get the parasites from regular pork if domestic swine come into contact with infected feral pigs.

For instance, free-range pigs may bump into their wild brethren and pick up diseases—a possible downside to the popularity of free-range pork, he said. (Also see"Swine Flu Virus Hiding Out in Pigs, May Reemerge.")

"The take-home message," DePerno said,"is that more places need to do this kind of research to determine disease prevalence, especially related to domestic pigs, pets, and human health."

The parasite-carrying pigs study appeared in April in theJournal of Wildlife Diseases.

National Geographic News

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Is Your Brain Sleeping While You're Awake?

If you think you can function on minimal sleep, here's a wake-up call: Parts of yourbrainmay doze off even if you're totally awake, according to a new study in rats.

Scientists observed the electrical activity of brains in rats forced to stay up longer than usual. Problem-solving brain regions fell into a kind of"local sleep"—a condition likely in sleep-deprived humans too, the study authors say.

Surprisingly, when sections of the rats' brains entered these sleeplike states,"you couldn't tell that {the rats} are in any way in a different state of wakefulness,"said study co-authorGiulio Tononi, a neuroscientist at the University of Wisconsin, Madison.

Despite these periods of local sleep, overall brain activity—and the rats’ behaviors—suggested the animals were fully awake.

This phenomenon of local sleep is"not just an interesting observation of unknown significance,"Tononi said. It"actually affects behavior—you make a mistake."

For example, when the scientists had the rats perform a challenging task—using their paws to reach sugar pellets—the sleep-deprived animals had trouble completing it.

(See"Secrets of Sleeping Soundly Uncovered.")

Sleep Allows Neurons to Reset?

Tononi and colleagues recorded the electrical activity of lab rats via electroencephalogram (EEG) sensors connected to the rodents' heads.
As predicted, when the rats were awake, their neurons—nerve cells that collect and transmit signals in the brain—fired frequently and irregularly.

When the animals slept, their neurons fired less often, usually in a regular up-and-down pattern that manifests on the EEG as a"slow wave."Called non-rapid eye movement, this sleep stage accounts for about 80 percent of all sleep in both rats and people.

The researchers used toys to distract the rats into staying awake for a few hours—normally"rats take lots of siestas,"Tononi noted.

The team discovered that neurons in two sections of these overtired rats' cerebral cortexes entered a slow-wave stage that is essentially sleep.

Why Do We Sleep?

It's unknown why parts of an awake brain nod off, though it may have something to do with why mammals sleep—still an open question, said Tononi, whose study appears tomorrow in the journalNature.(Read aboutmysteries of why we sleep inNational Geographicmagazine.)

According to one leading theory, since neurons are constantly"recording"new information, at some point the neurons need to"turn off"in order to reset themselves and prepare to learn again.

"If this hypothesis is correct, that means that at some point {if you're putting off sleep} you're beginning to overwhelm your neurons—you are reaching the limit of how much input they can get."

(See"Sleep Cherry-picks Memories, Boosts Cleverness.")

So the neurons"take the rest, even if they shouldn't"—and there's a price to pay in terms of making"stupid"errors, he said.

(Seebrain pictures.)

Even"Alert"People Make Mistakes

Sleep deprivation may have dangerous consequences, Tononi said—and those mistakes may become more common.

For one, many people are getting fewer z's. In 2008 about 29 percent of U.S. adults reported sleeping fewer than seven hours per night, and 50 to 70 million had chronic sleep and wakefulness disorders, according to theU.S. Centers for Disease Control and Prevention. Adults generally need about seven to nine hours of sleep a day,according to the National Sleep Foundation.

(TakeNational Geographicmagazine's sleep quiz.)

What's more, you don't need to feel sleepy to screw up, Tononi emphasized.

"Even if you may feel that you're fit and fine and are holding up well,"he said,"some parts of your brain may not {be} ... and those are the ones that make judgments and decisions."

National Geographic News

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Pictures: Fire Ant Swarms Form Living Life Rafts

When a city floods, humans stack sandbags and raise levees. When a fire ant colony floods, the ants link up to form a literal life raft, such as the one pictured. Now, new research shows exactly how the ants manage this feat.

Engineering professor David Hu and graduate student Nathan J. Mlot atGeorgia Institute of Technologyhad heard reports of ant rafts in the wild that last for weeks. (Watch a fire ant video.)

"They'll gather up all the eggs in the colony and will make their way up through the underground network of tunnels, and when the flood waters rise above the ground, they'll link up together in these massive rafts,"Mlot said. Together with Georgia Tech systems-engineering professor Craig Tovey, the scientists collected fire ants and dunked clumps of them in water to see what would happen.

In less than two minutes the ants had linked"hands"to form a floating structure that kept all the insects safe. Even the ants down below can survive this way, thanks to tiny hairs on the ants' bodies that trap a thin layer of air.

"Even when they're on the bottom of the raft, they never technically become submerged,"Mlot said.

The fire ant life raft research is described in the April 25 issue of the Proceedings of the National Academy of Sciences.

—Rachel Kaufman

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Odd Animal Deaths, Deformities Linked to Gulf Oil Spill?

On the first anniversary of theGulf oil spill, scientists are observing strange deaths and deformities in animals that could be related to the disaster, experts say.

In the past six months, the numbers of dolphin and sea turtle deaths in theGulf of Mexico (map)have risen, and some fish that inhabit the Gulf'scoral reefshave developed abnormalities. (Read more about the Gulf oil spill anniversary.)

Yet projects to document and measure the oil's effects on Gulf marine life are still in the very early stages, scientists caution. Preliminary results may not be available for months, and it may be several years before any kind of scientific consensus is reached.

(See an interactive of the Gulf's layers of life inNational Geographicmagazine.)

Such uncertainty is not unusual for oil-spill studies, notedWilliam Patterson, a marine biologist at the University of West Florida (UWF) in Pensacola.

"If you look at the literature surrounding theExxon Valdezoil spill {in 1989}, there are still some unknowns associated with that,"Patterson said.

"What we know {in the case ofExxon Valdez} is that there was an insult to the system, that there were effects on the food web and ecosystem, and that some species have not recovered to the levels they were at before."(Related:"Exxon ValdezAnniversary: 20 Years Later, Oil Remains.")

Some of theExxon Valdezoil's effects are circumstantial evidence, he added,"but it's pretty compelling evidence."

Mysterious Spike in Dolphin, Turtle Deaths

This winter, an alarmingly high number ofbottlenose dolphins—113 at last count—washed up dead on U.S. shores, according to theNational Oceanic and Atmospheric Administration (NOAA). The agency confirmed in early April that six of the bodies hadDeepwater Horizonoil on them.

(Read more:"Dolphin-Baby Die-Off in Gulf Puzzles Scientists.")

"What's important to note, however, is that even though they have this oil on them, it may not be the cause of death,"Blair Mase, NOAA's marine-mammal investigations coordinator, told reporters at a news briefing April 7.

"That's something the investigative team and our working groups are looking into."

So far this year scientists have also seen a rise in deaths of various species of Gulf sea turtle hatchlings. But NOAA researchers say the culprits may be contact with boats and fishing gear and possibly poisoning by toxins in algal blooms, which naturally appear in the Gulf each spring.

"The carcasses that we have looked at . . . had no visible oil on them,"said Barbara Schroeder, national sea turtle coordinator for NOAA.

(Relatedpictures:"Baby Gulf Turtles Released Into Atlantic.")

Fish Found With Deformed Ovaries, Missing Fins

Meanwhile, other researchers are looking for effects of the oil on other marine species, such asfish, crustaceans, andcorals.

UWF's Patterson has recently observed an increase in physical abnormalities consistent with oil exposure in red snappers that live in Gulf coral reefs.

"There are parasites showing up on the fish. They're always present, but this fall and winter we're seeing them in what appears to be higher abundances,"Patterson said.

Some of the fish are suffering so severely from a disease called fin rot that entire fins are missing—something Patterson said he has never seen before. Some female red snappers also have been discovered with hardened or deformed ovaries.

(Also see"Sex-Changing Chemicals Can Wipe Out Fish, Study Shows.")

Other red snappers have strange pigmentation issues, Patterson said."We have some images of red snappers sent to us by commercial fishermen that have black bands across the sides of the fish that is discolored skin."

These symptoms are not unusual in themselves, Patterson said, but the fact that they're appearing at what looks to be increased rates at the same time concerns him.

"Some of these things that we're seeing are classic symptoms of hydrocarbon exposure that have been documented in lab studies."

For example, the odd pigmentation could be caused by the fish's kidney or bile duct being affected or clogged by oil components.

"So it does seem to be pointing in one direction, but we don't have anything definitive yet to tell the full story."

Chuck Jagoe, an environmental toxicologist at Florida A&M University in Tallahassee, is working with Patterson to test Gulf red snappers for telltale enzymes that are produced when the fish flush toxic oil components from their bodies.

"These enzymes are associated with the detoxification process,"Jagoe said.

"They can give us an indication that the animal has not only been exposed to {oil} compounds, but that the compound is having some kind of biological effect."

Jagoe has just begun testing the fish, and the first results won't be available until at least early summer.

One Species Not Enough Evidence

UWF's Patterson said he also plans to investigate whether other Gulf species are exhibiting symptoms similar to those of the snappers.

Even nearly a year after the disaster, oil could still be lurking in the Gulf's waters, he added.

"Oil is not one thing,"Patterson said."It's thousands of organic compounds. Some of them are fairly {unstable} and microbes break them down very quickly, while others could persist for a long time."

(See"Why the Gulf Oil Spill Isn't Going Away.")

Finding other affected species will be crucial to making a case that the oil spill is having a systemic effect on Gulf fish species, saidProsanta Chakrabarty, a fish biologist at Louisiana State University in Baton Rouge who was not involved in the snapper project.

"With one species, we can't really tell,"Chakrabarty said.

He also noted that red snappers are already a vulnerable species due tooverfishing, and that it's possible the symptoms that Patterson is seeing are due to inbreeding caused by a decreased population.

Whatever the cause of the deformities, though,"the oil spill didn't help any,"he said.

Fish Populations Measured via GPS

Chakrabarty is involved in another project calledDepthmap, which aims to use fish-population data collected using GPS technology before and after the spill to investigate the Gulf oil spill's impact on marine life. Museum records are also used to fill out pre-spill data.

"If, for example, 80 percent of Gulf pancake batfishes were found off the coast of Louisiana and they're not there anymore,"then that could be an indication the spill negatively affected the species, he said.

(See"Two New 'Walking' Batfish Species Found.")

And if this pattern is repeated for many fish species, it would indicate the spill has had a pervasive impact on Gulf marine life.

Chakrabarty's team hopes to gather pre- and post-spill population data for 600 fish species in the northern Gulf, but has only begun analysis for a fraction of that number due to limited funding.

His early results suggest that of the 53 species examined so far, 43 had major populations that lived in regions that were in the path of the spill.

Deep-Sea Effects Leave Scientists in the Dark

Even if Depthmap's goals were met, however, scientists would still know only about the impact the spill had on fish that live in relatively shallow water. But the spill's largest potential damage is to deep-sea creatures, Chakrabarty said. (See pictures of deep-sea animals.)

The broken wellhead blew at 5,000 feet (1,500 meters) underwater, and plumes of gushing oil floated nearly 1 mile (1.6 kilometers) up from the seafloor, polluting different layers of water as they rose.

"We knew that the oil wouldn't last at the surface for very long, but what happened at the deep sea?"Chakrabarty said.

Of particular concern, he added, are the effects of the oil dispersants piped into the waters near the wellhead in a desperate bid to break apart the oil before it reached the surface.

"The deep sea is such a stable environment. . . . It isn't used to perturbations like this influx of {dispersants},"Chakrabarty said.

"So what the impact {is} of having {dispersants} enter that area, even momentarily, is difficult to understand."

(See"Gulf Spill Dispersants Surprisingly Long-lasting.")

Despite his concerns about the deformed fish, UWF's Patterson added that it's important for scientists not to jump to conclusions.

"As scientists, we shouldn't be unwilling to say we're not quite sure,"he said.

"Instead of going out on a limb and making grand announcements, I think it's a safer approach to say, Well, these are issues that we're seeing that we're not able to attribute to any one thing, but we're concerned about them.

"And that's where we are."

*The photographer, a commercial fisher in the Gulf, requested to remain anonymous.

forNational Geographic News

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Gulf Spill Photos: 9 Animal Victims—Plus 2 Survivors

Abottlenose dolphinbreaks the oily surface ofChandeleur Sound, Louisiana (see map), on May 6, 2010, two weeks after an explosion at theDeepwater Horizonoil rig sent crude gushing into the Gulf of Mexico.

Oil, gas, and chemical dispersants contaminated thousands of square miles of marine and coastal habitat. Many animals were killed or sickened outright, but on the one-year anniversary of theGulf oil spill, scientists still don't know the extent of the spill's effects on most species.

(See:"Gulf Oil Spill Pictures: Ten Animals at Risk {May 2010.}")

Bottlenose dolphins have been dying in unusually high numbers in northern Gulf waterssince February 2010, two months before the oil spill began, and the trend continues today. Since January, 68 premature, stillborn, or newborn calves have washed ashore.

The Gulf oil spill is certainly on the list of suspects in the recent dolphin deaths, but it's too early to say for sure, Blair Mase, coordinator of the Southeast Marine Mammal Stranding Network of theNational Atmospheric and Oceanic Administration, told National Geographic News in March.

Only a handful of obviously oiled dolphins have been recovered. But a recent study from theUniversity of British Columbiaestimated that the actual number of dolphins and whales killed by the spill could be 50 times higher than official tallies suggest, putting the death toll in the thousands.

—Rebecca Kessler

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Migrating Birds Escaped Worst of Gulf Oil Spill

A year aftertheGulf oil spill, predictions of massbirddie-offs and disrupted migrations have not come true—but oil is still oozing into some bird habitats, experts say.

The timing of the disaster had especially worried scientists and bird-watchers, since it came amid the annual spring migration of tens of millions of birds through the Gulf of Mexico.

(Watchvideo:"Gulf Spill Still Threatens Millions of Migrating Birds.")

"There is still the potential for impacts, but nothing like last year,"said Michael Carloss of theLouisiana Department of Wildlife& Fisheries.

Carloss, who directed the agency's rescue response, hasn't seen any"obvious"changes in migratory patterns or the numbers of birds arriving or passing throughLouisiana—a major bird habitat.

But he describes the damage assessment to wildlife as a"long, arduous process."

(Get more Gulf oil spill anniversary news.)

Breeding Birds May Get Oiled

In the short term, birds in Louisiana may still get oiled by tar balls that are still washing up on beaches and oozing in marsh grasses.

(Read more about Louisiana's embattled wetlands inNational Geographicmagazine.)

Melanie Driscoll, Gulf Coast director of bird conservation for the National Audubon Society, said she's"incredibly dismayed"that oil remains in areas where birds nest and feed in the ongoing breeding season.

Birds can get oil on their feathers and transfer it to eggs or hatchlings, which are especially vulnerable to the oil's toxicity.

With cleanup efforts still under way, the simple act of trying to repair the damage from the oil can actually do more harm.

The small shorebird Wilson's plover is especially susceptible to disruptions, Driscoll said. Cleanup crews have fenced off roads through the grasses that often lie between the birds' nests and their main food sources. Though the birds can squeeze through the fencing, it adds more stress to a bird population that's been declining for decades. (Seevideo:"Citizen 'Scientists' Track Birds in BP-Spill Zone.")

Audubon scientists have also found marine worms burrowing into tar balls in Grand Terre, Louisiana. Lab tests found concentrations of toxic hydrocarbons in the tar balls that could enter the food chain and pose long-term health risks to adult birds or harm developing bird embryos.

Habitat Loss Could Push Birds Over the Edge?

Possibly the most worrying legacy of the spill is the acceleration of habitat loss, scientists say.

For example, some Louisiana bays were hit with heavy oil last summer. The marsh grass that holds the marsh together is dying in many areas—which means that storms, waves, and ship wakes will simply wash away more of the wetlands.

(Seepictures:"Heavy Oil Seeping Into Louisiana Marshes {May 2010}.")

Wildlife& Fisheries' Carloss said it will be difficult to tease out how much habitat loss can be attributed to the spill or the long-standing yearly loss of wetlands from erosion and subsidence. But he says the combination of oiling and cleanup operations in critical marsh habitat clearly must have some effect.

For instance, inLouisiana's Barataria Bay (see map), submerged mats of oily material still send oil ashore nearly every day into many bird species' nesting habitats, Audubon's Driscoll said. (See waterbird pictures.)

For birds flying thousands of miles from wintering spots in the south to nesting sites as far as the Arctic, any loss of shelter, food, and fresh water could leave them too weak to make the journey or diminish their reproductive success when they reach nesting sites.

"A lot of these birds live right on the edge, with an incredibly physically demanding journey,” said David Ringer, Audubon's communications coordinator for the Mississippi River and Gulf of Mexico.

"Anything that goes wrong on the way can push them over the edge."

forNational Geographic News

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Pictures: 20 Surprising Species of the Past 20 Years

Back for an encore after a round of Web stardom as"Yoda bat"last fall,Papua New Guinea's tube-nosed fruit bat has now been named one of the top20 new or rarely seen species encountered during the first 20 years of Conservation International's Rapid Assessment Program(RAP), which launched in 1990.

(Readmore about the tube-nosed fruit bat.)

The RAP expeditions typically send large teams of scientists into remote habitats for intense, monthlong surveys.

"We go out and explore so that we can bring a wide range of new species—1,300 so far—and thousands of other rare and really interesting species to the public and policy makers,"explained RAP director
Leeanne Alonso.

"Showing people what's there helps us make the best decisions about how to manage areas to keep these species around, while continuing the benefits that humans get from these places."

In other words: Help us, they will.

—Brian Handwerk

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Eyes Made of Rock Really Can See, Study Says

When it comes to hard stares and stony gazes, no animal can match the chiton, a small mollusk with eyes made of rock crystal. Now a new study shows just what these strange eyes are capable of.

Scientists had long known that chitons have hundreds of beadlike structures resembling eyes on the backs of their shells. The lenses"are like big, clear pieces of rock,"said study leaderDan Speiser, a marine biologist at the University of California, Santa Barbara. (Related:"Coral Algae Have 'Eyes,' Study Says.")

What's been unclear, however, is if the creatures could actually see using these organs or whether the eyes were good only for sensing changes in light intensity.

"It's been known for over a hundred years that these eyes exist, but no one's really tested what sort of vision they provide,"Speiser said.

His latest research—conducted while he was a graduate student at Duke University in North Carolina—revealed that the sea creatures' eyes are the first known to be made of the mineral aragonite, the same material chitons use to make their shells.

What's more, these stony eyes likely have unique advantages over the squishy eyeballs of other animals.

(Related:"Eyeless Urchins 'See' With Spines.")

Mollusks in Lockdown

To test the chiton's vision, Speiser and his team collected Indian fuzzy chitons(Acanthopleura granulate)from the Caribbean.

When left alone, a chiton will lift part of its oval-shaped body to breathe. But when threatened, the animal will clamp down tightly on the seafloor to protect its soft underbelly.

In the lab, the scientists placed individual animals on a stone slab beneath a white screen, which could change colors. Once the chitons seemed relaxed, the team either placed a black disk directly above the mollusks or changed the color of the background screen from white to gray.

The black disk was designed to simulate a suddenly appearing predator, while the dimming screen mimicked subtle changes in natural light that chitons might experience in the wild—for example, when a cloud passes in front of the sun.

In the experiment, the chitons went into lockdown mode when shown the black disk, but the animals remained at ease when the screen dimmed. This suggests the chiton's eyes are able to distinguish shapes, a prerequisite for true vision.

"The eyes allow the chitons to see objects—not with much detail—but they can distinguish between approaching objects and just decreases in light,"Speiser said.

Speiser estimates chiton vision is about a thousand times courser than human vision, and it's likely they see only in black-and-white. (Related:"Sharks Are Color-Blind, Retina Study Suggests.")

"Even compared to other animals with small eyes, chitons don't see particularly well,"Speiser said.

Rock Eyes Better for Tidal Creatures

Chitons' rock eyes do appear to have some specific advantages. For one thing, the hard aragonite is extremely resilient, an important trait for chitons, which are constantly being pummeled by waves in their natural habitats, shallow tidal pools.

"If their eyes were made of protein"—which is the case for humans and most other animals—"they would get worn right away,"Speiser said. (See"Hammerhead Sharks Have 'Human' Vision.")

For another thing, the experiments suggest aragonite allows the chitons to see equally well in air or underwater, something that's probably useful as tides ebb around the mollusks.

"Behaviorally, the chitons react the same"in both mediums, Speiser said.

That's probably because aragonite has two refractive indices, the extent to which a particular material focuses incoming light. With an aragonite eye, one index creates an image on the eye in water while the other works in air.

Meanwhile, a few mysteries remain about chiton eyes. For instance, it's still not known why only some chiton species have eyes, or how the creatures are able to use the same material to make both their eyes and their shells.

"It's going to be interesting to see how they're shaping these lenses,” Speiser said."How do they make them the right size and shape and keep them translucent? They're exerting some very fine control."

The chiton-eyes research will be detailed in the April 26 issue of the journalCurrent Biology.

forNational Geographic News

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New"Buck-Toothed Evil Spirit" Dinosaur Found

A newly discovered dinosaur species bridges the gap between the earliest known group of predators and more advanced beasts such asTyrannosaurus rex,according to a new study.

Found atNew Mexico's Ghost Ranch fossil site, the primitive dinosaur lived about 205 million years ago. (Relatedpictures:"'Nasty' Little Predator From Dinosaur Dawn Found.")

The dinosaur, which stood as tall as a large dog, boasts a very unusual skull, said study co-authorHans-Dieter Sues, a vertebrate paleontologist at the National Museum of Natural History in Washington, D.C.

"It has a deep, short snout and these monstrous front teeth. That's a kind of skull structure for a predatory dinosaur that's really unexpected for this early point in time,"Sues said.

These features helped earn the new dinosaur the nameDaemonosaurus chauliodus,or"buck-toothed evil spirit"in Greek.

(Also see"'Weird' Buck-toothed Dino Found in China.")

Earliest Dinosaurs Were Survivors

The oldest known dinosaurs lived in what's now South America during the lateTriassic Period, some 230 million years ago. This group included early versions of two-legged predators known as theropods.

But a big gap in the fossil record just after this time led many experts to suggest that these early dinosaurs had simply died out.

"The idea,"Sues said,"was that there was this early diversification of dinosaurs ... but then they went extinct, and more advanced predators took over during the late Triassic and diversified later at the Triassic-Jurassic boundary, when we know that dinosaur predators greatly diversified and increased a lot in size."

Now theDaemonosaurusfind links the two dinosaur groups.

"Our new dinosaur, along with another one that was found a few years ago ... at the same site, indicates that those basal dinosaurs already included a number of early theropods, and that they survived all the way through the Triassic to nearly the beginning of theJurassic Period."

(Seepictures:"New T. Rex Cousin Suggests Dinosaurs Arose in South America.")

Bucktooth Dino Bridges Evolutionary Gap

For nowDaemonosaurusis known only by its fossilized skull and neck vertebrae.

But the fossils show that the dinosaur has several features—including cavities in its vertebrae linked to the respiratory system—that bridge the evolutionary gap between the earliest dinosaurs and the neotheropods, the next group of predatory dinosaurs to evolve.

Finding the dino in New Mexico adds another interesting aspect to the discovery, Sues said.

"We had some inkling that the earliest dinosaurs had made it into the Northern Hemisphere when the supercontinent Pangaea was still in existence and animals could walk around on dry land. But the fossil record was limited to South America,"he said.

"The new find gives further evidence that the earliest radiation of dinosaurs did have a wider distribution, and it is due to the incompleteness of the fossil record that we'd found them only in Argentina and Brazil."

The new dinosaur is described in the April 13 issue of the journalProceedings of the Royal Society B.

forNational Geographic News

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Penguin Numbers Plummeting—Whales Partly to Blame?

Penguin populations have plunged by as much as 50 percent during the past three decades in the West Antarctic Peninsula and Scotia Sea, scientists report.

The problem appears to be a shortage ofkrill, the seabirds' primary fare, caused by rising regional air temperatures and rebounding populations of hungry whales.

Fisheries biologistWayne Z. Trivelpieceof the National Marine Fisheries Service in La Jolla, California, has been monitoring colonies of chinstrap andAdélie penguinssince the mid-1970s.

Because Trivelpiece regularly bands and monitors individual penguins, he's been able to uncover a key factor in the collapse: Far fewer young penguins are surviving their first winter on their own, because they're having a hard time finding krill.

"It's gone from about half of the chicks surviving in the 1970s and mid-1980s to only about one tenth now,"Trivelpiece said.

"And we see from direct measurements of krill that there's about 80 percent less out here than there was just 20 years ago. So the probability of young penguins finding it often enough to survive during those first months of independence is much reduced."

(See"Adélie Penguins Extinct in a Decade in Some Areas?")

Penguins at Risk as Krill Vanish

Krill are tiny, shrimplike animals that live in enormous numbers and represent a large part of the Antarctic food web. Like flocks of herbivores on land, krill feed on single-celled plants called phytoplankton and are in turn gobbled up by many marine predators, including penguins.

The local krill collapse is probably due to a pair of factors, Trivelpiece said.

One is regional air temperatures, which are some 10 degrees Fahrenheit (5 or 6 degrees Celsius) higher than they were in the 1940s and 1950s. Those temperatures drive how much ice forms at the sea surface.

"If the ice no longer forms, phytoplankton in that sea ice aren't available to provide a winter food source for the young krill that spawned the summer before,"Trivelpiece said."Without that food, the young krill don't survive."

(Related:"'Crazy Green' Algae Pools Seen in Antarctic Sea.")

The second krill killer is actually a conservation success story—rebounding populations of whales.

"From what information is available, stocks of krill-eating whales are beginning to return, and their numbers are growing,"Trivelpiece said. (Related:"Whale Hunting to Continue in Antarctic Sanctuary.")

Nineteenth- and 20th-century whale hunts, which severely impacted populations of the giant marine mammals, appear to have ushered in a penguin heyday.

"We don't have good data prior to the 1930s, but it appears that at least the 1930s to the 1970s were a real boom time for penguins, primarily because of the removal of competition in the form of whales."

"Population data from that period is largely anecdotal and provided by the rough counts of British Antarctic workers. But even if you're counting by the seat of your pants, the difference between 100,000 penguins in the 1930s and 500,000 or 600,000 in the 1970s is enormous."

Marine ornithologist Steve Emslie also provided valuable evidence of the boom with his studies of historic penguin colonies. Chemical analyses of old tissue sources, such as eggshells, found that Adélie penguins actually had been fish-eaters before whale numbers dropped.

"Only in the last hundred years or so did krill come into their diet, when the whales were taken out of the system and there was a krill surplus,"Trivelpiece said.

(See"Penguins Changed Diet Due to Whaling, Study Suggests.")

Can Penguins Survive Without Krill?

With krill now dwindling, the previous shift in penguin behavior begs a question: Can the birds simply switch back to eating fish?

"From everything we've seen over a 30-year period, while krill has declined 80 percent, we haven't seen an increase of fish in {penguin} diets,"Trivelpiece said.

"But the fish stocks have also been heavily fished out by Russian trawlers, so we don't even know how much of that prey is available to them at this point."

The penguin-decline study appears in this week's issue of theProceedings of the National Academy of Sciences.

forNational Geographic News

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