Basking sharks, manta rays, whale sharks, and baleen whales all have one thing in common: their eating habits. These animals are marine filter feeders. They get their meals by straining tiny organisms from the seas in which they swim. Basking sharks, manta rays, and whale sharks employ gill rakers to sift their food from the water. Baleen whales filter food from water using, as their name implies, a keratinous structure known as baleen.

The tradition of filter feeding is not new. There is evidence of marine vertebrates that used this feeding strategy during the Middle Jurassic. The largest fish that ever lived, Leedsichthys, was a filter feeder that measured a whopping 9 meters in length. Until now, scientists believed that Leedsichthys was one of only a few filter feeders that lived for a short time during the Jurassic. But now, a new report reveals fossil evidence for an entire dynasty of big filter feeding fish that spanned a much longer period of time than previously thought.

Image courtesy of Robert Nicholls / www.paleocreations.com.

Giant Filter Feeders of the Jurassic originally appeared on About.com Animals / Wildlife on Tuesday, March 9th, 2010 at 17:33:08.

Permalink | Comment | Email this

When compared to brown bears, polar bears are the new species on the block. The two species diverged from each other 150,000 years ago on islands in the Alexandar Archipelago, Southeast Alaska.

A study published in the Proceedings of the National Academy of Sciences details the research that led to this conclusion. Scientists from Penn State University, the University at Buffalo, the University of Oslo collaborated to analyze a rare pair of fossil —a jawbone and tooth from an ancient polar bear.

The fossils—the tooth and jawbone—were discovered in 2004 by an Icelandic geologist working in Norway's Svalbard archipelago. The find was unique—few polar bear fossils have been discovered and are believed to be rare. "Because polar bears live on the ice, their dead remains fall to the bottom of the ocean or get scavenged. They don't get deposited in the sediments like other mammals," said Oystein Wiig, a co-author of the study from the University of Oslo's Natural History Museum.

Photo courtesy US FWS.

Ancient Jawbone Hints at Polar Bear Origins originally appeared on About.com Animals / Wildlife on Wednesday, March 3rd, 2010 at 21:30:19.

Permalink | Comment | Email this

A sea turtle begins its life as an egg buried beneath a pile of sand at the edge of the sea. After hatching, a sea turtle must dig its way out of the nest to reach the surface. Once at the surface the tiny turtle is exposed and vulnerable to predators. It must find its way—quickly—over clumps of dune grass, loose sand, and wet beach to reach the relative safety of the ocean where it will spend the rest of its life.

Sea turtles have four flippler-like limbs that are specially adapted for life in water. They enable the turtles to maneuver and propel themselves through the open ocean. But the turtles' flippers are adapted for more than just swimming. It turns out they also are well suited for crawling through sand and turf, a skill so much needed during those first moments of a sea turtle's life when it has to crawl from the nest to the ocean.

Scientists from the Georgia Institute of Technology conducted a field study to show just how sea turtle hatchlings use their limbs to move quickly across the varied surfaces—loose sand, packed sand, vegetation—to get to the ocean.

"On hard-packed sand at the water's edge, these turtles push forward by digging a claw on their flipper into the ground so that they don't slip, and on loose sand they advance by pushing off against a solid region of sand that forms behind their flippers," said Daniel Goldman, assisatnat professor at the Georgia Institute of Technology School of Physics.

The information Daniel Goldman and team gathered may help robotics engineers to build robots that are better able to cross similar terrain.

Photo © Alan Rees / Georgia Tech.

Sea Turtle Hatchlings Are Sure-Footed on Sand originally appeared on About.com Animals / Wildlife on Monday, March 1st, 2010 at 10:06:09.

Permalink | Comment | Email this

Polar bears are no longer the only bear to roam Canada's Wapusk National Park. According to Robert F. Rockwell and Linda Gormezano from the American Museum of Natural History and City University of New York, grizzly bears have recently moved into the region.

Wapusk National Park lies in the northeastern stretches of Manitoba on the shores of the Hudson Bay. The region was once thought to be too isolated for grizzlies to migrate to. But in 2008, Robert F. Rockwell and Linda Gormezano spotted a grizzly bear while flying over the region surveying fox dens. That sighting inspired them to examine records and trapping data for the region to find out how common grizzly sightings had been over recent years.

They discovered that prior to 1996, no grizzly sightings had been recorded, but between 1996 and 2008, there were nine confirmed sightings. In the summer of 2009, three sightings were recorded.

"The opportunistic sightings seem to be increasing," Linda Gormezano said. "This is worrying for the polar bears because grizzly bears would likely hibernate in polar bear maternity denning habitat. They would come out of hibernation at the same time and can kill polar cubs."

Scientists are still uncertain whether the grizzlies are settling in the region or just wandering through. To this point, no grizzly dens or cubs have been spotted to indicate that they are settling permanently in the region.

Photo © Linda Gormezano / City University of New York.

Grizzly Bears Wander into Polar Bear Habitat originally appeared on About.com Animals / Wildlife on Wednesday, February 24th, 2010 at 10:04:44.

Permalink | Comment | Email this

Photos: Top 25 Most Endangered Primates originally appeared on About.com Animals / Wildlife on Tuesday, February 23rd, 2010 at 10:09:58.

Permalink | Comment | Email this

This collection of images shows leaf-cutter ants clipping and carting away chunks of leaves and tending their subterranean fungus gardens.

Photos: Leaf-Cutter Ants Tend Their Garden originally appeared on About.com Animals / Wildlife on Tuesday, February 16th, 2010 at 00:26:15.

Permalink | Comment | Email this

Leaf-cutter ants are crafty cultivators. They tend vast gardens of fungus that they harvest to feed their minions. In return, the ants care for the fungus. They constantly clip and compost bits of leaves to form a rich substrate on which the fungus thrives. When the fungus is attacked by pathogens, the ants fight back, armed with bacteria that counteract the pathogen.

The fungus gardens the ants tend are complex communities. There are numerous interactions in the gardens, both symbiotic and parasitic. Scientists are just now starting to unravel the many complex connections that exist in an ant fungus garden. The latest discovery, made by Adrian Pinto-Tomas and colleagues, reveals that the fungal gardens tended by leaf-cutter ants are a haven for one of life's most basic processes: nitrogen fixation.

Read more...

Leaf-Cutter Ants Dabble with Nitrogen Fixation originally appeared on About.com Animals / Wildlife on Monday, February 15th, 2010 at 23:59:23.

Permalink | Comment | Email this

Insects - Class Insecta originally appeared on About.com Animals / Wildlife on Wednesday, February 10th, 2010 at 22:26:41.

Permalink | Comment | Email this

Ernst Haeckel's Artforms of Nature originally appeared on About.com Animals / Wildlife on Wednesday, February 3rd, 2010 at 23:10:55.

Permalink | Comment | Email this

Who is Ernst Haeckel? originally appeared on About.com Animals / Wildlife on Wednesday, February 3rd, 2010 at 23:09:30.

Permalink | Comment | Email this