In the 1980s, scientists identified a crab species in the Philippines and gave it the delightful of name of Insulamon unicorn. Twenty years later, scientists have found some of its cousins (pdf): four new freshwater crab species in the same genus. This purple one with red-tipped claws is I. palawanese.
Isolated on the island, the Insulamon have evolved to live in freshwater rather than seawater, hiding out under roots and rocks near stream beds. This little guy is remarkably colorful and easy to spot, despite being less than two inches across.
[via Discovery News]
Considering the huge numbers of species that have had their DNA sequenced in the wake of the genomics revolution, it might be surprising that scientists are so excited about a tiny freshwater crustacean. But this one is special: The genome of the water flea contains a staggering 30,907 genes—the most ever seen in an animal, and about 8,000 more than humans have.
Daphnia has a large number of never-before seen genes…. “More than one-third of Daphnia‘s genes are undocumented in any other organism — in other words, they are completely new to science,” said Don Gilbert, coauthor and Department of Biology scientist at IU Bloomington. [Discovery News]
According John Colbourne, coauthor of the study in Science, those never-before-seen genes are not dead weight, but rather some of the most important in the crustacean’s genome for responding to changes in its environment.
Not all of the crustacean’s genes are active at any given time. Rather, a large portion of them are switched on or off with changes in the flea’s environment. They are “more or less environment-specific,” Colbourne says. Although they are “coding for the same proteins, they’re being expressed differently depending on what environmental stresses you expose the animal to.” [Scientific American]
There’s a lot more going on beneath those huge sheets of Antarctic ice than you might think. NASA researchers say they uncovered a major surprise in December: The team drilled an eight-inch hole and stuck a video camera 600 feet down, hoping to observe the underbelly of the thick ice sheet. To their amazement, a curious critter swam into view and clung to the video camera’s cable [Washington Post]. The three-inch crustacean in their video (and pictured in the image here) is a Lyssianasid amphipod, a relative of a shrimp. The team also retrieved what they believe to be a tentacle from a jellyfish.
“We were operating on the presumption that nothing’s there,” said NASA ice scientist Robert Bindschadler, who will be presenting the initial findings and a video at an American Geophysical Union meeting Wednesday. “It was a shrimp you’d enjoy having on your plate” [AP]. Indeed, researchers previously believed that nothing more complex than microbes could live in such a hostile place, beneath an ice sheet in total darkness. While complex organisms have shown up before in retreating glaciers, this seems to be the first time any have been found 600 feet down below an intact sheet of ice.
In a bit of unexpected climate related good news—not for us, of course—some shell-building ocean dwellers like blue crabs, shrimp, and lobsters may actually benefit from increased ocean acidification. This surprising finding seems to be good news for lobster lovers, but researchers note that the ongoing acidification still appears to spell trouble for many marine creatures.
Scientists now think that acidifying oceans may allow these select crustaceans to build stronger shells and exoskeletons, instead of making them more brittle. Carbon dioxide (CO2)—the notorious byproduct of fossil fuel burning—dissolves in the ocean. That makes the ocean more acidic. It also reduces the number of so-called carbonate ions in seawater, and these ions are among the primary materials that sea creatures use to build their calcium carbonate shells and skeletons [LiveScience]. Justin Ries, a coauthor on the new study, speculates that these bottom dwellers are somehow better able to manipulate CO2 ions to build their shells, even though fewer CO2 ions are available to them in an acidic environment. However, exactly how they accomplish this is unknown.
Crabs and other crustaceans not only feel pain, new research has found, but they remember it—and use the experience to try to avoid future shock. For the study, published in Animal Behavior, researchers Robert Elwood and Mirjam Appel looked at how hermit crabs reacted to small electric shocks. Using wires, they delivered the shocks to the abdomens of the hermits who take shelter inside other mollusks’ abandoned shells, and found the crabs would scamper out of the shells after being shocked, “indicating that the experience is unpleasant for them,” the scientists concluded; unshocked crabs stayed put [LiveScience]. The researchers say their study proves that this response is not just a reflex, but that central neuronal processing takes place [CNN].
The role of pain, according to Elwood, is to allow an individual to be “aware of the potential tissue damage” while experiencing “a huge negative emotion or motivation that it learns to avoid that situation in the future” [Discovery News]. Prior research had shown that crabs can detect and withdraw from harmful stimuli, but it was not certain whether that was a simple reflex mechanism, disassociated from the feeling humans recognize as pain.