Wild Things: Life as We Know It

Scientists suspected that the common thresher shark used its long tail to capture food—and now they have video to prove it. Researchers working off the coast of Southern California with an underwater camera recorded 29 shark strikes. In the 19 successful strikes, a shark swung the upper part of its caudal fin to hit and stun a fish, immobilizing its prey before digging in to eat.

Hermit crabs that have outgrown their snail shells synchronize their search for new housing. Researchers in Belize report when one crab finds an empty shell, it waits until a crowd forms, then the crabs “piggyback,” or climb onto one another’s shells, in a line from largest to smallest. Once one crab shimmies into the free shell, the others follow, like dominoes.

Aye-ayes, a kind of lemur, have long, skinny fingers that seize grubs squirming beneath tree bark. How do they protect their delicate digits, particularly when climbing down trees headfirst? By shifting weight to their palms and curling their fingers away from the tree, says Tracy Kivell of Germany’s Max Planck Institute for Evolutionary Anthropology. “It’s the reverse of knuckle-walking.”

Cobras raise their heads when threatened and spread their hoods. To trace the patterns of muscle activation that allow this distinctive and startling behavior, scientists at the University of Massachusetts and elsewhere inserted electrodes into cobra muscles. High-speed video then documented that one set of muscles lifts the hood; a second keeps the skin taut; and a third aligns the hood’s ribs.

Name: The field cricket Teleogryllus oceanicus.
Some Sing Males attract females by rubbing their forewings together to chirp. Males who can’t or don’t “sing” lurk near singers to mate with lured females.
Who Listens? Females do, for sure—but so do juvenile males, note biologists at the University of California at Riverside.
What Happens? Males who grow up amid lots of singers tend to have bigger testes than those who don’t. They’re in better physical condition and more likely to sing. The study shows that insects’ behavior and bodies are keenly attuned to their social environments.