Wild Things: Yeti Crabs, Guppies and Ravens

Tree killers and the first beds ever round up this month in wildlife news

raven
Yva Momatiuk & John Eastcott / Minden Pictures

Deep-Sea Harvest

Yeti Crab
(Andrew Thurber / Oregon State University)
A species of Yeti crab (Kiwa puravida) recently discovered at the bottom of the Pacific Ocean may be the world’s deepest farmer. Scientists from the Scripps Institution of Oceanography in La Jolla, California, and elsewhere, diving in the research submarine Alvin, collected the crabs 3,300 feet below the ocean surface off the coast of Costa Rica. The crabs have a specialized whip-like appendage that scrapes the bacterial filaments from their claws and scoops the meal into their mouths. As it happens, these deep-sea bacteria feed on chemicals from seafloor hydrothermal vents, which release plumes of methane and sulfide. The researchers saw the crabs waving their claws rhythmically over the vents: They were apparently fertilizing their crops.

How Ravens Say "Please Come Here"

raven
(Yva Momatiuk & John Eastcott / Minden Pictures)
The corvids—jays, crows and ravens—make tools, cooperate and hide food from potential thieves. Now researchers in the Austrian Alps have observed ravens gesturing. In male-female pairs, one bird picked up a stick or bit of moss and pointed or waggled it. The other then approached. It’s a first for non-apes, the biologists say, evidence that corvids “rival even primates in many social cognitive domains.”

Bedding Down

mattress
(Image courtesy of Marion Bamford)
Early humans knew the importance of a good night’s sleep. Archaeologists led by the University of the Witwatersrand uncovered the oldest-known mattress, in a South African rock shelter. Made of sedges and grasses, the 77,000-year-old bedding held laurel leaves, which emit insect-killing chemicals, like a prehistoric mosquito net.

Tree Killer

aspen trees
(Tim Fitzharris / Minden Pictures)
After a drought in the West several years ago, aspen trees started dying in large numbers. The drought ended, but “sudden aspen decline” continued and now affects 17 percent of Western aspen forests. A Stanford University-led study in 51 Colorado sites found that aspens’ ability to transport water has been impaired, particularly in their roots. Researchers conclude that ongoing thirst is causing die-offs.

Observed: Trinidadian guppy Poecilia reticulata

Trinidadian guppy
(Biosphoto / Michel Gunther)
Chemistry: Females emit pheromones when they are receptive to mating.
Coercion: Male guppies breed ceaselessly, even harassing nonreceptive females.
Camouflage: But females have a way to rebuff unwanted advances, according to a new study: hang out with females that are ready to mate. Receptive females’ pheromones drew males’ attention away from nonreceptive females that wanted none of it. “I would expect that this strategy would be seen in other species,” says Safi Darden of the University of Exeter in Britain, “where females face similar amounts of unwanted sexual attention from males.”