After the discovery of the Yeti Crab (Kiwa hirsute), scientist at the University of Southampton began to wonder if there were other species in the newly discover genus Kiwa. However, many ecologist, including some of the discovers of the first Yeti Crab, doubted other species existed, and believed that Kiwa was just a single species genus.
After expeditions to many underwater trenches across the world (From Antarctica to Costa Rica), two new species of the crab have been discovered, thus adding to the former cryptid list.
"We knew immediately that we'd found something tremendously novel and unique in hydrothermal vent research," says study leader Sven Thatje, an ecologist at the U.K.'s University of Southampton.
Analysis of the Antarctic crabs revealed that they were genetically distinct species, according to the new study.
Waters near East Scotia Ridge are generally just above freezing. However, the liquid spewing out of the vents themselves is superhot, and can exceed 700 degrees Fahrenheit (about 400 degrees Celsius).
Because the water cools rapidly away from the vents, K. tyleri has only a tiny, Goldilocks-like space in which it can survive. Too close to the vent and they fry. Too far away and they freeze.
As a result, Thatje says the Antarctic yetis cluster together much more closely than the other two known species. He observed them on top of one another, "like beans in a jar, filling every available space"—some 700 specimens per 11 square feet (a square meter).
Thatje also said the newfound species is better built for climbing than its kin—since it has shorter and more robust front limbs. K. tyleri is also more stout and compact than its abyssal plain-loving cousins. This physique likely allows the crustacean to jockey for position on vents' vertical surfaces.
The team also saw some females outside the vent's habitable zone. Thatje hypothesizes that like many other deep-sea species, yeti crab larvae require colder temperatures to develop.
Which means mom has to make a big sacrifice: The cold takes a visible toll on the females, deteriorating their bodies over time. Female crabs likely breed only once before death.
Overall, yeti crabs are excellent at adapting to their harsh lifestyles. Since there's no sunlight where these crabs live, they've evolved another way to obtain energy: They "farm" their own food.
The crabs have hair-like structures on their chest and arms, called setae, that attracts bacteria, their main diet.
These hairy chests have inspired its nickname of "Hoff crab," in homage to David Hasselhoff of Baywatch fame.
No offense to Hasselhoff, but Thatje says he prefers the official species name, K. tyleri, which he and his team chose to honor the lifetime achievements of Paul Tyler, a emeritus professor of the University of Southampton and a pioneer in deep-sea research.
Andrew Thurber, an ocean ecologist at Oregon State University, says the Antarctic yeti crab is "a really amazing discovery."
That's especially true because no one knew these animals existed a decade ago, says Thurber, who helped describe the second-known species of yeti crab, which lives off the coast of Costa Rica, in 2011.
"It just identifies how little we still know," he says, "and how some of these new species may be much more widespread than we thought."