Bizarre New Species of Crab Lives Entirely in Trees

A crab that lives in trees. Peter K.L. Ng et al/Oxford University Press

Crabs that live in trees? It's official: Mother Nature has thought of everything.

What's truly surprising is that such a bizarre and unique creature has somehow escaped detection by scientists until now. The new species, which was discovered in the forests of the Western Ghats in south India, was recently described in the Journal of Crustacean Biology. It was found thanks to help from the local Kani tribe, who knew of the crab's existence long before scientists did. The crab was named Kani maranjandu in their honor.

This isn't the first crab known to spend time in trees; there are tree crabs in other parts of the world, including within India. But it's the first "true arboreal crab" ever found, since it appears to live its entire life in the trees, never returning to a body of water found outside of the trees. The crab still needs water, of course, but it relies entirely on pools of water found within the hollows of its tree home.

Part of the reason these crabs have evaded scientific discovery for so long is that they're extremely shy. Kani tribespeople had to teach researchers how to locate the animals by looking for debris and air bubbles pushed out from their tree holes. Aside from tree-living, the new species is also distinguishable due to its dark black-purple shell and its diagnostic elongated walking legs, specialized for arboreal life.

Scientists believe the discovery to be especially important because the crabs serve as ecological indicators. As tree crab populations fare, so too fares the forest ecosystem where they live.

"As water holding hollows in large trees are essential for the survival of this unique species, the discovery also stresses the need for conservation of large trees in the degraded forest ecosystems of the Western Ghats," explained Dr. Biju Kumar, one of the study's authors, to "It also highlights how little we know about the actual biodiversity that resides in these forests and the efforts that must still be made to find and study the many undoubted new species that still live there."