Related to hermit crabs and resembling lobsters, there are over 850 species of squat lobsters. One of them, Munidopsis andamanica, has been recently discovered to eat wood! Scavengers by nature, squat lobsters have made wood debris their primary food source as other food supplies dwindle.
Researchers at the University of Liège in Belgium studied squat lobsters off the coast of Vanuatu. By raising sunken logs from the Pacific Ocean floor, they found the waterlogged wood covered in “bivalves, limpets, and crustaceans”. They even found wood fragments in the squat lobster’s digestive systems. Natural History Magazine explains:
If that seems an improbable diet for a deep-sea crustacean, consider that most logs that wash out to sea eventually sink, delivering precious nutrients to the seafloor in irregular loads that biologists have lately recognized as important ecosystems…
M. andamanica found elsewhere had bits of plant matter, algae, and coral in their guts. The team thinks the crustaceans specialize in hard-to-digest food, wood being their favorite fodder, garnished with bacteria or fungi. In a habitat as barren as the deep sea, it seems no meal is too tough to pass up.
Published in Marine Biology, scientists hypothesize bacteria helps the Munidopsis andamanica digest the wood. As reported by the BBC, University of Liège PhD candidate Caroline Hoyoux describes the discovery:
We were surprised, because crustaceans are often regarded as predators or scavengers. The fact I found M. andamanica consistently feeding on vegetal remains, especially wood, instead of eating molluscs or [worms] breaks with the general a priori about the diet of squat lobsters.
The wood falls that we study are principally natural tree debris that have sunk and reached the deep sea floor. They consist of real wood as well as plant fragments like leaves, seagrass, coconuts etc.
Munidopsis andamanica was first discovered in 1905 by A.C. MacGilchrist, but it was only recently their diet of wood was revealed.