The small, eyeless crustaceans known as Remipedia have been underestimated, scientists say. According to a report published online this week by the Proceedings of the National Academy of Sciences, the creatures actually have highly organized and well differentiated brains. The findings suggest that the animals may belong further up the evolutionary tree, alongside crabs and lobsters.

Discovered in 1979, Remipedia inhabit deep, dark ocean caves and use fangs and poisonous glands to kill their prey. But just how the animals should be classified amongst their fellow crustaceans is the subject of ongoing debate. Martin Fanenbruck of the University of Bochum in Germany and his colleagues reconstructed the brain anatomy (see image) of the remipede Godzilliognomus frondosus. They found that the brain is surprisingly complex, considering G. frondosuss generally slow movements and ancient body plan. The olfactory region in particular is very large, the team reports, because the creatures rely predominantly on smell to locate food in their cavernous surroundings.

The scientists estimate that the number of neurons G. frondosus has is comparable to that of higher-level malacostracans, such as crabs, shrimps and lobsters. Consequently, they argue, Remipedia should be considered a sister group to Malacostraca.