Remipedia is a class of Crustaceans first described by a fossil member, Enantiopoda (Lower Pennsylvanian). Since 1979, about a dozen living species have been encountered in the Caribbean and Australia. All living members are eyeless and live in deep caves connected to salt sea water. These species have been assigned to one order Nectiopoda and two families Godzilliidae and Speleonidae.

Members of this group are colorless with a head and up to thirty-two similar body segments composing an elongate trunk. The swimming appendages are lateral on each segment, and these animals swim on their backs. They are generally slow moving, and use fangs and poisonous glands to kill their prey. They have a generally primitive body plan in crustacean terms, and have been thought to be a basal, ancestral crustacean group. However Fanenbruck et al (2004) showed that at least one species, Godzilliognomus frondosus, has a highly organised and well differentiated brain, with a particularly large olfactory area (not surprising in a species that lives essentially without light). The size and complexity of the brain suggested to Fanenbruck et al that the Remipedia might be a sister taxon to the Malacostraca, regarded as the most advanced of the crustaceans.

References

• Fanenbruck, M., Harzsch, S., & Wägele, J. W. (2004). The brain of the Remipedia (Crustacea) and an alternative hypothesis on their phylogenetic relationships. Proceedings of the National Academy of Science. Published online 5th March 2004.