Neuroanatomy of a hydrothermal vent shrimp provides insights into the evolution of crustacean integrative brain centers

Alvinocaridid shrimps are emblematic representatives of the deep hydrothermal vent
fauna at the Mid-Atlantic Ridge. They are adapted to a mostly aphotic habitat with extreme
physicochemical conditions in the vicinity of the hydrothermal fluid emissions. Here, we
investigated the brain architecture of the vent shrimp Rimicaris exoculata to understand possible
adaptations of its nervous system to the hydrothermal sensory landscape. Its brain is modified from
the crustacean brain ground pattern by featuring relatively small visual and olfactory neuropils that
contrast with well-developed higher integrative centers, the hemiellipsoid bodies. We propose that
these structures in vent shrimps may fulfill functions in addition to higher order sensory processing
and suggest a role in place memory. Our study promotes vent shrimps as fascinating models to
gain insights into sensory adaptations to peculiar environmental conditions, and the evolutionary
transformation of specific brain areas in Crustacea.