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