Comparative Study of Chemosensory Organs of Shrimp From Hydrothermal Vent and Coastal Environments

<p>The detection of chemical signals is involved in a variety of crustacean behaviors, such as social<br />
interactions, search and evaluation of food and navigation in the environment. At hydrothermal<br />
vents, endemic shrimp may use the chemical signature of vent fluids to locate active edifices,<br />
however little is known on their sensory perception in these remote deep-sea habitats. Here,<br />
we present the first comparative description of the sensilla on the antennules and antennae<br />
of 4 hydrothermal vent shrimp (<em>Rimicaris exoculata</em>, <em>Mirocaris fortunata</em>, <em>Chorocaris chacei</em>,<br />
and <em>Alvinocaris markensis</em>) and of a closely related coastal shrimp (<em>Palaemon elegans</em>). These<br />
observations revealed no specific adaptation regarding the size or number of aesthetascs<br />
(specialized unimodal olfactory sensilla) between hydrothermal and coastal species. We also<br />
identified partial sequences of the ionotropic receptor IR25a, a co-receptor putatively involved in<br />
olfaction, in 3 coastal and 4 hydrothermal shrimp species, and showed that it is mainly expressed<br />
in the lateral flagella of the antennules that bear the unimodal chemosensilla aesthetascs.</p>