Recognition and use of ascidian hosts, and mate acquisition by the symbiotic pea crab Tunicotheres moseri (Rathbun, 1918): the role of chemical, visual and tactile cues

Abstract

Many crustaceans live in intimate association with larger host animals, mostly for shelter and food. Host recognition and location behaviors by these crustaceans, and other symbionts, are vital in the life history of most symbioses. The pinnotherid crab Tunicotheres moseri (Rathbun, 1918) is a common symbiont with various solitary ascidians throughout its reported range of Jamaica, Venezuela, and West Florida. Sensory cues affecting host recognition, host use, and mate acquisition in the West Florida crab population were the focus of this study. T. moseri responded to host generated and conspecific (males responded to non-gravid females) waterborne chemical cues. Although host generated waterborne chemical cues were recognized by T. moseri, access to direct contact (which could involve chemical, visual and tactile cues) with host ascidians triggered much stronger responses. Results of conditioning trials suggest that T. moseri is a generalist, but prefers Styela plicata even after conditioning with the novel host species Molgula occidentalis and Phallusia nigra. These results show that T. moseri employs the use of multiple senses in establishing symbioses with host tunicates, and the plasticity of the responses allow potentially novel tunicates to serve as hosts. Finally, this study shows that male T. moseri, which typically only enter tunicates for breeding purposes, use waterborne cues to find tunicates housing potential female mates.

Population distribution, host-switching, and chemical sensing in the symbiotic shrimp Lysmata pederseni: implications for its mating system in a changing reef seascape

“…Chemically mediated host attraction has been reported for a few other symbiotic crustaceans (Ambrosio and Brooks 2011;De Bruyn et al 2011;Williamson et al 2012); this attraction might play a role in increasing the chances of finding not only a suitable (host) refuge but also sexual partners in obligate symbiotic crustaceans like L. pederseni. However, our results indicate that a relatively large number of hosts were unoccupied in natural populations (*70-80%), and thus, the ability to detect conspecifics over long distances through chemical cues should pay (in term of fitness) to individual shrimp as it should allow them to locate and remain in close proximity to putative mating partners.…”

Host use pattern of the pea crab Afropinnotheres monodi: potential effects on its reproductive success and geographical expansion

“…for future ovigerous females. Assuming that males are able to distinguish between female stages (Diesel 1988;De Bruyn et al 2009;Ambrosio & Brooks 2011), they could increase their mating opportunities by living near hosts infested with receptive females. Indeed, A. monodi males were found in the 1:1 sex ratio only on the two host species harbouring mainly hard/receptive females (clams and cockles), whereas soft females were found mainly in mussels.…”

Territoriality and Conflict Avoidance Explain Asociality (Solitariness) of the Endosymbiotic Pea Crab Tunicotheres moseri

“…The present study tests the prediction that symbiotic crustaceans inhabiting small and morphologically simple hosts should exhibit territoriality ([ 3 ] and references therein). We used the endosymbiotic pea crab Tunicotheres moseri ( Fig 1 ) and its morphologically simple and small ascidian host Styela plicata ( Fig 1 ) as a model system to test this prediction [ 34 – 35 ]. This monotypic crab is considered to be a commensal symbiont and typically inhabits the atrial chamber of a small number of solitary ascidian species (e.g., S .…”

“…This monotypic crab is considered to be a commensal symbiont and typically inhabits the atrial chamber of a small number of solitary ascidian species (e.g., S . plicata , Phallusia nigra , Molgula occidentalis , and Polycarpa spongiabilis ) in the Caribbean and eastern Gulf of Mexico [ 24 , 34 – 35 and references therein]. The atrial chamber (a subdivision of the already restrictive internal body cavity) of ascidians is a relatively small and structurally simple refuge that likely protects T .…”