|The diet of the Harlequin crab Lissocarcinus orbicularis, an obligate symbiont of sea cucumbers (holothuroids) belonging to the genera Thelenota, Bohadschia and Holothuria|Caulier, G.; Lepoint, G.; Van Nedervelde, F.; Eeckhaut, I. (2014). The diet of the Harlequin crab Lissocarcinus orbicularis, an obligate symbiont of sea cucumbers (holothuroids) belonging to the genera Thelenota, Bohadschia and Holothuria. Symbiosis 62(2): 91-99. dx.doi.org/10.1007/s13199-014-0274-2
In: Symbiosis. Springer: Philadelphia, Pa.. ISSN 0334-5114, more
Bohadschia Jaeger, 1833 [WoRMS]; Gastrolepidia clavigera Schmarda, 1861 [WoRMS]; Holothuria Linnaeus, 1767 [WoRMS]; Lissocarcinus orbicularis Dana, 1852 [WoRMS]; Thelenota Brandt, 1835 [WoRMS]; Marine
Symbiotic crab; Crab diet; Holothuroid; Harlequin crab; Stable isotopes
The present paper characterizes, for the first time, the diet of the Harlequin crab Lissocarcinus orbicularis, an obligate symbiotic crab that associates with sea cucumbers (holothuroids) belonging to the genera Thelenota, Bohadschia and Holothuria. These tropical holothuroids host a rich symbiotic community in the Indo-West Pacific Ocean of which the Harlequin crab is the best known. The diet of L. orbicularis was characterized by analyzing the microscopic, molecular and isotopic signatures obtained from its gastric content. The presence of sea cucumber ossicles in the gastric mills of the crabs suggests that symbionts eat the superficial integument of their host and this was supported by the fact that Holothuroid DNA was detected in the stomach of L. orbicularis after DGGE and sequencing of the 18S rDNA gene. The stable isotopic d13C and d15N values of crab tissues were compared with diverse potential food sources including three holothuroids, three algae, one sea grass as well as the organic matter contained in the water column, in the sediment, and the second most abundant symbiont, the polychaete Gastrolepidia clavigera. The low d15N values of crabs suggests that the crabs do not exclusively feed on sea cucumber tissue but assimilate diverse food sources such as sea grasses and organic matter contained in sediment that have similar d13C values. There were no differences between the feeding of males and females but there was a positive correlation between the carapace length and the stable isotopic values indicating a shift of the food source as crabs grow larger.