The symbiotic relationship between Sea cucumbers (Holothuriidae) and Pearlfish (Carapidae)

The relationship between sea cucumbers (Holothuriidae) and pearlfishes (Carapidae) is a relatively unknown system. In this study, we set out to answer questions regarding the nature of this relationship; i.e. parasitic, mutualistic or commensal. The Holothuridae species we studied were Thelenota ananas and Bohadschia argus and the Carapidae species we examined were Encheliophis Boraborensis and Carapus homei. We measured the distribution of holothurians by performing transects at three sites in Moorea, French Polynesia. We collected Holothurian hosts with potential Carapus occupants over a four-week time period. We ran a series of experiments at C.R.I.O.B.E. research station. We observed that host specificity was not significant in this system. However, interspecific and intraspecific competition between the carapidae species was present. Species association of Carapidae with location of Holothuriidae was also prominent. Introduction Holothurians are members of the phylum Echinodermata. These organisms occur throughout the world’s oceans and are usually found in shallow reef areas and in areas of sand and rubble. Most species feed on the organic film that coats the sandy bottom by passing sand through their digestive tract and excreting the unused matter (Allen and Steene,1994). Some species release sticky threads called Cuverian tubules to ward off predators (Gosliner, Behrens and Williams, 1996). In more serious predatory situations, the cucumber may eviscerate its internal organs as an offering to prevent more important tissues from being eaten, and will then later regenerate those organs. The family Holothuriidae serves as a host to several species of pearlfish. The family Carapidae are commonly found living in the body cavities of several invertebrates including asteroids, bivalves and holothurians. These fish are usually found in shallow to moderately deep water. Although not much is known about their larval metamorphosis, they are thought to have two distinct larval stages. The planktonic larval stage is dubbed the vexillifer stage and occurs directly after the hatching of the egg. The larvae then metamorphose into the tenuis stage in which the body lengthens and the animal becomes