Stichopus horrens is a benthic shallow water, tropical reef species and can be found in the inner lagoon, or reef flat hidden under boulders during the day (Conand, 1993a). S. horrens is active at night, coming out from shelter to feed. It uses mutable connective tissue (Ruppert et al., 2004) to wedge hard into crevices under rocks (Kropp, 1982). S. horrens is found in densities of approximately 50 per hectare (Conand, 1993a), with an almost equal ratio of males to females (Conand, 1993b). S. horrens is not found deeper than 25m, and is always situated close to the coast (Conand, 1993a). Larger individuals seem to be found in deeper waters, possibly suggesting a migration to deeper water with age (Conand, 1993a). Most individuals orient toward the current, those that do not orient in this direction seem to be behind a boulder or an obstacle that slows the current (Kropp, 1982). S. horrens is in the order Aspidochirotida, which has been recorded recorded to have a symbiotic relationship with a small fish (Carapus) which lives in it’s anus (Nichols, 1967). The fish is said to shelter in the anus and comes out at night to feed on crustaceans. It is unknown whether S. horrens does actually have this symbiotic relationship. Scambicornus modestus is a copepod that is an internal parasite (endoparasite) of S. horrens (Paulay, 2012). While this parasite is common in S. horrens around the world it is unknown whether it is found in Australia. It is common in many sea cucumber species (Paulay, 2012).