Ecology

The tropical spiny rock lobsters inhabit two distinct habitats, rubble and rock dens (Trendall & Bell, 1989). In the shallow and warm waters, lumps of coral or rock form fixed “rock” shelters. Most of the P.ornatus population reside under these permanent shelters of small coral bommies at depths of 5-25m (Pitcher et al, 1992c). In deeper water, crevices among loose coral rubble form ‘rubble dens’ which offer temporary shelter to the lobsters (Trendall & Bell, 1989).

The lobsters typically shelter in their dens during the day and emerge to feed nocturnally, returning to their dens before dawn (Pitcher et al. 1992c). While relatively sedentary, their positions are often revealed to divers due to their conspicuous long antennae that can grow up to 2 feet (61cm). P.ornatus, like other members of Panulirus genus, lack large pinching claws and rely on their long spines covering most of their body as a primary form of defence. They are also notably known for their muscular abdominal tails which can powerfully flick rapidly as an escape and deterrance mechanism (Pitcher et al. 1992c).

Habitation of these dens is often communal with lobsters usually found in groups of two or more (Trendall & Bell, 1989).  P. ornatus has been found to exhibit the least habitat specificity of the Panulirus genus, having been found as deep as 200m and in moderately turbid waters near river mouths and mangroves (Pitcher et al, 1992c).