Comprehensive Description

Jorunna funebris (Mollusca: Gastropoda: Opisthobranchia: Nudibranchia: Kentrodoridiae)

Dotted nudibranchs are classified in the Opisthobranchia subclass. Opisthobranchs have undergone major evolutionary radiation in connection with habitat and diet, but none are parasitic (Rudman and Willan 1998). Opisthobranch molluscs are known to possess a great variety of chemicals. Most of them are associated with specific ecological function including defence, inter- and intraspecific communication (Fontata et al. 2001)

Within Opisthobranchia, J. funebris resides in the Dorididae suborder. Dorididae is largest nudibranch suborder, with a wide variety of morphological types. An easily recognisable synapomorhy for all dorid nudibranchs is that their respiratory organ, gills, encircle the anus on posterior dorsum. The gills are also retractable and can contract into a protective pocuch (Todd 1983).

Dotted nudibranchs are easily identified by their distinctive white mantle, with brown spicules arranged in ovoidal patterns, which vary between individuals. The spicules are crysalyine needles, and provide another layer of protection from predation (Garcia-Gomez et al. 1990, Cimino et al. 1999). Spicules also help J. funebris become completely cryptic against thier usual habitat of coral clumps. J. funebris are selelparous, have an annual lifecycle, and veliger larvae (Todd 1983).

Dotted nudibranchs only feed on sponges. Some know recordings of sponges eaten by J. funebris include Xestospongia sp., Haliclona sp., Euplacella cf. australis, and Oceanapia sp (Fontana et al. 2000, Charupant et al. 2007).

Because nudibranchs have secondarily lost their hard shell, other methods of protection have evolved. J. funebris has the spicules for protection, but also use chemical defence. This chemical defence is in the form of secondary metabolites (Charupant et al. 2007). Secondary metabolites are derived from undigested remains of organisms that were fed on by J. funebris. The undigested remains are sequested and accumulated, and then can be used to biosynthesise secondary metabolites (Cimino et al. 1999, Fontana et al. 2001).  The main metabolite produced in dotted nudibranchs is jorumycin, and because jormycin can be found in the mucus, it suggests that it plays a defensive role for dotted nudibranchs (Fontana et al. 2000).