Phyllodesmium magnum

Order : NUDIBRANCHIA
Suborder : DEXIARCHIA
Infraorder : CLADOBRANCHIA
Parvorder : AEOLIDIDA
Superfamily : AEOLIDIOIDEA
Family : Facelinidae

DISTRIBUTION
Known from tropical Western Pacific, and Western Australia. Records on the Forum show a widespread Indo-West Pacific distribution.

This is one of the larger species of Phyllodesmium, and from the branched arrangement of the digestive gland, flattened cerata, and position of zooxanthellae in the sunlit parts of the skin, it is most probably one of the species which retains zooxanthellae alive in its tissue so that it can benefit from their photosynthetic activity. See Solar-powered Sea Slugs for further detail.

All species of Phyllodesmium, feed on octocorals, and the defensive cnidosac found in other aeolids is absent. However, they have evolved an alternative defensive strategy. When attacked or disturbed their cerata can be cast off voluntarily, much like a lizard drops its tail. The autotomised cerata produce a sticky epithelial secretion and wriggle around vigorously for a considerable length of time after dropping off, apparently causing sufficient distraction to deter further interest in the now even more naked nudibranch.

This species probably feeds on, and obtains its zooxanthellae, from the soft coral Sinularia.