Phyllodesmium serratum
(Baba, 1949)

Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Glaucidae

DISTRIBUTION

Known from Japan and all states of Australia. Probably has wide tropical western Pacific distribution.

PHOTO

UPPER, LOWER LEFT: Tasman Peninsula, southern Tasmania, Australia, February 1984, 35mm long.
LOWER LEFT: Feeding on colony of stoloniferan octocoral Clavularia sp.
LOWER RIGHT: Feeding on gorgonian Junceela sp., Darwin, Northern Territory, Australia, November 1986, 14mm long.
PHOTOS: Bill Rudman.

Many species of Phyllodesmium, such as Phyllodesmium longicirrum, have evolved a symbiotic relationship with single-celled plants called zooxanthellae which they keep alive in their bodies, and living to some extent from the porducts of the zooxanthellae photosynthesis. These "solar-powered" nudibranchs are described elsewhere in the Forum. Phyllodesmium serratum does not have such a relationship, and is unusual in feeding on a wide variety of octocorals. In Tasmania and Victoria it feeds on the stoloniferan Clavularia sp and in New South Wales it is often found on the telestacean Carijoa sp.. The white animal figured here from the Darwin was one of a whole cluster of juveniles found feeding on the gorgonian Junceela sp. Interestingly they are the offspring of an animal which was collected feeding on the alcyonacean Steronephthya. As colour is dependent on the colour of the food they are eating, this species is highly variable in colour except for the white median dorsal line.

• Rudman, W.B. (1981) The anatomy and biology of alcyonarian feeding aeolid opisthobranch molluscs and their development of symbiosis with zooxanthellae. Zoological Journal of the Linnean Society, 72: 219-262.
• Rudman, W.B. (1991) Further studies on the taxonomy and biology of the octocoral-feeding genus Phyllodesmium Ehrenberg, 1831 (Nudibranchia: Aeolidoidea). Journal of Molluscan Studies, 57(2): 167-203.

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