Phyllodesmium crypticum
Rudman, 1981

Family: Glaucidae


Known from tropical eastern Australia, but possibly more widely spread in the western Pacific.


UPPER: Phyllodesmium crypticum Angourie, northern New South Wales, Australia. October 1979. Length 5cm. PHOTO: Bill Rudman.
LOWER: Section through a tentacle of the soft coral Xenia showing the pouches of symbiotic zooxanthellae (stained red). Xenia is the preferred food of Phyllodesmium crypticum.
PHOTO: Bill Rudman.


Solar-powered Sea Slugs

As its name suggests, Phyllodesmium crypticum is a very cryptic species, well-camouflaged amongst the colonies of the soft-coral Xenia in which it lives and on which it feeds. This is another of the many species of aeolid which store zooxanthellae from their food, presumably obtaining nourishment when they photosynthesise. The large sacs of zooxanthellae found in the tentacles of Xenia are clearly the source of Phyllodesmium's zooxanthellae.

This species is very similar in appearance to Phyllodesmium hyalinum, another species found in association with the soft coral Xenia. See Phyllodesmium hyalinum, for distinguishing features of the two species.

• 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.

Authorship details
Rudman, W.B., 1998 (October 11) Phyllodesmium crypticum Rudman, 1981. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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