The gorgeous, glowing sea slug Phyllodesmium acanthorhinum looks like the gastopod version of a neon sign. Described in the journal The Veliger, this slug was discovered off the coast of Japan and grows to only about an inch (17 mm to 28 mm) in length. This new species, which photographs in shades of blue, red and gold, also contributed to a better understanding of the origin of an unusual symbiosis in other species of the genus. 

Related sea slugs have multibranched guts in which algae called zooanthellae live. These algae have a primary symbiotic relationship with the corals on which the sea slugs feed.

The Phyllodesmium acanthorhinum made it to the top 10 NEW SPECIES:  For this sea slug, the Top 10 competition was more than a beauty contest. It is a ‘missing link’ between sea slugs that feed on hydroids and those specializing on corals. Gastropods do not get more photogenic than sea slugs whose graceful lines and vivid coloration make them beauties of the deep. This new species, which photographs in shades of blue, red and gold, also contributed to a better understanding of the origin of an unusual symbiosis in other species of the genus. Related sea slugs have multi-branched guts in which algae called zooanthellae live. These algae have a primary symbiotic relationship with the corals on which the sea slugs feed. Once sequestered in the gut, the photosynthetic algae produce nutrients of benefit to the host. The newly identified species is an inch long, more or less (17-28 mm), and resides in the Japanese islands.

Kingdom: Animalia
Phylum:  Mollusca
Class: Gastropoda
Family: Facelinidae
Size:  17-28 mm
Etymology: The name refers to the spiny appearance of papillae on the surface of the rhinophores or paired smelling organs at front end of body.
Type locality:  Japan, Ryukyu Islands, Okinawa, near Onna Village, Horseshoe Cliffs
Holotype:  California Academy of Sciences, San Francisco
More information: Moore, Elizabeth and Terrence Gosliner. 2014.  Additions to the genus Phyllodesmium, with a phylogenetic analysis and its implications to the evolution of symbiosis. The Veliger 51: 237-251. photo: Robert Bolland source: www.esf.edu >>