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acid glands

egg mass

Gymnodoris okinawae
Baba, 1936
Gymnodoris okinawae
Maximum size:  30 mm (Kay, 1979).

Identification:  This species has a cream body decorated with orange spots and white patches. In younger animals, the white patches appear more extensive with better defined margins. In older animals the orange spots often fuse into short lines and meandering, subcutaneous acid glands may develop. The gills form a complete ring around the anus and often have opaque white pigment at their bases. Young animals can be distinguished from Gymnodoris sp. #6 by their more uniformly distributed white pigment and lack of rod-like rhinophores.

Natural history:  Gymnodoris okinawae is a common species found in protected to exposed rocky habitats at depths of < 1 to 3 m (< 3 to 10 ft). Kay (1979) states that it feeds on the genus Elysia. We've recorded it feeding on Elysia in holding dishes but we've also recorded it feeding on Thuridilla and Colpodaspis suggesting a somewhat broader diet. (Note 1) It lays a bright orange egg mass that hatches in about 7 days in the laboratory.

Distribution:  Big Island, Maui, Lanai, Oahu, French Frigate Shoals and Midway: widely distributed in the Indo-Pacific.

Taxonomic notes:  This species was first reported from Hawaii in Kay & Young, 1969. There's some chance that the yellowish animals treated as juveniles might turn out to be different.

Photo:  CP: 16 mm: Hekili Point, Maui; Oct. 27, 2004.

Observations and comments:

Note 1:  In August, 2002 a G. okinawae was left overnight in a holding dish with an Elysia pusilla, a Thuridilla carlsoni and a Colpodaspis thompsoni. In the morning, all three had disappeared and the Gymnodoris was very "fat."
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