Opisthobranch of the Week Data
Crosslandia viridis, a dendronotinian nudibranch, is more similar appearing to the sacoglossans (Elysia spp.) than to the group of nudibranchs to which it belongs. The large wing-like parapodia and the forward projecting rhinophore stalks and related pockets make this a unique appearing animal. The species is apparently quite variable in color and the Sea Slug Forum features animals ranging from bright green to dark brown, from Eastern Australia (Heron Island & New South Wales), Southern Australia, and Tanzania. The following information concerning the species is taken from Bill Rudman's Sea Slug Forum (Rudman, 1999):
The rhinophores are hidden in small pockets at the tip of the tentacle-like extensions to the front edge of the mantle. Crosslandia is closely related to Notobryon and Scyllaea, the latter adapted for life on floating pieces of brown algae. All members of the family feed on hydroids living on algae. Only one species is recognised from the Indo-West Pacific and it ranges from bright green to dull brown, apparently matching the algae or seagrass it is living on.
I've not personally seen nor collected any specimens and it is unknown from Okinawa Island at the current time (early August, 2001), but it has been photographed by Atsushi Ono in the Kerama Islands. The close proximity of the main island of Okinawa to the Kerama Islands, as well as the similar opisthofauna to that of the Kerama Islands, suggests the possibility that it is also present here on Okinawa proper. The above featured animal is one which was photographed from a small bay in the waters of Zamami Island, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa capitol, Naha. This featured animal was photographed by Atsushi Ono in March of 2000, from the waters of Zamami Island, from a small bay in 5m of water. The animal was found on the chain of a buoy. Atsushi's photograph is used here with his kind permission and the species is considered to be very rare in the Kerama Islands (Ono, via per. comm., reports seeing only the single individual featured above).