Opisthobranch of the Week Data
Ceratosoma gracillimum is considered to be very rare on Okinawa as I have seen and collected only a single individual. The above featured animal was found and collected beneath the pier from a vertical concrete support piling; the animal was found approximately a meter and a half from a silty-sand bottom, covered with strewn oyster shell rubble. The piling from which the animal was collected was covered with a large array of miscellaneous free-standing and encrusting invertebrates (bryozoans, cnidarians, pelecypods, poriferans), as well as relatively large numbers of urochordates. The Ceratosoma most apt to be confused with C. gracillimum is C. trilobatum, however, C. trilobatum has an obvious mantle rim between the head and lateral body extensions.
Ceratosoma gracillimum has a tropical Indo-Pacific distribution.
As of this writing (April, 2001) C. gracillimum is one of
seven species of Ceratosoma known from Okinawa. The seven species identified to date