Opisthobranch of the Week Data
Aldisa sp. 1 is considered to be very rare on Okinawa as I have seen and collected only the single above featured individual. The animal was collected during a mid-morning SCUBA excursion from an area primarily composed of open sand with occasional pockets of coral rubble. Several handfuls of sand and rubble ("grunge sample") were scooped up by hand and placed into a zip-loc bag; later at home Aldisa sp. 1 was found crawling about in a sorting pan.
Species of Aldisa tend to be very good at camouflaging themselves to resemble sponges. Some individuals have several mid-line dorsal pits which mimic the excurrent pores (oscula) of some colonial sponges. The orange color of Aldisa sp. 1 is very similar to that of A. pikokai (photographed and collected by Atsushi Ono in the Keramas *), but that species has three dorsal pits while Aldisa sp. 1 has but two dorsal pits.
As of the current date there are two described species of Aldisa known from Okinawan waters. These two are:
A. albatrossae A. pikokai (from the Kerama Islands)
In addition to these described species I've collected quite a few unknown specimens of Aldisa which may be made up of several separate species.
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.
Page Date: 08 Dec '03
Page Modification Date: 08 Dec '03
Digitally manipulated photo
Copyright © 2003 Robert F. Bolland