Opisthobranch of the Week Data
This relatively large nudibranch is quite remarkable and once seen is difficult to forget. Melibe fimbriata looks like something the American director George Lucas, of Star Trek fame would have chosen for one of his extra-terrestrial species. Gosliner, Behrens, & Williams (1996) report that this bizarre animal attains a size of more than 200mm; although the above featured animal, at 110mm, pales in contrast with animals in excess of 200mm, none the less it's remarkably large for such a seemingly fragile animal.
Gosliner, Behrens, & Williams (1996) also report that Melibe fimbriata is the largest and most wide-spread Indo-Pacific species of Melibe. As of this writing I've found only two confirmed Melibe species on Okinawa: M. fimbriata and M. pilosa; there is also a possibility that I have M. mirifica here as well, but the specimen identification has not yet been confirmed. In addition to the preceding three animals, I've also found a very small undescribed species which is sometimes collected in large numbers from 4.6m or less.
Melibe fimbriata is considered to be very rare on Okinawa as the featured animal is the only one collected as of this date (3 January, 1999). The animal was found amid a large patch of open sand in 8m of water. At the time of collection the visibility was quite reduced and I was in the process of making a compass run across the bottom. With my face close to the substrate I came across an obvious mucus trail and after following it for a minute or so I found the specimen. It was slowly crawling in a straight line with its large paddle-like lateral appendages being displaced back and forth as a result of the unstable surface water conditions. If I hadn't been following the mucus trail, intent on finding what was responsible for it I would have thought the animal to have been a patch of detrital or algal material. The animal had its large oral hood distended which was apparently being used to trap its zooplanktonic prey.