OKINAWAN
OPISTHOBRANCH OF THE WEEK

Dolabella auricularia (Lightfoot, 1786) 115mm

Opisthobranch of the Week Data

Taxonomy:

Frequency on Okinawa:
Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]


Species Account:

        Dolabella auricularia is one of a group of herbivorous opisthobranchs, commonly referred to as "sea hares". The common term "sea hare" is derived from the rabbit-like appearance of the group, the rhinophores of course suggest the long ears of rabbits. Although D. auricularia is considered to be very common at Onna Flats on Okinawa, I've collected only the above featured single specimen of these large anapsids. They're commonly seen on low spring tide "night reef walks" here. This is certainly one of the largest species of sea hares found in the Indo-Pacific and Gosliner, et. al. (1996) report that it may reach one-half meter in length.

        D. auricularia is immediately recognized by the flattened disk on the posterior surface of the animal. The species is frequently found with its body covered with a series of soft pustules, giving the animal a rather distinctive knob-like appearance (the above featured animal is obviously without these "knobs", but rather with an abundance of frilly extensions which are seen here).

        The animal gives off copious amounts of a purple ink when disturbed and this ink is sometimes the only clue to its daytime presence, at which time it is frequently found buried beneath the surface of the sand. If the animal is inadvertently stepped upon while traversing a silty-sand covered tidal pool, the purple ink strongly suggests the presence of one of the Okinawan sea hares (Aplysia dactylomela, another large anapsid, behaves the same and is also found on Okinawa in the same habitat).

        I've added an additional page with several images of both the animals and their mantle-imbedded shell.

Literature Cited:


Page Date: 14 May '01
Page Modification Date: 15 May '01
Digitally manipulated photo
Copyright © 2001 Robert F. Bolland