Sagaminopteron nigropunctatum

The general body shape is that of a member of the family Gastropteridae in that it has paired parapodia which extend up over the dorsum, an elongate tapered tail, a posterior funnel on the cephalic shield, an internal shell and a relatively short free mantle margin on the right side.

Description

The basic body color is a transparent grey covered with numerous black punctate markings and light grey to cream coloured pustules. The posterior rim of the funnel, the tip of the cephalic tentacles, the tip of the dorso-median crest and the flagellar appendage are lined in orange. In different specimens varying numbers of other orange specks can be found. Max size is 20 mm.

Distribution

Western Indian ocean to Western Pacific ocean

Habitat

It is always found associated with a species of the sponge Dysidea and compared with other gastropterids, S. nigropunctatum is reported to be rather 'sluggish' seldom seen to swim.

Biology

It feed on the sponge Dysidea granulosa. It sequesters the major BDE in the sponge and accumulate it in the mantle at approximately the same concentration as in the sponge (4.03 and 2.37%, respectively), and concentrate it in their parapodia at over twice the sponge concentration (7.97 and 10.10%, respectively). This metabolite is also transferred to the egg masses of S. nigropunctatum (2.22%) where is may offer protection from bacteria.