Black-margined Nudibranch
Doriprismatica atromarginata
Geometric Goniobranchus
Goniobranchus geometricus
About
A tiny, jewel-toned sea slug that grazes quietly on sponges along the reef, easy to miss unless you know exactly what colour to look for.
- Depth
- up to 23 m
How to tell it apart
This species looks almost identical to another nudibranch, Goniobranchus conchyliatus. The two are easy to tell apart by colour alone: this species has green-grey gills and rhinophores, while its look-alike has red ones.
Appearance
This is a small nudibranch, a shell-less sea slug, with a soft mantle covering its back. Its ground colour ranges from creamy brown to purple, and the mantle is covered in small cream-coloured bumps with a plain white edge running all the way around. On its head it carries a pair of feathery gills and rhinophores, the small sensory tentacles nudibranchs use to smell and taste the water; on this species both are white to greenish.
Did you know?
It feeds on a specific sponge, Chelonaplysilla violacea.
Log it in Into the Blue
Describe what you saw and we name it, then keep every species you find in your Oceandex.
