Black-margined Nudibranch
Doriprismatica atromarginata
Cratena Slug
Cratena peregrina
About
The Cratena slug is a slender white nudibranch, a shell-less sea slug, dressed in tufts of bright colour that look almost too vivid to be real.
Also known as: feathered sea slug, wandering cratena
How to tell it apart
Many nudibranchs carry colourful cerata, but this one's bright orange rhinophores stand out clearly against its plain white body and head.
Appearance
The body is thin and milky white, tapering to a sharp point at the tail. Along the back sit 8 to 10 clusters of finger-like cerata, gill-like outgrowths in red, purple, brown, or blue, each tipped with a glowing blue. The head carries a pair of bright orange rhinophores, its sensing horns, plus two long whitish tentacles near the mouth.
Diet
It feeds on the hydroid Eudendrium racemosum, a small colonial animal that looks like a fuzzy plant. It targets polyps that have just caught plankton, so it swallows both the polyp and the stolen meal inside it. Plankton eaten this way makes up at least half of its diet, while the hydroid itself is only a small part.
Did you know?
Its feeding style, eating both the hydroid and the plankton already trapped inside it, is a mix of hunting and theft that scientists had to coin a new word for: kleptopredation.
Log it in Into the Blue
Describe what you saw and we name it, then keep every species you find in your Oceandex.
