
Black-margined Nudibranch
Doriprismatica atromarginata
Tambja morosa

The gloomy nudibranch is a small sea slug with a dark body and bright blue marks. It grows up to 7 cm long. Its wrinkled skin looks almost black underwater, which fits its gloomy name.
Body colour can be black or dark green, depending on where you dive, so do not rely on that alone. Check instead for the row of about five round blue spots on the back. This spot pattern stays the same even when the base colour changes.
This nudibranch is normally black, though some are dark green in cooler waters. Its skin is wrinkled. It has about five round blue spots along its back, a blue band around its head, and a bright blue edge along the margin of its body.
Describe what you saw and we name it, then keep every species you find in your Oceandex.