This species has only been found around the South African coast from Saldanha Bay to Port Alfred, intertidally to at least 30 m.[2] It is endemic to South Africa.

Cratena capensis grows to between 10 and 30 mm in total length.

It is a slender pale-bodied nudibranch which has smooth white rhinophores and a pair of elongated oral tentacles.

The head bears two 'eye' patches of orange or red.

Its egg mass is a broad coil of one or two whorls.