Onchidella nigricans is a species of small, air-breathing sea slug, a shell-less marine pulmonate gastropod mollusc in the family Onchidiidae.
This species occurs in New Zealand, as well as on the coast of south-eastern Australia, where it is common.[1]
O. nigricans is a general herbivore feeding on algae. It also consumes zooplankton.
This species can be found in the intertidal zone on a variety of habitats.