A shell-less marine mollusk of the order "Nudibranchia"; a sea slug.
- ‘Equally well represented in these waters are invertebrates such as crinoids, nudibranchs and featherduster worms.’
- ‘There were dense walls of soft corals, sponges, anemones and hydroids, nudibranchs, creepy-crawlies and lots of fish.’
- ‘While the adult nudibranch is correctly identified, the veliger larva is not a nudibranch.’
- ‘While Antarctic sponges are indeed subject to little, if any, fish predation, they are heavily preyed on by sea stars and nudibranchs.’
- ‘The nudibranch Melibe leonina swims by rhythmically flexing its body from side to side at a frequency of I cycle every 2-5 sec.’