Great thread!
People use the terms 'sea slug' and 'nudibranch' interchangeably. So it gets confusing. Sea slug is any slug that doesn't have a shell (verses snails). Nudibranchs are sea slugs. But, not all sea slugs are nudibranchs. Nudibranchs are one group (order) of sea slugs.
Nudibranch is pronounced Nudi-brank.
All nudibranchs are carnivores. Therefore, they aren't usually wanted in most aquarist's tanks.
Their are four suborders within the ORDER NUDIBRANCHIA:
- DORIDINA (e.g. dorids).
- Feed on sponges, bryozoans and tunicates.
- DENDRONOTINA
- With few exceptions, dendronotids feed exclusively on cnidarians.
- ARMINA
- Feeds on gorgonians (e.g. sea pens) and soft corals, but the nudibranchs in this category tend to be found breaking the rules often and can be found feeding on a variety of critters.
- AEOLIDINA (e.g. Montipora-eating and Zoanthid-eating aeolids, Berghia, etc.).
- The vast majority feed on hydroids (although some also prey on other opisthobranchs or their eggs, corals, gorgonians, sea anemones, bryozoans or tunicates).
A few Nudibranch Exceptions for reef tanks:
- There are some true nudibranchs that can do well in aquaria, and one of the most popular species is Berghia verrucicornis. Berghia are being actively cultured for addition to aquaria plagued by those pesky glass anemones, Aiptasia.
- And, there is even a filter-feeding dendronotid nudibranch, Melibe leonina, that can be maintained on feedings of enriched brine shrimp in aquaria! I've had the opportunity to smell the mucus of a cold-water Melibe species that lives in kelp forests, and the mucus smells like watermelons! There is an odd bit of trivia for you.
http://www.nudipixel.net/
Nudi Pixel is a web-based identification tool for nudibranchs worldwide using photographs as the first point of identification. It is underpinned by up to date scientific classification. User-friendly, as it is designed with non-scientist users in mind.
http://www.seaslugforum.net/
On the
Sea Slug Forum you can find out more about nudibranchs, bubble-shells, sea hares and other sea slugs. This site aims to generate more interest in these fascinating animals by sharing information with a worldwide audience. The Forum is a useful tool for anyone with an interest in sea slugs from scientists and students to divers and aquarists.