Q: What is a nudibranch?
A: A sea slug; "branch" (slang); naked snail; members of the subclass Opisthobranchiata belonging to the class Gastropoda in the Phylum Mollusca; a suborder of molluscs lacking a shell as adults and having external respiratory appendages usually on the dorsal surface. Their taxonomic classification is as members of the class Gastropoda, subclass Opisthobranchia, order Nudibranchia.

Q: What's so great about these critters?
A: They are probably the most beautiful creatures in the ocean! There are over 3000 species worldwide- they're fascinating, easy to follow once found, and make great photography subjects. They don't bite you, emit a foul odor, sneak up behind you, or otherwise ruin your day. They don't make good pets so they're not over-collected by divers, but they are rare enough to command your attention when seen. When you see a variety you haven't seen you never know if it's one that has been taxonomically classified and given a species name, or one that nobody has had the opportunity to classify (another good reason to take a photograph!)

Q: How big are they?
A: Most are small, about 1-2 inches or less, though some species such as the Spanish dancer may grow up to 19 inches in length or more. If you search for them under rocks, you are more likely to encounter the smaller variety; if you scan the reef underwater from a distance, you are more likely to see a brightly colored, larger species. If you slowly scan the reef from a very close distance (2-3 feet), you are more likely to encounter the well-disguised variety that utilizes protective coloration to disguise itself against the background of the coral reef and algae.

Q: Where do nudibranchs live?
A: In the ocean, exclusively. Most live near the shore, in tidal pools, and in shallow waters readily accessible to the scuba diver. I have never seen one diving in the Caribbean (though I have seen colorful snails with shells, such as flamingo tongues). They are prolific throughout the Indo-pacific region, the west coast of the U.S., Hawaii, and Guam, to name a few of the Pacific ocean regions they populate.

Q: Can I collect them for my salt-water aquarium?
A: Nudibranchs don't survive long at all in an aquarium, because of their special diets. When was the last time you saw one in a public aquarium? What about in a tropical fish store? What about mounted on the wall as a trophy? As preserved specimens, they lose their color and shape. The best way to view them is in their natural habitat, and the best way to remember them is through photographs.

Q: How do nudibranchs reproduce?
A: Nudibranchs are hermaphroditic, meaning they possess both male and female sex organs. Mating nudibranchs exchange sperm through a common aperture, a protruding tube on the side of their body which joins a similar aperture on the mating partner. Eggs are laid in rose-like egg masses in the dorid nudibranchs, as compared to tube-like egg strings in the aeolid nudibranchs. Incubation of the eggs can be up to 50 days, but normally is much shorter.

Q: What is the difference between dorid nudibranchs and aeolid nudibranchs?
A: Both are suborders of the order Nudibranchia, with aeolids (a.k.a. eolids) being a type of nudibranch possessing cerata rather than a feather-like external gill on the back and no rhinophoral sheath. Most of the photos shown on my page are dorid nudibranchs, as are most of the species I have encountered. Generally, aeolids are longer and thinner, and dorids are shorter and fatter. Dorid nudibranchs are named for the sea goddess, Doris, daughter of Oceanus and mother of the Nereides. Aeolids are named after the Greek god, Aeolis, god of the wind.

Q: How do you find nudibranchs?
A: I think the best way is to pay careful attention to the details of the reef while scuba diving-- meaning staying 2-3 feet from the reef, slowly moving, and carefully observing for nudibranchs. Another good place to find small nudibranchs is underneath rocks or debris. Coral heads are great for nudibranchs since they are populated with sponges, tunicates, anemones, individual corals, hydroids, and other nudibranch food.

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