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Shaggy Mouse Nudibranch The word "NUDIBRANCH" doesn't exactly slip off the tongue but it helps if you tackle it in two parts: Nudi (naked) and Branchs (Lungs). Put them together and you have "NOODI-BRANKS." They got that name because their gills are external--they have naked lungs! (Or you can just call these strange shell-less snails Sea Slugs, because that's just what they are.)
Nudibranchs are mollusks--just like oysters, clams, snails, squid and octopus. Nudibranch start out life with shells but they discard
them as they mature and grow.
(Shaggy Mouse Nudibranch photo courtesy of Gary Hayes)

Haystack Rock is home to many different kinds of nudibranches, including: Sea Lemons, Red Sponge Nudibranchs, Alabaster Nudibranchs, Opalescent Nudibranchs, Clown Nudibranchs, Shaggy Mouse Nudibranchs, the Rough Mantled Doris and--if you can believe it--many more!

Sea Clown NudibranchSpotting these often-colorful creatures in a tidepool is a great reward for those who take the time to watch and wait. It is our experience that once you find one nudibranch, finding more is easy!
You just need to know what to look for and, more importantly, where to look. Check your tidepool field guides to find out where each different species resides, what it eats, and when it is active. Sea Clown Nudibranch (3 in.) © Patten, California Academy of Sciences

Sea lemons, for example, can usually be found in and around patches of Bread Crumb Sponge--because that is what it eats! Shaggy Mouse Nudibranchs, on the other hand prefer to eat aggregating anemones. In fact once the Shaggy Mouse is immune to the anemone's sting, it eats at least once a day and consumes up to 100% of it's own body weight.

Frosted NudibranchThe Alabaster or Frosted Nudibranch feeds on snails by using it's powerful 'jaws' to crack open the snail's shell. It also eats sea squirts, anemones, and bryozoans (moss animals). Alabaster Nudibranchs are more likely to be seen on extreme low tide days, while the Opalescent/Hermissenda Nudibranch is more common--and is especially abundant in June and July.Because nudibranchs do not have shells, they are fragile creatures. If you spot one in a tidepool or on a rock, it is best to watch and learn--and then leave it alone.
Opalescent/Hermissenda Nudibranch (1.5-3 in) © Gary Hayes, Pelican Productions

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