Nudibranchs
Top row: Shaggy Mouse Nudibranch, Clown Nudibranch.
Bottom row: Leopard Nudibranch, Monterey Sea Lemon.
Photos by Mary Jo Adams. Copyright 2004.
Up until the time I joined Beach Watcher Extraordinaire Mary Jo Adams on a low tide nighttime tidepool prowl one recent dark and starry night, nudibranchs were simply colorful and interesting creatures I had seen as photographs in books, in natural world videos and television programs, or in aquariums -- creatures biologists and scientists saw out there in the deep -- delicate, shell-less, soft-bodied animals closely related to snails. I felt I perhaps would never see one in their natural habitat -- Sir David Attenborough, and Jacques Cousteau would perhaps, but not mine self.
But thanks to Mary Jo's series of dark-hour treks and the supportive hands of others accompanying her, I too was able to see at least four "sea slug" species that memorable evening -- indeed organisms of spectacular colors and patterns -- garb that apparently warns potential predators they may be unpalatable -- unpleasant tasting. What an effective stay-alive technique! And the slugs, illuminated by our bright artificial lantern lights, couldn't have looked more resplendent -- the color of some that eat brightly colored creatures such as some of the sponge species was even revealed in the nudibranchs' own coloration.
The Orange Spotted or Sea Clown Nudibranch was one hard to forget with its cylindrical, several inch long, rather translucent to opaque appearing white bod and spectacularly brilliant orange spots and orange tips on a number of small, extruding projections, antennae, and gills. As all nudibranchs, each Triopha catalinae had a pair of delicate antenna-like projections near the head which Mary Jo said were called rhinophores -- structures helping the nudibranch to detect chemicals in the surrounding water -- chemicals perhaps associated with potential food sources.
Another stunner was the Ringed, Spotted, or Leopard Nudibranch, Diaulula sandiegensis. As its common names imply, another perhaps two inch long opaque whitish bod, but this one appearing velvety smooth and covered somewhat randomly with various sized and shaped rings or spots. Feeding on sponges gives them the where-with-all to lay up to a staggering 16 million eggs!
The Monterey Sea Lemon, Archidoris montereyensis, yet another handsome sighting. Again the specimens we saw were 2-3 inches long and they can reach six inches. It is also a sponge eater -- it remains an unanswered question how the sponge spicules can move through the digestive tract without causing harm. Common and rather flattish and orangish to yellow, the Monterey Sea Lemon looks very much like a lemon adhered to the rocky substratum.
Yet another interesting sighting was the Shaggy Mouse Nudibranch, Aeolidia papillosa -- indeed a stubbier, grayish, shaggy mouse kinda looker with lots of projections -- projections that look like tentacles and give it an anemone like look. But in this guise, this sturdy nudibranch actually seeks out anemones as food -- most partial to Metridium senile, the Plumose of Frilled Anemone. These "mice of the sea" tend to take on the color of the anemones on which they feed. The many shaggy projections are called cerata and serve to increase the body surface which absorbs dissolved oxygen from the water.
Thanks again, Mary Jo, for this awesome experience -- this chance to see up close and personal not only nudibranchs but so many other fascinating marine creatures as well.
And aren't we fortunate, not only to have Mary Jo as our enthusiastic, informative leader, but to live in a part of the planet so richly endowed with such marvelous habitats for all this intertidal marine life? Hundreds of diverse and interesting species in this rugged yet fragile ecosystem; and it's all right here, beckoning us to study, delight-in, help protect, ooh and ah over.
Pat Nash
Beach Watcher
Class of '94