Tuesday, April 21, 2015

Watch out for the coat!

On the underside of a rock at the end of the boat ramp at Boundary Bay - almost at the high tide line - I found a white and brown, squirmy, translucent bit of live jelly and wavy bits. It wouldn't sit still for its portrait, so I popped it in a bag with seaweed for protection, and brought it home.

He* wouldn't sit still in a bowl of clean water, either. I gave up and added him to the tank, where he promptly disappeared. He showed up two days later, and this time, he posed for me.

The opalescent nudibranch, Hermissenda crassicornis, hanging head down, belly outward. Isn't he beautiful?

Also known as the long-horned or thick-horned nudibranch, for the two long extensions in front. ("crassi ..." = L. "thick", "cornis" = L. "horn", as in unicorn, ".)

He's  about one inch long, usually, but sometimes stretches a good bit beyond. The "horns" are part of the foot. In this belly-forward photo, we can see the mouth and the two rhinopores. (More ancient languages, this time Greek: "rhinos" =  ῥινός, "nose", "phore" = φορος, "bearing".) All nudibranchs have these; they are scent or taste receptors. And on the right side, facing us, just above the head, that round, pearly button is the anus.

Along his back, he wears clumps of cerata, that function as gills; they wave about continuously in the current. In many of his cousins, the inner coloured area is orange; this guy only has tiny specks of orange.

Side view, showing the cerata and rhinophores.

He looks so soft and helpless; when my largest hermit came over to check him out, I cringed. Those huge pincers could have chopped him in two with no trouble, it seemed. But the hermit backed off and lost interest immediately. And "Herm" just kept on about his business, not in the least worried. He has his own hired bodyguards, in his coat.

This nudibranch eats anemones and hydroids. And digests everything but the stinging cells; those he stores in the tips of the soft cerata. And they still work, even in a foreign body, protecting the sea slug just as they protected the original anemones.

Browsing in the red algae; top of the head, with its distinctive markings.

He seems to have settled in happily to my aquarium; he wanders about, nibbling on whatever's growing on old stones and shells, and spending a lot of time in the red algae bushes.

 It eats hydroids, but the diet also includes small sea anemones, bryozoans, colonial ascidians (Aplidium solidum, botryllids), annelids, small crustacea, tiny clams, dead animals of any sort.  Will eat other Hermissenda. (From Wallawalla.edu.)

He shouldn't starve in the tank. Even though there's no other "Herm" for him to eat.

*These nudibranchs are hermaphroditic, with both male and female organs. Since this guy has no mate, he's not a mother, so "he" will do for him. For now.


  1. stunning photos as always

  2. I can't make head or tail of this beautiful creature - but beautiful it certainly is.

    (Wondering if you have a new camera. Your photographs are always interesting but these are spectacular.)

  3. Thank you!
    Lucy, no not a new camera, but I did invest in a really good tripod, which helps.


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