New nudibranchs at the Seattle Aquarium

opalescent nudibranch at the Seattle Aquarium

Opalescent nudibranch

Nudibranchs, members of the sea slug family, come in an amazing variety of shapes and colors. Several outstanding specimens were recently placed on exhibit at the Aquarium’s Closer Look table: the opalescent nudibranch, Hermissenda crassicornis; the alabaster or white-lined nudibranch, Dirona albolineata; and the Monterey sea lemon, Doris montereyensis.

white-lined nudibranch at the Seattle Aquarium

White-lined nudibranch

Monterey sea lemon at the Seattle Aquarium

Monterey sea lemon

Opalescent nudibranchs’ colors are variable but an orange and white strip down the dorsal (back) side is one of their distinguishing features. The pointed projections on their backs are called cerata and, among other things, they contain unfired nematocysts, or stinging cells, that the nudibranch acquired from its prey. When threatened by a kelp crab or other predator, opalescent nudibranchs may release a single cerata or a cluster of them as a defense.

The alabaster or white-lined nudibranch and the bright yellow Monterey sea lemon share a similar diet with the opalescent nudibranch: anemones, cup corals and sea pens. Like all nudibranchs, they use the radula (a band bearing numerous, very small teeth) in their head region to gnaw at their prey.

Come see the new nudibranchs the next time you visit the Seattle Aquarium!

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2 Responses to New nudibranchs at the Seattle Aquarium

  1. Hi
    I understand that keeping nudibraches in salt water aquariums is very difficult because of their food requirements. I would be interested in knowing how you keep these three species supplied with their required diets. I would very much like to see our local aquarium display these three same species. Thanks – Mike

    • Hello! Thanks for your interest in our temporary exhibits. We rarely get to display the many species of nudibranchs we have in our area, mostly because of asked about – lack of appropriate food supply. Our blog stated a number of food items believed to be consumed by these species. Unfortunately, that was more speculation than fact. The Monterey Sea Lemon is known to eat sponge, the Alabaster’s food preferences are relatively unknown, and the Hermissenda grazes happily on a number of food sources which occur naturally in our exhibits…we just don’t know exactly what they are! As a result, we only hold these animals for a short period of time. We set up the display on the Closer Look table to showcase them, but we intentionally only had the animals out for a short while before releasing them back into the wild. We have a strict policy of only displaying animals we can care for sustainably, and nudibranchs are a huge challenge to do so with our staffing resources. It would be great to initiate research to study these species to determin long-term holding menus, but we don’t have the folks to do it. So for now, most nudibranchs can only be short-lived members of our collection. Thanks again for your interest!

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