Thursday, May 14, 2015

Introducing New Tide Pool Animals

Please welcome our new tide pool animals, who have just completed quarantine. These animals were generously shared by Highline College’s MaST program.

Decorator Crab, Oregonia gracilis
This crab’s carapace is equipped with specialized hooked setae (bristles). It hooks bits of plant and shell onto these to camouflage its profile. Mature crabs decorate themselves less, but are often colonized by small organisms looking for a place to live. Decorator crabs eat carrion. We will feed it scallops.

California Sea Cucumber Parastichopus californicus
Sea cucumbers can eject their internal organs, or eviscerate, as a defense mechanism. They can then regenerate new sets of organs. They also eviscerate as an annual renewal during October and November. Gross fun fact: Recently this species has been discovered to take up nutrients via the respiratory tree in the anus especially in late winter/early spring when the animal was regenerating its gut. [Brothers et al. (2011)] Feeds on organic detritus and small organisms.

White Sea Cucumber, Eupentacta quinquesemita
Adults rarely expose their tentacles during daylight hours. Typically white sea cucumber have bits of shell and other materials attached here and there to the tube feet. During the evening, it will spread its tentacles to capture small food items and insert them into its mouth.

Leafy Horn Mouth, Ceratostoma foliatum
A large ornate, carnivorous snail eats mainly barnacles and bivalves. It drills through their shell with its radula, injects digestive enzymes and sucks out the dissolved tissue. We hope to keep ahead of this animal through collecting of barnacle rocks and small shellfish. This species can live up to 16 years, growing larger but also eroding its sharper edges as it matures.

Moon Snail Egg Cases, Euspira lewisii
We don’t introduce grown moon snails to the exhibit because they are voracious carnivores but we often find their egg cases on collecting trips. As reported in a previous blog post, moon snail sand collars make a cool discussion topic. They are a combination of sand, mucus, and eggs, which slowly disintegrate and release the eggs.

Hermit crabs, Pagurus hirsutiusculus and others
Hermit crabs have definite shell preferences, but these may be different in different places. The Bering hermit crabs we collect like shells too small to fully retract into. This is also true in the wild; we are not just offering undersized shells. Diet is mainly detritus.

Our tide pool contains hermit crabs that live in snail shells. We also have some of the snails themselves. Unlike the hermit crab, snails create their own shell and keep it throughout their lives. We allow handling of the hermit crabs but ask guests to leave the snails where they are. As on the beach, if something is attached, it is safest for the animal to leave it where it was found.

A good website to checkout more information about local tide pool invertebrates is “Invertebrates of the Salish Sea” - or come by and visit our display tide pool.

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