Opalescent Nudibranch

Opalescent Nudibranch20″x 24″

Opalescent Nudibranch
Hermissenda crassicornis


Friday Harbor Marine Laboratories, University of Washington
San Juan Island, Washington

Archival Pigment Print

Numerous orange-tipped tentacles called cerata (singular: ceras) are scattered along the back of this nudibranch. One function of the cerata seems to be helping the animal escape predation. In a set of laboratory experiments, researchers placed the nudibranchs in a tank with northern kelp crabs (Pugettia producta): When a crab grasped a nudibranch’s ceras in its claw, the slug immediately cast off the entire appendage, detaching it at its base. The crab was left with a squirming tentacle while the nudibranch rapidly escaped, gecko-style. Within a few days, regeneration of the lost ceras began, and within several weeks, the limb was as good as new.