Armoured Sea Cucumber

Rocks in exposed and sheltered inlets.

Geographical Range: Pribilof Islands and Gulf of Alaska to Baja California

Depth Range: Low intertidal zone to subtidal depths of 247m

Looks much like a chiton, especially when the oral tentacles are retracted. Shape is like a cucumber that has been sliced in half lengthwise as the soft, orange ventral side is almost perfectly flat. Ventral side is covered in tube feet. Upper surface is covered with overlapping calcareous plates, which are usually a reddish-orange color. The mouth is located on the upper surface some distance from the anterior end and is surrounded by 10 bright red oral tentacles of equal length. Length to 7 cm.

How to Distinguish from Similar Species: Psolidium bidiscum is more purplish in color and is smaller.

Biology/Natural History: P. chitonoides is essentially sedentary. The cucumber uses its ten equal tentacles to filter detritus from the water. Sticky pads on each tentacle capture the food particles. The tentacles contain toxic compounds called saponins to discourage fish from nibbling at them. Predators that ignore these chemicals or are not affected by them include Stimpson