Psolus chitonoides

Psolus chitonoides, called the slipper sea cucumber, armoured sea cucumber, creeping armoured sea cucumber, or creeping pedal sea cucumber, belongs to the family Psolidae. Its scientific name means "resembling a chiton." This species lives in shallow waters along North America's western coast.

The body is oval, about 7 cm long and 5.8 cm wide, with a domed upper surface and a flat underside covered in tube feet. A staggered row of large tube feet runs down the center of the sole, with one or two rows of stout tube feet near each edge, plus a single row of smaller feet set in pits along the margins. At one end is the mouth, surrounded by a ring of eight to ten repeatedly branched tentacles—either all the same size or with two smaller than the rest.

The anus sits on the dorsal surface at the opposite end. The skin is leathery and somewhat spiny, protected by rows of stiff, overlapping scales that range from yellow to bright orange. The tentacles are red with white tips.

This sea cucumber was first discovered in 1886 in Puget Sound by Columbia University teams. Its range stretches from the Aleutian Islands to Baja California, inhabiting both exposed coasts and quiet inlets in the sublittoral zone down to about 247 m deep. Its soft, pliable sole allows it to stick to rocks, and it is commonly found clinging firmly to vertical rock faces.

It feeds by suspension, intercepting floating particles that get trapped by sticky papillae on its tentacles. High concentrations of saponins in its tissues make it toxic, and most predatory fish, gastropod molluscs, and crabs avoid it; its flesh is unpalatable to the tidepool sculpin. Its main predators are starfish, especially the leather star. Juveniles are photo negative, and the eggs are bright red.