The tentacles are repeatedly branched and number eight to ten, either all the same size or with two smaller than the rest.

[4] The slipper sea cucumber is found on the western coast of North America, its range extending from the Aleutian Islands to Baja California.

It occurs on both exposed coasts and in quiet inlets, in the sublittoral zone down to depths of about 247 m (800 ft).

[2] The slipper sea cucumber is a suspension feeder, intercepting particles floating past which are then trapped by sticky papillae on its feeding tentacles.

This makes it toxic and it is avoided by most predatory fish, gastropod molluscs and crabs; its flesh has been shown to be unpalatable to the tidepool sculpin (Oligocottus maculosus).