Synaptula recta

The gut-like sea cucumber, Synaptula recta, is a member of the Synaptidae family within the phylum Echinodermata. It lives in shallow waters across the tropical Indo-Pacific. This species has an elongated body that can reach up to 40 cm (16 in) in length.

Its color varies widely, often appearing in deep shades such as dark reddish-purple, bright red, olive, or with longitudinal lilac stripes on a pale background. Thirteen feeding tentacles surround the mouth at the front end. The cuticle contains calcareous spicules shaped like anchors with knobbed ends and curved bodies; the spicule tips project through the skin to provide traction as the animal moves by peristalsis, since synaptids lack tube feet.

The species is found from the Red Sea, the Maldives, and Sri Lanka, through northern Australia, Indonesia, and the Philippines, to several Pacific island groups. It inhabits coastal waters, reefs, sand flats, and seagrass meadows, at depths down to about 20 m (66 ft).

Nocturnal by nature, it feeds on detritus and planktonic particles, sweeping them into its mouth with its tentacles, and is often seen moving over and feeding on debris on sponge surfaces. The sexes are separate, with external fertilization. The planktonic larvae first develop into auricularia, then into barrel-shaped doliolaria, which eventually settle on the seabed and metamorphose into juveniles.