Urechis caupo

Urechis caupo is a plump, unsegmented, cylindrical pink worm growing to a length of up to 7 inches, with 5.5 inches being a more typical length. There are a pair of setae (bristles) on the ventral surface at the anterior end, and a distinctive ring of about ten setae around the anus at the posterior end. The proboscis is short. ==Distribution and habitat==

Shallow water in the northeastern Pacific Ocean is the habitat of U. caupo; its range extends from southern Oregon to northern Baja California. It lives in a burrow in muddy sand in the lower intertidal and the shallow subtidal zone. One such stranding took place on December 6, 2019, at Drake's Beach near Pt. Reyes. This was likely the result of recent storm weather which disturbed the worms' burrows. ==Ecology==

This spoon worm is a detritivore and creates a U-shaped burrow in the soft sediment of the seabed. When feeding, it presses a ring of glands at the front of the proboscis against the burrow wall and secretes mucus which sticks to the burrow wall. The worm continues to exude mucus as it moves backwards in the burrow, thus creating a mucus net. The worm draws water through its burrow by peristaltic contractions of its body and as food particles pass through the net they adhere to it. When enough food is gathered, the worm moves forward in its burrow and swallows the net and entangled food. Faecal pellets accumulate around the worm's anus, and periodically the worm contracts its body sharply to produce a stream of water from the anus that blasts the pellets and loose sediment from the tube, creating a casting on the surface of the sand. The gut of the spoon worm often contains many trophozoites of the protozoan Zygosoma globosum. The sexes are separate and fertilisation is external. The eggs are pinkish or yellowish and the sperm are white, being liberated into the water through a pair of modified nephridia. The larvae are planktonic for about sixty days before settling on the seabed; they are strongly attracted to settle in the vicinity of other spoon worms by a chemical released from the castings. ==References==