Urechis caupo, commonly known as the fat innkeeper worm, are a species of spoon worm in the Urechidea family. Found in shallow water on the west coast between Oregon and Baja California. The Innkeeper worm forms U Shaped burrows in the sediment and using a mucus net feeds on plankton. The common name Fat innkeeper worm came about because the worm share it burrow with other animals.
The innkeeper worm can grow to 20 inches long but 8in is a more typical length.
This plump, unsegmented, cylindrical pink worm is a detritivore, eating organic matter that is breaking down on the sea floor. The innkeeper worm does this by pressing a ring of glands against the burrow walls. The glands secrete a mucus which sticks to the burrow walls, as the worm backs into the burrow it continues to exude a mucus, creating a mucus net. Through peristaltic contractions the worm draws water in trapping food particles in the mucus net. When enough food is caught the worm moves forward and ingest the mucus net food and all.
Food Particles that are too large and rejected and left in the burrows for other animals to eat including softshell clams, pea crabs, shrimp and scaleworms. The Arrow Goby uses the burrows when threatened.
There are 2 sexes for the innkeeper worm and the yellowish pinkish eggs are fertilized externally. The Larvae float around for about 60 days until the settle on the seabed. Through chemical attraction to adult castings the Larvea settle in the vicinity of other innkeeper worms.