Acorn Worm Phylum: Sub-Phylum:   Class: Species: Chordata Hemichordata Enteropneusta Acorn Worm

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The are about 70 species of Acorn Worms, ranging from 20 to 76 in. (50 to 190 cm) in length. The body has three main parts, the front one is acorn-shaped and known as the Proboscis. A short, fleshy collar lies just behind the Proboscis. The rest of the body is known as the trunk.

Acorn worms live on the sea-bead, from the shoreline down to the depths of 10,000 ft. (3,050 m).

Each animal normally digs itself a U-shaped burrow and lives there with the proboscis sticking out of one opening. Water and debris is drawn in through the mouth, which is at the junction of the proboscis and the collar. The water then flows out through the gill slits, but food particles are passed further down the digestive tract.

The sexes are separte. Eggs and sperm are merely shed into the water and fertilization occurs by chance. Most eggs are very small and they produce small Larvae, which swim freely in the plankton for a short while before settling on the sea-bed.