Arrow Worms: Chaetognatha

Physical characteristics: Pterosagitta draco worms have eight to ten hooks, six to ten front teeth, and eight to eighteen back teeth. The body length reaches 0.4 inches (11 millimeters), and the tail length is about one-third the length of the body. These worms have one pair of fins on the tail. The eyes are small with T-shaped color spots.

Geographic range: Pterosagitta draco (abbreviated to P. draco) worms live in the Atlantic, Pacific, and Indian oceans.

Habitat: P. draco worms live in warm and cool areas of the open ocean close to the surface.

Diet: P. draco worms eat tiny crustaceans.

Behavior and reproduction: P. draco worms feed at night. They make quick movements over short distances to catch prey. The worms make both eggs and sperm. Fertilized eggs are released into the water, where the worms hatch and grow into adults.

Pterosagitta draco worms feed at night. They make quick movements over short distances to catch prey. (Illustration by Joseph E. Trumpey. Reproduced by permission.)

Pterosagitta draco and people: P. draco worms have no known importance to people.

Conservation status: P. draco worms are not considered threatened or endangered. ∎