Copepods: Copepoda

Physical characteristics: Adult females measure 0.039 to 0.059 inches (1 to 1.5 millimeters) in length, while males are 0.029 to 0.039 inches (0.75 to 1 millimeters). The fore body is egg-shaped and has a beaklike projection on the front. The female's antennules have very long hairlike structures, while those of the male are bent. The max-illipeds are well developed. The first four pairs of thoracic limbs are also well developed, but the last pair is small and feathery. Each has a bristle at the base. The abdomen is slender and is nearly equal in length to the fore body.

Geographic range: They are found in all oceans.

Habitat: Oithona plumifera live along coastlines and out in the open sea, from the surface down to 328 feet (100 meters).

Diet: They eat bits of tiny plants and animals floating in the water.

Oithona plumifera eat bits of tiny plants and animals floating in the water. (Illustration by John Megahan. Reproduced by permission.)

Behavior and reproduction: Their life cycle consists of six stages of nauplius larvae, followed by five larval stages resembling the adult.

Little is known about their mating behavior. Males and females probably meet in swarms in the water. The male probably grasps the female's fourth pair of thoracic limbs before depositing his sperm packet. The fertilized eggs are stored in a pair of sacs.

Oithona plumifera and people: Oithona plumifera forms an important middle link in the oceanic food web between tiny algae and commercially harvested fishes breeding in estuaries and in coastal waters.

Conservation status: This species is not considered threatened or endangered. ∎