Amphipods: Amphipoda

Physical characteristics: Unlike many amphipods, the yellow to orange bodies of this species are flattened top-to-bottom, not side-to-side. They measure up to 0.4 inches (10 millimeters). They use their hooklike claws to latch on to the skin of sperm whales. Their thoracic gills are clearly visible and resemble clumps of tiny fingers.

Geographic range: Sperm whale lice are found on sperm whales, which occur in all of the world's oceans.

Habitat: They live only on the bodies of sperm whales.

Diet: They scavenge organisms attached to the whale's skin and eat the skin itself.

Behavior and reproduction: Sperm whale lice spread to other whales by jumping onto them when infested whales rub up against other whales. Whale calves are infested by amphipods that come off their mothers when they touch.

Eggs are brooded in a pouch made by broad, leaflike appendages underneath the thorax. Newly hatched sperm whale lice strongly resemble the adults.

Sperm whale lice and people: This species does not impact people or their activities.

Conservation status: Sperm whale lice are not considered by the World Conservation Union (IUCN) to be threatened or endangered, although their only habitat, the sperm whale, is listed as Endangered, or facing very high risk of extinction in the wild. ∎

Sperm whale lice are found on sperm whales, which occur in all of the world's oceans. (Illustration by John Megahan. Reproduced by permission.)