Echinophthiriidae

Echinophthiriidae is a family of lice in the suborder Anoplura, the sucking lice. This family of lice are parasites of seals and the river otter, and are the only insects that infest aquatic hosts. thumb|upright=1.1|Antarctophthirus trichechi These lice have adaptations influenced by the anatomy of their hosts. Because some marine mammals, such as fur seals, have a layer of air trapped under their waterproof coats that insulates them against cold water, their lice actually live in a mostly dry, warm habitat. Other mammals have blubber for insulation, so their skin is in contact with the water; their lice parasites live in a cold aquatic environment.

Lice in this family have a chaetotaxy characterized by three kinds of setae: spines, scales, and hairs. Different species have different arrangements of these setae. Species also have various egg-laying habits, with some laying them singly or in clusters, and some cementing them to the hairs of the host animal. These lice have antennae but no eyes. In most species the middle and rear pairs of legs are larger with blunt claws while the front pair of legs is smaller with pointed claws. Scanning electron microscope examination shows that the species Antarctophthirus microchir uses its larger middle and rear pairs of legs to cling to the hairs of its host, and the smaller, pointed front legs are probably sensory structures.