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.

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.