Whales do not have hair, but like land mammals, they do have lice. This is how whalers called the crustaceans parasites from the Cyamidae family that coexisted with sea giants for millennia in the 19th century.
Whale lice have a flat body and, as a rule, do not exceed 2.5 cm in length. In the process of evolution, their legs acquired a pointed shape, which allows them to stick to the host's skin. They spend their entire life on the body of a whale, moving from mother to cub and from individual to another individual who is in close contact with her.
These parasites attach themselves to areas of the whale's body where they will be protected from water currents. For example, they settle in genital folds and natural openings, on wounds and skin around the eyes, as well as whale calluses. There they will feed on algae that have grown on the skin or flaky skin. During such a meal, whale lice can cause only minor damage to the skin, which will not lead to serious illness of the mammal.
Almost every whale species has a specific type of lice that do not live on other whales. In addition, some lice prefer to live and feed only on a specific part of the whale's body. For example, Cyamus ovalis lice tend to settle on calluses and the flaky scalp of a whale. The lice of C. gracilis live in depressions on the body, while C. erraticus takes refuge in the genitals of a whale. Since whale lice live in colonies, about 7, 500 of these parasites can live on one whale at a time.
Interestingly, tiny crustaceans today are helping scientists learn about the history of whales. For example, differences between certain genes in groups of lice suggest that right whales were divided into three separate species 5-6 million years ago, that is, northern, Japanese and southern right whales lived in isolation from each other for several million years.