A whale louse is a

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

of the family Cyamidae. Despite the name, it is not a true

louse Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result o ...

(which are

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s), but rather is related to the

skeleton shrimp Caprellidae is a family of amphipods commonly known as skeleton shrimps. Their common name denotes the threadlike slender body which allows them to virtually disappear among the fine filaments of seaweed, hydroids and bryozoans. They are sometim ...

, most species of which are found in shallower waters. Whale lice are external parasites, found in skin lesions,

genital A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, a ...

folds,

nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

s and eyes of

marine mammal Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their reli ...

s of the order

Cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

. These include not only

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s but also

dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...

s and

porpoise Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals an ...

Appearance

The body of a whale louse is distinctly flat and considerably reduced at the rear. Its legs, especially the back three pairs of legs, have developed into claw-like protuberances with which it clings to its host. Its length ranges from depending on the species.

Life cycle

Most species of whale louse are associated with a single species of whale. They remain with their host throughout their development and do not experience a free-swimming phase. Although the relationship between a specific species of whale louse and a specific species of whale is more pronounced with

baleen whale Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their ...

s than with

toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species of t ...

s, almost every species of whale has a louse species that is unique to it. With the

sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...

, the parasitic relationship is sex-specific. The whale louse '' Cyamus catodontis'' lives exclusively on the skin of the male, while ''

Neocyamus physeteris ''Neocyamus'' is a genus of amphipod belonging to the family Cyamidae A whale louse is a commensal crustacean of the family Cyamidae. Despite the name, it is not a true louse (which are insects), but rather is related to the skeleton shrimp, ...

'' is found only on females and calves. Whale lice attach themselves to the host body in places that protect them from water currents, so they can be found in natural body openings and in wounds; with baleen whales they are found primarily on the head and in the ventral pleats. Around 7,500 whale lice live on a single whale. With some species of whale louse, whale barnacle infestations play an important role. On the

right whale Right whales are three species of large baleen whales of the genus ''Eubalaena'': the North Atlantic right whale (''E. glacialis''), the North Pacific right whale (''E. japonica'') and the Southern right whale (''E. australis''). They are clas ...

, the parasites live mainly on callosities (raised callus-like patches of skin on the whales' heads). The clusters of white lice contrast with the dark skin of the whale, and help researchers identify individual whales because of the lice clusters' unique shapes. The lice predominantly eat

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

that settle on the host's body. They usually feed off the flaking skin of the host and frequent wounds or open areas. They cause minor skin damage, but this does not lead to significant illness. The development of the whale louse is closely connected with the life pattern of whales. The distribution of various louse species reflects migratory patterns. Orange whale lice right whale

Species

Currently, 31 species are recognised: ;'' Cyamus'' Latreille, 1796 *'' Cyamus antarcticensis'' Vlasova, 1982 *'' Cyamus bahamondei'' Buzeta, 1963 *'' Cyamus balaenopterae'' K. H. Barnard, 1931 *''

Cyamus boopis ''Cyamus boopis'' is a species of whale louse in the family Cyamidae. This is an ectoparasite that lives exclusively on humpback whales. The infestation is most concentrated around the genital apertures, but occurs on all parts of the body, mos ...

'' Lütken, 1870 *'' Cyamus catodontis'' Margolis, 1954 *'' Cyamus ceti'' (Linnaeus, 1758) *'' Cyamus erraticus'' Roussel de Vauzème, 1834 *'' Cyamus eschrichtii'' Margolis, McDonald & Bousfield, 2000 *'' Cyamus gracilis'' Roussel de Vauzème, 1834 *'' Cyamus kessleri'' A. Brandt, 1873 *'' Cyamus mesorubraedon'' Margolis, McDonald & Bousfield, 2000 *'' Cyamus monodontis'' Lutken, 1870 *'' Cyamus nodosus'' Lutken, 1861 *'' Cyamus orcini'' Leung, 1970 *'' Cyamus orubraedon'' Waller, 1989 *'' Cyamus ovalis'' Roussel de Vauzème, 1834 *'' Cyamus rhytinae'' (J. F. Brandt, 1846) *'' Cyamus scammoni'' Dall, 1872 ;'' Isocyamus'' Gervais & van Beneden, 1859 *'' Isocyamus antarcticensis'' Vlasova in Berzin & Vlasova, 1982 *'' Isocyamus delphinii'' Guérin Méneville, 1836 *'' Isocyamus deltabrachium'' Sedlak-Weinstein, 1992 *'' Isocyamus kogiae'' Sedlak-Weinstein, 1992 ;''

Neocyamus ''Neocyamus'' is a genus of amphipod belonging to the family Cyamidae A whale louse is a commensal crustacean of the family Cyamidae. Despite the name, it is not a true louse (which are insects), but rather is related to the skeleton shrimp, m ...

'' Margolis, 1955 *''

'' (Pouchet, 1888) ;'' Platycyamus'' Lütken, 1870 *''

Platycyamus flaviscutatus ''Platycyamus'' may refer to: * ''Platycyamus'' (plant), a genus of plants in the family Fabaceae * ''Platycyamus'' (amphipod), a genus of whale lice in the family Cyamidae A whale louse is a commensal crustacean of the family Cyamidae. Despite ...

'' Waller, 1989 *'' Platycyamus thompsoni'' (Gosse, 1855) ;'' Scutocyamus'' Lincoln & Hurley, 1974 *'' Scutocyamus antipodensis'' Lincoln & Hurley, 1980 *'' Scutocyamus parvus'' Lincoln & Hurley, 1974 ;'' Syncyamus'' Bowman, 1955 *'' Syncyamus aequus'' Lincoln & Hurley, 1981 *'' Syncyamus chelipes'' (Costa, 1866) *'' Syncyamus ilheusensis'' Haney, De Almeida & Reid, 2004 *'' Syncyamus pseudorcae'' Bowman, 1955

References

* ''Much of the content of this article comes from the equivalent German-language Wikipedia article (September 2005).'' {{Taxonbar, from=Q1890501 Corophiidea Parasitic crustaceans Taxa named by Constantine Samuel Rafinesque