Whale louse

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Whale lice
Cyamus boopis (dorsal).jpg
Cyamus boopis female
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Superorder: Peracarida
Order: Amphipoda
Suborder: Senticaudata
Infraorder: Corophiida
Parvorder: Caprellidira
Superfamily: Caprelloidea
Family: Cyamidae
Rafinesque, 1815

A whale louse is a commensal crustacean of the family Cyamidae. Despite the name, they are not true lice (which are insects), but rather are related to the skeleton shrimp, most species of which are found in shallower waters. Whale lice are external parasites, found in skin lesions, genital folds, nostrils and eyes of marine mammals of the order Cetacea. These include not only whales but also dolphins and porpoises.


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 5 to 25 millimetres (0.2 to 1 in) depending on the species.

Life cycle[edit]

Most species of whale lice are associated with a single species of whale. They remain with their host throughout their development and do not experience a free-swimming phase.[1] Although the relationship between a specific species of whale louse and a specific species of whale is more pronounced with baleen whales than with toothed whales, almost every species of whale has a louse species that is unique to it. With the sperm whale, the parasitic relationship is sex-specific. The whale louse Cyamus catodontis lives exclusively on the skin of the male, while Neocyamus physeteris is found only on females and calves.[2]

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.[3]

With some species of whale lice, whale barnacle infestations play an important role. On the right whale, 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 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 lice species reflects migratory patterns.

Orange whale lice on a right whale


Currently, 31 species are recognised:[4]

Cyamus Latreille, 1796
Isocyamus Gervais & van Beneden, 1859
Neocyamus Margolis, 1955
Platycyamus Lütken, 1870
Scutocyamus Lincoln & Hurley, 1974
Syncyamus Bowman, 1955


  1. ^ Kaliszewska, Z. A.; J. Seger; S. G. Barco; R. Benegas; P. B. Best; M. W. Brown; R. L. Brownell Jr.; A. Carribero; R. Harcourt; A. R. Knowlton; K. Marshalltilas; N. J. Patenaude; M. Rivarola; C. M. Schaeff; M. Sironi; W. A. Smith & T. K. Yamada (2005). "Population histories of right whales (Cetacea: Eubalaena) inferred from mitochondrial sequence diversities and divergences of their whale lice (Amphipoda: Cyamus)". Molecular Ecology. 14 (11): 3439–3456. doi:10.1111/j.1365-294X.2005.02664.x. PMID 16156814.
  2. ^ P. B. Best (1969). "The sperm whale (Physeter catodon) off the west coast of South Africa. 3. Reproduction in the male". Division of Sea Fisheries Investigational Report. 72: 1–20. Cited in: Amy Samuels & Peter L. Tyack (2000). "Flukeprints: a history of studying cetacean societies". In Janet Mann; Richard C. Connor; Peter L. Tyack & Hal Whitehead (eds.). Cetacean Societies: Field Studies of Dolphins and Whales. University of Chicago Press. pp. 9–44. ISBN 978-0-226-50341-7.
  3. ^ "Crablike 'whale lice' show how endangered cetaceans evolved". University of Utah. September 14, 2005. Retrieved December 2, 2012.
  4. ^ C. De Broyer (2009). "Cyamidae". World Register of Marine Species. Retrieved April 8, 2010.