''Cryptolepas rhachianecti'' is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

whale barnacle Whale barnacles are species of acorn barnacle that belong to the family Coronulidae. They typically attach to baleen whales, and sometimes settle on toothed whales. The whale barnacles diverged from the turtle barnacles about three million year ...

that lives as a

passenger A passenger (also abbreviated as pax) is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The ...

on the skin of

gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bre ...

s and certain other species of whale in the northern Pacific Ocean.

Description

''Cryptolepas rhachianecti'' can grow to a diameter of .

Distribution

The species is now only known from the northern Pacific Ocean where gray whales are found. The gray whale was present in the northern Atlantic Ocean between the

Late Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within ...

and recent times, and ''C. rhachianecti'' fossils have been found on a beach in the Netherlands, showing that the barnacle must also have been present. This barnacle has been found between January and March for several years in captive

beluga whale The beluga whale () (''Delphinapterus leucas'') is an Arctic and sub-Arctic cetacean. It is one of two members of the family Monodontidae, along with the narwhal, and the only member of the genus ''Delphinapterus''. It is also known as the whi ...

s in

San Diego Bay San Diego Bay is a natural harbor and deepwater port located in San Diego County, California near the U.S.–Mexico border. The bay, which is long and wide, is the third largest of the three large, protected natural bays on California's of ...

, near a route used by migratory gray whales. The barnacles have evoked a skin reaction in the beluga whales resulting in the eviction of the barnacles, which suggests an immune response.

Ecology

This barnacle is exclusively found attached to the skin of whales, almost always to the

(''Eschrichtius robustus''), but occasionally it has been found on the

killer whale The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only extant species in the genus '' Orcinus'' and is recognizable by its black-and-white ...

(''Orcinus orca'') and the

(''Delphinapterus leucas)''. On the gray whale, the barnacles embed themselves deeply in the skin and are mostly clustered on the animal's head and back. Crawling among the barnacles and taking advantage of the protection they provide are several species of

ectoparasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

crustaceans known as

whale lice 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, most species of which are found in shallower waters. Whale lice are extern ...

, including the gray whale louse '' Cyamus scammoni'' and the generalist whale lice ''

Cyamus ceti ''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, most ...

'' and '' Cyamus kessleri''. So common are these that an adult gray whale may be carrying several hundred pounds weight of barnacles and lice. Gray whales have been observed rubbing their bodies against pebbly seabeds in an apparent effort to rid themselves of attached organisms.

References

{{Taxonbar, from=Q3698831 Barnacles Crustaceans of the Pacific Ocean Crustaceans of the eastern Pacific Ocean Crustaceans described in 1872 Taxa named by William Healey Dall