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 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 whales in San Diego Bay, 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 found attached exclusively to the skin of whales, almost always to the gray whale, but occasionally it has been found on the killer whale and the beluga whale. 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 crustaceans known as whale lice, including the gray whale louseCyamus scammoni and the generalist whale liceCyamus ceti and Cyamus kessleri''. So common are these that an adultgray 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.