''Coronula diadema'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

whale barnacle 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 por ...

that lives on the skin of

humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the monotypic taxon, only species in the genus ''Megaptera''. Adults range in length from and weigh u ...

s and certain other species of whale. This species was first described by

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

in the 1767

12th edition 1 (one, unit, unity) is a number, numeral, and glyph. It is the first and smallest positive integer of the infinite sequence of natural numbers. This fundamental property has led to its unique uses in other fields, ranging from science to sp ...

of his ''

Systema Naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...

''.

Description

As its name suggests, ''Coronula diadema'' resembles a crown in appearance, but as it grows it becomes more cylindrical; large specimens may be tall and in diameter. There are six broad wall plates surrounding a hexagonal orifice at the top, which is protected by a pair of opercular valves. The plates have fine longitudinal striations and the lower half often have irregular transverse striations.

Distribution and habitat

''C. diadema'' is found on the external surface of whales. When discussing this species, the zoologist

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

(who devoted much of his career to barnacles) stated that he knew of the precise locations where four specimens were found, the arctic seas around Scandinavia, the east coast of North America, near the coast of the British Isles, and from the

Gulf Stream The Gulf Stream is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida and up the eastern coastline of the United States, then veers east near 36°N latitude (North Carolin ...

. Another reported location was New Zealand, but Darwin suspected that this was an error, and might be '' Coronula reginae''. The host whales are mostly

baleen whale Baleen whales (), also known as whalebone whales, are marine mammals of the order (biology), parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankt ...

s, particularly

s (''Megaptera novaengliae''), with the barnacles attaching themselves to the head, the flukes, the flippers, various grooves and the genital slit. This barnacle has also been found on the

blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known ever to have existed. The blue whale's long and slender body can ...

(''Balaenoptera musculus''), the

southern right whale The southern right whale (''Eubalaena australis'') is a baleen whale, one of three species classified as right whales belonging to the genus ''Eubalaena''. Southern right whales inhabit oceans south of the Equator, between the latitudes of 20� ...

(''Eubalaena australis''), the

fin whale The fin whale (''Balaenoptera physalus''), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured in length, wi ...

(''Balaenoptera physalus''), 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 (biology), genus ''Physeter'' and one of three extant species in the s ...

(''Physeter macrocephalus'') and the

northern bottlenose whale The northern bottlenose whale (''Hyperoodon ampullatus'') is a species of beaked whale in the ziphiid family, being one of two members of the genus '' Hyperoodon''. The northern bottlenose whale was hunted heavily by Norway and Britain in the 1 ...

(''Hyperoodon ampullatus''). For 'the role of ''Coronula diadema'' on a humpback whale's pectoral fins helping it to defend its calves from killer whales, see Humpback whale#Fins.

Life cycle

Most barnacles are

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

s and can fertilize each other but not themselves, so they need to be clustered closely together to be able to breed. An individual acting as a male extends his long

penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate. The term ''pen ...

to impregnate the mantle cavity of another individual in close proximity. Here internal fertilisation takes place and the embryos are brooded until the first moult. The free-swimming nauplius larvae form part of the

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

and pass through six moults before becoming non-feeding

cyprid Barnacles are arthropods of the subclass Cirripedia in the subphylum Crustacea. They are related to crabs and lobsters, with similar nauplius larvae. Barnacles are exclusively marine invertebrates; many species live in shallow and tidal water ...

larvae. Laboratory experiments suggest that the cyprid larvae are induced to settle and undergo

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

into juvenile barnacles in response to chemical cues from the skin of suitable host whales.

Gallery

References

External links

* {{Taxonbar, from=Q4302742 Barnacles Crustaceans described in 1767 Taxa named by Carl Linnaeus