''Megabalanus stultus'' is a species of

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

first described by

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...

in 1854. It lives on

fire coral Fire corals (''Millepora'') are a genus of colonial marine organisms that exhibit physical characteristics similar to that of coral. The name coral is somewhat misleading, as fire corals are not true corals but are instead more closely related ...

s of the genus ''Millepora'' in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

from Florida to southern Brazil.

Ecology

Millepora alcicornis (Branching Fire Coral)

''Megabalanus stultus'' is one of three species of barnacle that live on

s (the genus ''Millepora''). '' Savignium milleporae'' lives in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

and lives on 9 species of ''Millepora''; ''Megabalanus ajax'' lives in the western Pacific and lives on ''

Millepora platyphylla ''Millepora platyphylla'' is a species of fire coral, a type of hydrocoral, in the family Milleporidae. It is also known by the common names blade fire coral and plate fire coral. It forms a calcium carbonate skeleton and has toxic, defensive po ...

''; ''Me. stultus'' lives in the western Atlantic, and lives on '' Mi. alcicornis'' and '' Mi. complanata''. The nature of the relationship between ''M. stultus'' and the coral is unclear. At low densities, the barnacle has no discernible effect on the coral, but high-densities of coral-inhabiting barnacles can disrupt the growth of the colony.

Distribution

In his original description of the species, Darwin reported that ''M. stultus'' occurred in

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

and the

West Indies The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greater A ...

. In 1968, Arnold Ross considered the reports of ''M stultus'' from the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

to be erroneous, limiting the type locality to the West Indies. ''M. stultus'' has subsequently been reported from

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

in the western Pacific, and those records have been reassessed as referring to the related species ''

Megabalanus ajax ''Megabalanus'' is a genus of barnacles in the family Balanidae. Members of the genus grow to in length and inhabit the lower intertidal zone. Morphology ''Megabalanus'' is an acorn barnacle, a sessile crustacean that secretes a calcium carbon ...

''. ''M. stultus'' is now thought to occur exclusively in the western Atlantic, including the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

, from

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

Rio de Janeiro Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a b ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Description

''Megabalnus stultus'' differs from the other species of ''

Megabalanus ''Megabalanus'' is a genus of barnacles in the family Balanidae. Members of the genus grow to in length and inhabit the lower intertidal zone. Morphology ''Megabalanus'' is an acorn barnacle, a sessile crustacean that secretes a calcium carbon ...

'' in that the basal margin is sinuous, rather than straight, and protrudes medially, whereas in other species it protrudes little if at all. The shell is "dirty white" in colour, often with a purple tinge, and pale blue in parts.

Taxonomic history

''Megabalanus stultus'' was first described by

in 1854, under the name ''Balanus stultus''. It was placed in the subgenus ''

'' by Ross in 1968, which was raised to the rank of genus in 1976.

Ecology

Distribution

Description

Taxonomic history

References

Further reading