''Megabalanus stultus'' is a species of

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

first described by

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 ...

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 t ...

s of the genus ''Millepora'' in the Atlantic Ocean from Florida to southern Brazil.

Ecology

''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''; ''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 and the

West Indies The West Indies is an island subregion of the Americas, surrounded by the Atlantic Ocean, North Atlantic Ocean and the Caribbean Sea, which comprises 13 independent island country, island countries and 19 dependent territory, dependencies in thr ...

. In 1968, Arnold Ross considered the reports of ''M stultus'' from the Pacific Ocean 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. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

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 carbona ...

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

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

, from Florida to

Rio de Janeiro Rio de Janeiro, or simply Rio, is the capital of the Rio de Janeiro (state), state of Rio de Janeiro. It is the List of cities in Brazil by population, second-most-populous city in Brazil (after São Paulo) and the Largest cities in the America ...

, Brazil.

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