''Megabalanus'' is a genus 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 erosive ...

s in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Balanidae The Balanidae comprise a family of barnacles of the order Balanomorpha. As a result of research published in 2021 by Chan et al., the members of the family Archaeobalanidae were merged with this family. Genera These genera belong to the family B ...

. Members of the genus grow to in length and inhabit the lower

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

Morphology

''Megabalanus'' is an

acorn barnacle Acorn barnacle and acorn shell are vernacular names for certain types of stalkless barnacles, generally excluding stalked or gooseneck barnacles. As adults they are typically cone-shaped, symmetrical, and attached to rocks or other fixed objects ...

, a sessile crustacean that secretes a calcium carbonate shell consisting of five plates. It reaches up to in height .

Ecology

Like other barnacles, they are

suspension feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

s, grabbing particulate matter from the water column overhead. ''M. tintinnabulum'' has a worldwide distribution and is commonly found on wave-beaten shores, in the lower intertidal zone. They tend to grow in clusters of around 12 individuals. Other species are more select, such as ''M. californicus'' of tidal habitats in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

and the greater North American Pacific Coast. While many barnacles deal with competition for space by organisms such as

limpet Limpets are a group of aquatic snails that exhibit a conical gastropod shell, shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning the various groups called "limpets" ...

s and

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, whic ...

s by growing many organisms close together in colonies, ''Megabalanus'' responds by rapidly growing to a very large size. Their large size also helps reduce

predation Predation is a biological interaction In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or o ...

, although it makes them large enough to be harvested for human consumption.

Geological utility

Fossilised specimens of ''Megabalanus'' have been found dating back to the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

. Fossils bearing a close resemblance to ''M. tintinnabulum'' are preserved in large numbers in the Tabernas Basin of

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' ( Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...

. A case study of this area showed that the state of preservation of the organisms makes possible estimating the distance they were transported ''post mortem'' . Since the species today lives in the intertidal zone, this allows an estimate to be made of the distance from the shoreline, and by implication, the water depth. These observations are backed up by the appearance of the deep-water

trace fossil A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, ...

'' Zoophycum'' in the predicted deepest waters, suggesting that barnacles can be a good

proxy Proxy may refer to: * Proxy or agent (law), a substitute authorized to act for another entity or a document which authorizes the agent so to act * Proxy (climate), a measured variable used to infer the value of a variable of interest in climate re ...

for water depth.

Species

The World Register of Marine Species includes these species in the genus: * '' Megabalanus ajax'' (Darwin, 1854) * '' Megabalanus antillensis'' (Pilsbry, 1916) * '' Megabalanus azoricus'' (Pilsbry, 1916) (Azorean barnacle) * '' Megabalanus californicus'' (Pilsbry, 1916) (California barnacle) * '' Megabalanus clippertonensis'' Zullo, 1969 * '' Megabalanus coccopoma'' (Darwin, 1854) (titan acorn barnacle) * '' Megabalanus costatus'' (Hoek, 1913) * '' Megabalanus crispatus'' (Schröter) Darwin, 1854 * '' Megabalanus dolfusii'' (de Alessandri, 1907) * '' Megabalanus dorbignii'' (chenu, 1843) * '' Megabalanus galapaganus'' (Pilsbry, 1916) * '' Megabalanus giganteum'' (Kolosváry, 1949) * ''

Megabalanus honti ''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 carbo ...

'' (Kolosváry, 1950) * '' Megabalanus hungaricus'' (Kolosváry, 1941) * ''

Megabalanus javanicus ''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 ...

'' (Whithers, 1923) * ''

Megabalanus leganyii ''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 ...

'' (Kolosváry, 1950) * ''

Megabalanus linzei ''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 ...

'' (Foster, 1978) * '' Megabalanus multiseptatus'' (Ross, 1964) * '' Megabalanus occator'' (Darwin, 1854) * ''

Megabalanus peninsularis ''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 carbo ...

'' (Pilsbry, 1916) * ''

Megabalanus plicatus ''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 ...

'' (Hoek, 1913) * ''

Megabalanus rosa ''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 carbo ...

'' Pilsbry, 1916 (acorn barnacle) * '' Megabalanus seguenzai'' (de Alessandri, 1895) * '' Megabalanus spinosus'' (Gmelin, 1791) * ''

Megabalanus stultus ''Megabalanus stultus'' is a species of barnacle first described by Charles Darwin in 1854. It lives on fire corals of the genus ''Millepora'' in the Atlantic Ocean from Florida to southern Brazil. Ecology ''Megabalanus stultus'' is one of thre ...

'' (Darwin, 1854) * ''

Megabalanus tanagrae ''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 carbo ...

'' (Pilsbry, 1928) * '' Megabalanus tintinnabulum'' (

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, t ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of ''Systema Naturae'', the starting point of modern zoological ...

) (titan acorn barnacle) * '' Megabalanus transsylvanicus'' (Kolosváry, 1950) * '' Megabalanus transversostriatus'' (Beurlen, 1958) * '' Megabalanus tulipiformis'' (Ellis, 1758) * '' Megabalanus validus'' Darwin, 1854 * ''

Megabalanus venezuelensis ''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 carbo ...

'' (Weisbord, 1966) * '' Megabalanus vesiculosus'' (Darwin, 1854) * '' Megabalanus vinaceus'' (Darwin, 1854) * ''

Megabalanus volcano ''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 ...

'' (Pilsbry, 1916) * ''

Megabalanus xishaensis ''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 carbo ...

'' (Ren & Liu, 1978) * '' Megabalanus zebra'' Russell et al., 2003

References

{{Taxonbar, from=Q3282981 Barnacles Extant Miocene first appearances