| Bay barnacle | |
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Thecostraca |
| Subclass: | Cirripedia |
| Order: | Balanomorpha |
| Family: | Balanidae |
| Genus: | Amphibalanus |
| Species: | A. improvisus |
| Binomial name | |
| Amphibalanus improvisus | |
Amphibalanus improvisus, the bay barnacle, European acorn barnacle, is a species of acorn barnacle in the family Balanidae.
Amphibalanus improvisus has a smooth white or pale grey conical calcareous shell composed of six fused plates. There is an oval or rhombic opening at the top which is blocked by two hinged plates. [3] Adults usually grow to about 10 mm (0.4 in) in diameter and 6 millimetres (0.24 in) in width though they are sometimes larger than this and can grow taller when densely packed. The base is characteristically grooved radially. This species can be confused with the striped barnacle ( Amphibalanus amphitrite ) [4] and in European waters with the northern rock barnacle ( Semibalanus balanoides ) or the rock barnacle ( Balanus crenatus ). [5]
Amphibalanus improvisus has a cosmopolitan distribution and is found in temperate and tropical parts of the Atlantic Ocean, the Arctic Ocean, the Baltic Sea the North Sea, the Mediterranean Sea and the Black Sea. It is not known where the species natural range lies but it may have originated in North America. It has colonised many parts of the world's oceans including the Indo-Pacific and Australasia as a biofouling agent on the hulls of ships. [3] It was one of the first recorded introductions to the Baltic Sea, having been found in Sweden and Lithuania in 1844, the Elbe estuary in 1854 and Great Britain in the 1880s. [5]
Amphibalanus improvisus is found, sometimes in vast numbers, down to a depth of about 6 metres (20 ft) on rocks, man made structures, buoys, ships' hulls, the shells of crabs and molluscs, and certain seaweeds. It has been known to block the water intake pipes of factories and power stations. It is tolerant of both high and low salinity levels and is often found in estuaries and low salinity bays. As an invasive species it competes with native organisms and it is an unwanted coloniser of the shells of cultivated oysters and mussels and aquaculture cages. [5] [6]
Amphibalanus improvisus is a filter feeder. It extends its six pairs of modified legs called cirri to catch plankton and other organic material floating past. It is a hermaphrodite and sperm is passed into the cavity of a neighbouring barnacle through a long penis. The eggs are fertilised and brooded in the cavity and hatch into nauplius larvae which drift with the currents. After six naupliar stages occupying two to five weeks, these become cyprid larvae and find a suitable surface on which to settle. Here they cement themselves to the substrate and undergo metamorphosis into juveniles. There may be several broods in the year but usually just two in the cooler waters of the Baltic and only one in low salinity environments. [6] [7]
Barnacles are a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and are hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. Around 1,000 barnacle species are currently known.
Balanus is a genus of barnacles in the family Balanidae of the subphylum Crustacea.
Austrominius modestus is a species of barnacle in the family Elminiidae, native to Australia, Tasmania and New Zealand, but now spread to Britain and the north west coasts of Europe. It reaches a maximum size of about 10 millimetres in diameter.
The Chthamalidae are a family of chthamaloid barnacles, living entirely in intertidal/subtidal habitats, characterized by a primary shell wall of eight, six, or four plates, lacking imbricating plate whorls, and either membraneous or more rarely calcareous basis. They are not found below immediate subtidal habitats, and more likely are found in the highest tier of shallow-water barnacle fauna. They can be found in the most rigorous wave-washed locations, and some species are found in the surf zone above high tide mark, only receiving water from wave action at high tide.
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 in the ocean. Members of the barnacle order Balanomorpha are often called acorn barnacles.
Semibalanus balanoides is a common and widespread boreo-arctic species of acorn barnacle. It is common on rocks and other substrates in the intertidal zone of north-western Europe and both coasts of North America.
Balanus nubilus, commonly called the giant acorn barnacle, is the world's largest barnacle, reaching a diameter of 15 cm (6 in) and a height of up to 30 cm (12 in), and containing the largest known muscle fibres.
Balanus balanus is a species of acorn barnacle in the Balanidae family. It is native to the colder seas of the northern hemisphere.
Balanus crenatus is a species of acorn barnacle in the Balanidae family. It is found in the North Pacific and the North Atlantic Ocean.
Amphibalanus amphitrite is a species of acorn barnacle in the Balanidae family. Its common names include the striped barnacle, the purple acorn barnacle and Amphitrite's rock barnacle. It is found in warm and temperate waters worldwide.
Balanus perforatus is a species of barnacle in the family Balanidae. It is found on the lower shore and in the neritic zone in the warm temperate parts of the eastern Atlantic Ocean.
Pollicipes polymerus, commonly known as the gooseneck barnacle or leaf barnacle, is a species of stalked barnacle. It is found, often in great numbers, on rocky shores on the Pacific coasts of North America.
Notochthamalus scabrosus, the only species in the genus Notochthamalus, is a species of barnacle found along the south-western and south-eastern coasts of South America, from Peru to the Falkland Islands. The species is found almost exclusively higher in the intertidal zone than the mussel Perumytilus, often codistributed with the confamilial barnacle Jehlius cirratus and Balanus flosculus.
Megabalanus tintinnabulum is a species of large barnacle in the family Balanidae. It is the type species of the genus. The specific name comes from the Latin tintinnabulum meaning a handbell and probably refers to the fact that small groups of barnacles resemble clusters of miniature bells.
Amphibalanus eburneus, the ivory barnacle or American acorn barnacle, is a species of acorn barnacle in the family Balanidae. It occurs on the east coast of North America, the Caribbean Sea and Gulf of Mexico.
Megabalanus coccopoma, the titan acorn barnacle, is a tropical species of barnacle first described by Charles Darwin in 1854. Its native range is the Pacific coasts of South and Central America but it is extending its range to other parts of the world.
Catomerus is a monotypic genus of intertidal/shallow water acorn barnacle that is found in warm temperate waters of Australia. The genus and species is very easily identified by whorls of small plates surrounding the base of the primary shell wall; no other shoreline barnacle species in the Southern Hemisphere has that feature. This species is considered to be a relic, as these plates are found only in primitive living lineages of acorn barnacles or in older fossil species. The fact that this is an intertidal species is unusual, because living primitive relic species are often found in more isolated habitats such as deep ocean basins and abyssal hydrothermal vents.
Catophragmus is the originally named genus of the family Catophragmidae. At present, it is monotypical. It is a shallow water acorn barnacle of the Tropical Western Atlantic and Caribbean characterized by small accessory imbricating plates surrounding the base of the shell wall.
Amphibalanus is a genus of barnacle of the family Balanidae that includes species formerly assigned to Balanus. It contains the following species:
Media related to Amphibalanus improvisus at Wikimedia Commons| Authority control databases: National |
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