| Balanus crenatus | |
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| Species: | B. crenatus |
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| Balanus crenatus Bruguière, 1789 | |
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Balanus crenatus is a species of acorn barnacle in the Balanidae family. It is found in the North Pacific and the North Atlantic Ocean.
The shell of B. crenatus is made of six calcareous plates and grows up to 25 millimetres (0.98 in) across. The upper edge of the plates are toothed and the shell is often tilted to one side. The opercular aperture is diamond shaped and protected by two further plates which can slide across when the animal is not feeding. [2]
This is a boreal species distributed in intertidal and sublittoral zones of the North Pacific and the North Atlantic. It has a similar distribution to Balanus balanus , a species with which it is often associated. [3]
This barnacle is a hermaphrodite and the reproductive organs develop during the winter. Individuals in a group fertilise each other and, after a period of maturation, nauplii are liberated into the water. After a number of moults, the larvae settle out of the zooplankton in about April and attach themselves to rocks and stones on the sea floor. B. crenatus is a fast-growing barnacle and can grow from a length of 3 millimetres (0.12 in) to 9 mm (0.35 in) in the month of May after settling. It is fully grown by August and ready to reproduce in its first winter. [4]
This species is mainly found in the sublittoral zone but can sometimes be found under stones or overhangs on the lower shore. It colonises pebbles, bedrock, shells and artificial structures. It is found in both calm and exposed waters and can tolerate low salinity levels [2] and is found at depths of up to 60 metres (200 ft). It seems to favour habitats with strong currents and when overcrowding occurs, may be distorted to fit the space available. It is often found growing alongside another species of barnacle, Balanus balanus . [4]
The main predator is the juvenile common starfish (Asterias rubens). Medium sized barnacles seem to be at greatest risk. Small specimens are ignored while large specimens seem able to withstand attack but in some years, the population is decimated. [5]
Balanus is a genus of barnacles in the family Balanidae of the subphylum Crustacea.
Acorn barnacles are one of the most common barnacle species on the Pacific coast of North America, distributed from the U.S. state of Alaska to Bahía de San Quintín near San Quintín, Baja California. They are commonly found in the upper intertidal zone on mussels, rocks and pier pilings. They can obtain oxygen from both water and air.
Austrominius modestus is a species of barnacle in the family Austrobalanidae, 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 (0.39 in) in diameter.
Acorn barnacle and acorn shell are vernacular names for certain types of stalkless barnacles, generally excluding Pedunculata. Depending on region and author, they could mean any of the following taxa:
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.
The common starfish, common sea star or sugar starfish is the most common and familiar starfish in the north-east Atlantic. Belonging to the family Asteriidae, it has five arms and usually grows to between 10–30 cm across, although larger specimens are known. The common starfish is usually orange or brownish in color, and sometimes violet; specimens found in deeper waters are pale. The common starfish is found on rocky and gravelly substrates where it feeds on mollusks and other benthic invertebrates.
Whale barnacles are species of acorn barnacle that belong to the subfamily Coronulinae, family Coronulidae. They typically attach to baleen whales, and sometimes settle on toothed whales. The whale barnacles diverged from the turtle barnacles about three million years ago.
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.
Amphibalanus improvisus, the bay barnacle, is a species of acorn barnacle in the family Balanidae.
Chlamys hastata, the spear scallop, spiny scallop or swimming scallop, is a species of bivalve mollusc in the family Pectinidae found on the west coast of North America from the Gulf of Alaska to San Diego, California. A limited number of these scallops are harvested by divers or by narrow trawls off the west coast of Canada.
Novocrania anomala is a species of brachiopod found offshore in the eastern Atlantic Ocean.
Balanus balanus is a species of acorn barnacle in the Balanidae family. It is native to the colder seas of the northern hemisphere.
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.
Ophiocomina nigra, commonly known as the black brittle star or black serpent star, is a species of marine invertebrate in the order Ophiurida. It occurs in the north-eastern Atlantic Ocean, the North Sea and the Mediterranean Sea.
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.
Asterias forbesi, commonly known as Forbes sea star, is a species of starfish in the family Asteriidae. It is found in shallow waters in the northwest Atlantic Ocean and the Caribbean Sea.
Amphibalanus eburneus, the ivory 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.
Semibalanus cariosus, commonly known as the thatched barnacle, rock barnacle or horse barnacle, is a species of acorn barnacle occurring in the northern Pacific Ocean.