barnacle
American Heritage Dictionary:
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bar·na·cle
(bär'nə-kəl) 
n.
n.
- Any of various marine crustaceans of the subclass Cirripedia that in the adult stage form a hard shell and remain attached to submerged surfaces, such as rocks and ships' bottoms.
- The barnacle goose.
[Middle English, barnacle goose, from Old French bernacle, from Medieval Latin bernacula, diminutive of bernaca, perhaps from Old Irish báirneach, limpet.]
barnacled bar'na·cled adj.WORD HISTORY The word barnacle is known from as far back as the early 13th century. At that time it did not refer to the crustacean, as it does nowadays, but rather to a species of waterfowl presently known as the barnacle goose; more than 300 years went by before barnacle was used to refer to the crustacean. One might well wonder what the connection between these two creatures is. The answer lies in natural history. Until fairly recent times, it was widely believed that certain animals were engendered spontaneously from particular substances. Maggots, for instance, were believed to be generated from rotting meat. The barnacle goose breeds in the Arctic, a fact not known for a long time; since no one ever witnessed the bird breeding, it was thought to be spontaneously generated from trees along the shore, or from rotting wood. Wood that has been in the ocean for any length of time is often dotted with barnacles, and it was natural for people to believe that the crustaceans were also engendered directly from the wood, like the geese. In fact, as different as the two creatures might appear to us, they share a similar trait: barnacles have long feathery cirri that are reminiscent of a bird's plumage. This led one writer in 1678 to comment on the "multitudes of little Shells; having within them little Birds perfectly shap'd, supposed to be Barnacles [that is, barnacle geese]." In popular conception the two creatures were thus closely linked. Over time the crustacean became the central referent of the word, and the bird was called the barnacle goose for clarity, making barnacle goose an early example of what we now call a retronym.
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barnacle
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Barnacle (credit: Anthony Mercieca/Root Resources)
Barnacle (credit: Anthony Mercieca/Root Resources)
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The name popularly applied to two types of Crustacea, subclass Cirripedia, the goose barnacles and acorn barnacles. Both were formerly of importance to seafarers (and acorn barnacles are still so) because of their habit of adhering to ships hulls. Four orders of barnacles are recognized, of which one only, the Thoracica, fits the popular conception of barnacles. See also Cirripedia.
Columbia Encyclopedia:
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Barnacle
barnacle, common name of the sedentary crustacean animals constituting the infraclass Cirripedia. Barnacles are exclusively marine and are quite unlike any other crustacean because of the permanently attached, or sessile, mode of existence for which they are highly modified. Typical barnacles attach to the substrate by means of an exceedingly adhesive cement, produced by a cement gland, and secrete a shell, or carapace, of calcareous (limestone) plates, around themselves. Colonies of such barnacles form conspicuous encrustations on wharves, boats, pilings, and rocky shores. They range in length from under 1 in. (2.5 cm) to 30 in. (75 cm). Their shells are commonly yellow, orange, red, pink, or purple, sometimes with striped patterns. Because of their sedentary life and enclosing shells, barnacles were thought to be mollusks until 1830, when their larval stages were discovered. Much of what is known about barnacles is the result of research by Charles Darwin, who published a monumental work on the subject in the 1840s.
Shelled and Shell-less Barnacles
Barnacles with a calcareous shell (order Thoracica) include the gooseneck barnacles, which are attached to the substrate by means of a stalk, or peduncle, and the acorn, or rock, barnacles, which are attached directly to the substrate. The stalk of gooseneck barnacles is simply an elongation of the attached end of the animal's body. In some gooseneck barnacles the stalk as well as the body is covered by calcareous plates; in others it is a naked leathery or horny structure. A gooseneck barnacle found in large numbers on ships and pilings is Lepas, which has a leathery stalk and flattened shell and looks like a small clam attached by its siphon.
Balanus is an acorn barnacle commonly found on rocks; it has a thick conical shell attached at its wide base, with an opening at the top. As in many of the acorn barnacles, the plates of the surrounding carapace form an impenetrable wall, and the opening is equipped with two movable plates that can be pulled down to close off the body completely.
In both gooseneck and acorn barnacles the feathery legs of the animal may sometimes be seen protruding through the carapace opening. When the animal feeds, these jointed legs, called cirri, sweep organic particles and minute planktonic organisms toward the mouth, which is located deeper inside the shell. The attached end of the animal is its anterior, or head region: the barnacle has been described as a shrimplike animal standing on its head in a limestone house and kicking food into its mouth with its feet. Barnacles lack gills; gas exchange occurs through the cirri and the body wall. Some shelled barnacles are commensal, attaching themselves to living animals such as whales, porpoises, turtles, crustaceans, and echinoderms. The gooseneck barnacle Conchoderma may be found growing on the acorn barnacle Coronula, which grows on the skin of whales.
Besides the shelled barnacles there are naked barnacles (orders Ascothoracica and Rhizocephala), which live on, and in some cases parasitize, other invertebrate animals. There are also shell-less boring barnacles (order Acrothoracica), which live inside holes that they drill in shells and corals.
Reproduction
Although nearly all other crustaceans have separate sexes, most barnacles are hermaphrodites, with cross-fertilization between adjacent individuals being the rule. Some species, however, have dwarf males, which are parasitic on female or hermaphroditic individuals. The fertilized egg develops into a free-swimming larva, called a nauplius larva, of the basic crustacean type, with paired antennae. This form then molts to become a cypris, or bivalve, larva, which eventually attaches itself to a suitable substrate by its first pair of antennae and undergoes metamorphosis into an adult.
Economic Significance
Barnacles are economically significant because they settle on ship hulls and harbor installations; the resulting encrustation of the ships greatly increases friction, diminishing speed and increasing fuel consumption. Ships are treated with plastic coating or with antifouling paints containing copper or mercury to prevent or diminish encrustation.
Classification
Barnacles are classified in the phylum Arthropoda, subphylum Crustacea, class Maxillopoda, infraclass Cirripedia.
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Warwickshire Bernhangre (1086) (DB). ‘Wooded slope by a barn’. OE bere-ærn + hangra.
| Barnack, Barna, Barmston | |
| Barnacullia, Barnaderg, Barnageeha |
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barnacled
IN BRIEF: adj. - Covered with marine crustaceans
The ship's hull was barnacled.
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Saunders Veterinary Dictionary:
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barnacle
An adult cirripede that lives attached to fixed objects; an aquatic member of the subclass Cirrepedia of the class Crustacea.
Random House Word Menu:
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categories related to 'barnacle'
See crossword solutions for the clue Wikipedia on Answers.com:
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Barnacle
For other uses, see Barnacle (disambiguation).
| Barnacles Temporal range: Mid Cambrian–Recent |
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| "Cirripedia" from Ernst Haeckel's Kunstformen der Natur (1904). The crab at the centre is nursing the externa of the parasitic cirripede Sacculina | |
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| Chthamalus stellatus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Maxillopoda |
| Subclass: | Thecostraca |
| Infraclass: | Cirripedia Burmeister, 1834 |
| Superorders | |
| Synonyms | |
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Thyrostraca, Cirrhopoda (meaning "curl-footed"), Cirrhipoda, and Cirrhipedia. |
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A barnacle is a type of arthropod belonging to infraclass 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 settings. They are sessile (non-motile) suspension feeders, and have two nektonic (active swimming) larval stages. Around 1,220 barnacle species are currently known.[1] The name "Cirripedia" is Latin, meaning "curl-footed".
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Contents
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Ecology
Semibalanus balanoides feeding (also available at higher resolution)
Barnacles are encrusters, attaching themselves permanently to a hard substrate. The most common, "acorn barnacles" (Sessilia), are sessile, growing their shells directly onto the substrate.[2] The order Pedunculata ("goose barnacles" and others) attach themselves by means of a stalk.[2]
Most barnacles are suspension feeders; they dwell continually in their shell – which is usually constructed of six plates[2] – and reach into the water column with modified legs. These feathery appendages beat rhythmically to draw plankton and detritus into the shell for consumption.[3]
Other members of the class have quite a different mode of life. For example, members of the genus Sacculina are parasitic, dwelling within crabs.[4]
Although they have been found at water depths up to 600 m (2,000 ft),[2] most barnacles inhabit shallow waters, with 75% of species living in water depths of less than 100 m (300 ft),[2] and 25% inhabiting the intertidal zone.[2] Within the intertidal zone, different species of barnacle live in very tightly constrained locations, allowing the exact height of an assemblage above or below sea level to be precisely determined.[2]
Since the intertidal zone periodically desiccates, barnacles are well adapted against water loss. Their calcite shells are impermeable, and they possess two plates which they can slide across their aperture when not feeding. These plates also protect against predation.[5]
Barnacles are displaced by limpets and mussels, which compete for space. They also have numerous predators.[2] They employ two strategies to overwhelm their competitors: "swamping" and fast growth. In the swamping strategy, vast numbers of barnacles settle in the same place at once, covering a large patch of substrate, allowing at least some to survive in the balance of probabilities.[2] Fast growth allows the suspension feeders to access higher levels of the water column than their competitors, and to be large enough to resist displacement; species employing this response, such as the aptly named Megabalanus, can reach 7 cm (3 in) in length;[2] other species may grow larger still (Austromegabalanus psittacus).
Competitors may include other barnacles, and there is (disputed) evidence that balanoid barnacles competitively displaced chthalamoid barnacles. Balanoids gained their advantage over the chthalamoids in the Oligocene, when they evolved a tubular skeleton. This provides better anchorage to the substrate, and allows them to grow faster, undercutting, crushing and smothering the latter group.[6]
Among the most common predators on barnacles are whelks. They are able to grind through the calcareous exoskeletons of barnacles and feed on the softer inside parts. Mussels also prey on barnacle larvae.[7] Another predator on barnacles is the starfish species Pisaster ochraceus.[8][9]
Adult anatomy
Free-living barnacles are attached to the substratum by cement glands that form the base of the first pair of antennae; in effect, the animal is fixed upside down by means of its forehead. In some barnacles, the cement glands are fixed to a long muscular stalk, but in most they are part of a flat membrane or calcified plate. A ring of plates surrounds the body, homologous with the carapace of other crustaceans. These consist of the rostrum, two lateral plates, two carino-laterals and a carina.[10] In sessile barnacles, the apex of the ring of plates is covered by an operculum, which may be recessed into the carapace. The plates are held together by various means, depending on species, in some cases being solidly fused.
Inside the carapace, the animal lies on its back, with its limbs projecting upwards. Segmentation is usually indistinct, and the body is more or less evenly divided between the head and thorax, with little, if any, abdomen. Adult barnacles have few appendages on the head, with only a single, vestigial, pair of antennae, attached to the cement gland. There are six pairs of thoracic limbs, referred to as "cirri", which are feathery and very long, being used to filter food from the water and move it towards the mouth.
Barnacles have no true heart, although a sinus close to the oesophagus performs similar function, with blood being pumped through it by a series of muscles. The blood vascular system is minimal. Similarly, they have no gills, absorbing oxygen from the water through their limbs and the inner membrane of the carapace. The excretory organs of barnacles are maxillary glands.
The main sense of barnacles appears to be touch, with the hairs on the limbs being especially sensitive. The adult also has a single eye, although this is probably only capable of sensing the difference between light and dark.[11] This eye is derived from the primary naupliar eye.[12]
Parasitic barnacles
The anatomy of parasitic barnacles is generally simpler than that of their free-living relatives. They have no carapace or limbs, having only an unsegmented sac-like body. Such barnacles feed by extending thread-like rhizomes of living cells into the host's body from their point of attachment.[11]
Life cycle
Barnacles have two distinct larval stages, the nauplius and the cyprid, before developing into a mature adult.
Nauplius
A fertilised egg hatches into a nauplius: a one-eyed larva comprising a head and a telson, without a thorax or abdomen. This undergoes 6 months of growth, passing through five instars, before transforming into the cyprid stage. Nauplii are typically initially brooded by the parent, and released after the first moult as larvae that swim freely using setae.[13]
Cyprid
The cyprid larva is the last larval stage before adulthood. It is a non-feeding stage whose role is to find a suitable place to settle, since the adults are sessile.[13] The cyprid stage lasts from days to weeks. It explores potential surfaces with modified antennules; once it has found a potentially suitable spot, it attaches head-first using its antennules, and a secreted glycoproteinous substance. Larvae are thought to assess surfaces based upon their surface texture, chemistry, relative wettability, colour and the presence/absence and composition of a surface biofilm; swarming species are also more likely to attach near to other barnacles.[14] As the larva exhausts its finite energy reserves, it becomes less selective in the sites it selects. It cements itself permanently to the substrate with another proteinacous compound, and then undergoes metamorphosis into a juvenile barnacle.[14]
Adult
Typical acorn barnacles develop six hard calcareous plates to surround and protect their bodies. For the rest of their lives they are cemented to the ground, using their feathery legs (cirri) to capture plankton.
Once metamorphosis is over and they have reached their adult form, barnacles will continue to grow by adding new material to their heavily calcified plates. These plates are not moulted; however, like all ecdysozoans, the barnacle itself will still molt its cuticle.[15]
Sexual reproduction
Most barnacles are hermaphroditic, although a few species are gonochoric or androdioecious. The ovaries are located in the base or stalk, and may extend into the mantle, while the testes are towards the back of the head, often extending into the thorax. Typically, recently molted hermaphroditic individuals are receptive as females. Self-fertilization, although theoretically possible, has been experimentally shown to be rare in barnacles.[16][17]
The sessile lifestyle of barnacles makes sexual reproduction difficult, as the organisms cannot leave their shells to mate. To facilitate genetic transfer between isolated individuals, barnacles have extraordinarily long penises. Barnacles probably have the largest penis to body size ratio of the animal kingdom.[16]
Fossil record
The geological history of barnacles can be traced back to animals such as Priscansermarinus from the Middle Cambrian (on the order of 510 to 500 million years ago),[18] although they do not become common as skeletal remains in the fossil record until the Neogene (last 20 million years).[2] In part their poor skeletal preservation is due to their restriction to high-energy environments, which tend to be erosional – therefore it is more common for their shells to be ground up by wave action than for them to reach a depositional setting. Trace fossils of acrothoracican barnacle borings (Rogerella) are common in the fossil record from the Devonian to the Recent.
Barnacles can play an important role in estimating palæo-water depths. The degree of disarticluation of fossils suggests the distance they have been transported, and since many species have narrow ranges of water depths, it can be assumed that the animals lived in shallow water and broke up as they were washed down-slope. The completeness of fossils, and nature of damage, can thus be used to constrain the tectonic history of regions.[2]
In human culture
Barnacles were first fully studied and classified by Charles Darwin who published a series of monographs in 1851 and 1854. Darwin undertook this study at the suggestion of his friend Joseph Dalton Hooker, in order to thoroughly understand at least one species before making the generalisations needed for his theory of evolution by natural selection.[19] In her 2003 book Darwin and the Barnacle, historian of science and novelist Rebecca Stott challenged the supposition that Darwin was using the barnacle project as a way of delaying writing the book which would become On the Origin of Species.[20]
Barnacles are of economic consequence as they often attach themselves to man-made structures, sometimes to the structure's detriment. Particularly in the case of ships, they are classified as fouling organisms.[21]
Some barnacles are considered edible by humans, and goose barnacles (e.g. Pollicipes pollicipes), in particular, are a delicacy in Spain and Portugal.[22] The resemblance of this barnacle's fleshy stalk to a goose's neck gave rise in ancient times to the notion that geese, or at least certain seagoing species of wild goose, literally grew from the barnacle. Indeed, the word "barnacle" originally referred to a species of goose, the Barnacle goose Branta leucopsis, whose eggs and young were rarely seen by humans because it breeds in the remote Arctic.[23]
The picoroco barnacle is used in Chilean cuisine and is one of the ingredients in curanto.
Classification
Some authorities regard Cirripedia as a full class or subclass, and the orders listed above are sometimes treated as superorders. In 2001, Martin and Davis placed Cirripedia as an infraclass of Thecostraca and divided it into six orders:[24]
Infraclass Cirripedia Burmeister, 1834
- Superorder Acrothoracica Gruvel, 1905
- Order Pygophora Berndt, 1907
- Order Apygophora Berndt, 1907
- Superorder Rhizocephala Müller, 1862
- Order Kentrogonida Delage, 1884
- Order Akentrogonida Häfele, 1911
- Superorder Thoracica Darwin, 1854
- Order Pedunculata Lamarck, 1818
- Order Sessilia Lamarck, 1818
References
- ^ Martin Walters & Jinny Johnson (2007). The World of Animals. Bath, Somerset: Parragon. ISBN 1-4054-9926-5.
- ^ a b c d e f g h i j k l P. Doyle, A. E. Mather, M. R. Bennett & A. Bussell (1997). "Miocene barnacle assemblages from southern Spain and their palaeoenvironmental significance". Lethaia 29 (3): 267–274. doi:10.1111/j.1502-3931.1996.tb01659.x.
- ^ "Shore life". Encarta Encyclopedia 2005 DVD.
- ^ Carl Zimmer (2000). Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures. Free Press. ISBN 0-7432-0011-X.
- ^ Stacy E. Leone (2008). Predator induced plasticity in barnacle shell morphology (Master of Arts in Biology thesis). New Britain, Connecticut: Central Connecticut State University. http://eprints.ccsu.edu/archive/00000496/03/1952FT.pdf.
- ^ S. M. Stanley (2008). "Predation defeats competition on the seafloor". Paleobiology 34 (1): 1–21. doi:10.1666/07026.1. http://www.bioone.org/perlserv/?request=get-document&doi=10.1666%2F07026.1.
- ^ Clint Twist (2005). Visual Factfinder: Oceans. Great Bardfield, Essex: Miles Kelly Publishing.
- ^ C. D. G. Harley, M. S. Pankey, J. P. Wares, R. K. Grosberg, M. J. Wonham (2006). "Color Polymorphism and Genetic Structure in the Sea Star Pisaster ochraceus". The Biological Bulletin 211 (3): 248–262. doi:10.2307/4134547. JSTOR 4134547. PMID 17179384. http://www.biolbull.org/cgi/content/full/211/3/248.
- ^ Jan Holmes (2002). "Seashore players most successful when they're in their zone". WSU Beach Watchers. http://www.beachwatchers.wsu.edu/island/essays/zonation.htm. Retrieved March 6, 2010.
- ^ Let's learn about the body structure of a barnacle Retrieved 2011-11-28.
- ^ a b Robert D. Barnes (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 694–707. ISBN 0-03-056747-5.
- ^ Thursten C. Lacalli (2009). "Serial EM analysis of a copepod larval nervous system". Arthropod Structure & Development 38 (5): 361–75. doi:10.1016/j.asd.2009.04.002. PMID 19376268.
- ^ a b William A. Newman (2007). "Cirripedia". In Sol Felty Light & James T. Carlton. The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon (4th ed.). University of California Press. pp. 475–484. ISBN 978-0-520-23939-5.
- ^ a b Donald Thomas Anderson (1994). "Larval development and metamorphosis". Barnacles: Structure, Function, Development and Evolution. Springer. pp. 197–246. ISBN 978-0-412-44420-3. http://books.google.co.uk/books?id=2MDH9IRDkdkC&pg=PA219.
- ^ E. Bourget (1987). "Barnacle shells: composition, structure, and growth". pp. 267–285. In A. J. Southward (ed.), 1987.
- ^ a b "Biology of Barnacles". Museum Victoria. 1996. Archived from the original on February 17, 2007. http://web.archive.org/web/20070217160059/http://www.museum.vic.gov.au/crust/barnbiol.html. Retrieved April 20, 2012.
- ^ E. L. Charnov (1987). "Sexuality and hermaphroditism in barnacles: A natural selection approach". pp. 89–104. In A. J. Southward (ed.), 1987.
- ^ B. A. Foster & J. S. Buckeridge (1987). "Barnacle palaeontology". pp. 41–63. In A. J. Southward (ed.), 1987.
- ^ Étienne Benson. "Charles Darwin". SparkNotes. http://www.sparknotes.com/biography/darwin/section9.rhtml. Retrieved August 30, 2007.
- ^ Rebecca Stott (2003). Darwin and the Barnacle. W. W. Norton. ISBN 978-0-393-05745-4.
- ^ "Newcastle University Biofouling Group". Newcastle University. http://www.ncl.ac.uk/barnacles/Site/Home_page.html. Retrieved January 15, 2010.
- ^ J. Molares & J. Freire. "Fisheries and management of the goose barnacle Pollicipes pollicipes of Galicia (NW Spain)". http://www.recursosmarinos.net/wp-content/plugins/wp-publications-archive/openfile.php?action=open&file=54. Retrieved January 15, 2010.
- ^ "...all the evidence shows that the name was originally applied to the bird which had the marvellous origin, not to the shell..." Oxford English Dictionary, 2nd Edition, 1989
- ^ Joel W. Martin & George E. Davis (2001) (PDF). An Updated Classification of the Recent Crustacea. Natural History Museum of Los Angeles County. http://atiniui.nhm.org/pdfs/3839/3839.pdf.
Bibliography
- Alan J. Southward, ed. Barnacle Biology. Crustacean Issues. 5. Leiden, Netherlands: CRC Press / A. A. Balkema. ISBN 978-90-6191-628-4.
External links
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Wikimedia Commons has media related to: Cirripedia |
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Wikispecies has information related to: Cirripedia |
- Barnacles from the Marine Education Society of Australasia
- Barnacles in Spain Article on barnacles in Spain, and their collection and gastronomy.
- Darwin, C. R. (1852). The Lepadidæ. A monograph of the sub-class Cirripedia, with figures of all the species. 1. London: Ray Society. http://darwin-online.org.uk/content/frameset?itemID=F339.1&viewtype=side&pageseq=1.
- Darwin, C. R. (1854). The Balanidæ, (or sessile cirripedes); the Verrucidæ, etc.. A monograph of the sub-class Cirripedia, with figures of all the species. 2. London: Ray Society. http://darwin-online.org.uk/content/frameset?itemID=F339.2&viewtype=text&pageseq=1.
William Thomas Calman (1911). "Barnacle". In Chisholm, Hugh. Encyclopædia Britannica (11th ed.). Cambridge University Press.
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Translations:
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Barnacle
Dansk (Danish)
n. - terrier, burre
Nederlands (Dutch)
eendenmossel, iemand die je steeds aanklampt
Français (French)
n. - bernache, anatife, crampon (péj, fam), vieux loup de mer (vulg)
Deutsch (German)
n. - Rankenfüßer, "Klette"
Ελληνική (Greek)
n. - πεταλίδα, κολλιτσίδα, τσιμπούρι, αγριόχηνα
Italiano (Italian)
balano, persona attaccaticcia
Português (Portuguese)
n. - percevejo (m), óculos (m pl), ganso (m) bravo
Русский (Russian)
морской желудь, усоногий рачок
Español (Spanish)
n. - percebe, barnacla, lapa
Svenska (Swedish)
n. - långhals, igel, kardborre
中文（简体）(Chinese (Simplified))
藤壶, 难以摆脱的人, 恋栈的人, 积习
中文（繁體）(Chinese (Traditional))
n. - 藤壺, 難以擺脫的人, 戀棧的人, 積習
한국어 (Korean)
n. - 코집게, 안경, 만각류
العربيه (Arabic)
(الاسم) صدف يلصق بالصخور و السفن
עברית (Hebrew)
n. - בע"ח הנצמד לאוניה, ספחת
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