43-480: Lithacrosiphon is a genus of worms belonging to the family Aspidosiphonidae . The species of this genus are found in all world oceans. Species: L. cristatus was redescribed and included the formerly distinct species L. altriconus , L. gurjanovae , L. indicus , and L. odhneri . L. uniscutatus was redescribed and included L. kukenthali and L. poritidis . Worm Worms are many different distantly related bilateral animals that typically have
86-587: A backbone) such as blindworms and caecilians . Worms include several groups. The three main phyla are: Familiar worms include the earthworms , members of phylum Annelida . Other invertebrate groups may be called worms, especially colloquially. In particular, many unrelated insect larvae are called "worms", such as the railroad worm , woodworm , glowworm , bloodworm , butterworm , inchworm , mealworm , silkworm , and woolly bear worm . Worms may also be called helminths , particularly in medical terminology when referring to parasitic worms , especially
129-463: A few fungi, a few species of trematodes , and a parasitic castrator isopod , Hemioniscus balani . Barnacles were classified by Linnaeus and Cuvier as Mollusca , but in 1830 John Vaughan Thompson published observations showing the metamorphosis of the nauplius and cypris larvae into adult barnacles, and noted that these larvae were similar to those of crustaceans. In 1834, Hermann Burmeister reinterpreted these findings, moving barnacles from
172-460: A long cylindrical tube-like body, no limbs , and usually no eyes . Worms vary in size from microscopic to over 1 metre (3.3 ft) in length for marine polychaete worms (bristle worms); 6.7 metres (22 ft) for the African giant earthworm, Microchaetus rappi ; and 58 metres (190 ft) for the marine nemertean worm (bootlace worm), Lineus longissimus . Various types of worm occupy
215-458: A mollusc, or a ship; or to an animal such as a whale ( whale barnacles ). The most common form, acorn barnacles , are sessile , growing their shells directly onto the substrate, whereas goose barnacles attach themselves by means of a stalk. Barnacles have a carapace made of six hard calcareous plates, with a lid or operculum made of four more plates. Inside the carapace, the animal lies on its stomach, projecting its limbs downwards. Segmentation
258-572: A pejorative epithet to describe a cowardly, weak or pitiable person. Worms can also be farmed for the production of nutrient-rich vermicompost . Cirripede Barnacles are arthropods of the subclass Cirripedia in the subphylum Crustacea . They are related to crabs and lobsters , with similar nauplius larvae . Barnacles are exclusively marine invertebrates ; many species live in shallow and tidal waters. Some 2,100 species have been described. Barnacle adults are sessile ; most are suspension feeders with hard calcareous shells, but
301-404: A pulling strength of 5,000 lbf/in (30,000 kPa) and a sticking strength of 22–60 lbf/in (200–400 kPa). Barnacles have no true heart , although a sinus close to the esophagus performs a 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
344-430: A quarter of individuals with a close neighbour. This 2013 discovery overturned the long-held belief that barnacles were limited to pseucocopulation or hermaphroditism. Rhizocephalan barnacles had been considered hermaphroditic, but their males inject themselves into females' bodies, degrading to little more than sperm-producing cells. Most barnacles are filter feeders. From within their shell, they repeatedly reach into
387-428: A rafting lifestyle, drifting around close to the water's surface. They colonize every floating object, such as driftwood, and like some non-stalked barnacles attach themselves to marine animals. The species most specialized for this lifestyle is Dosima fascicularis , which secretes a gas-filled cement that makes it float at the surface. Other members of the class have an entirely different mode of life. Barnacles of
430-429: A small variety of parasitic niches, living inside the bodies of other animals. Free-living worm species do not live on land but instead live in marine or freshwater environments or underground by burrowing. In biology, "worm" refers to an obsolete taxon , Vermes , used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non- arthropod invertebrate animals , now seen to be paraphyletic . The name stems from
473-421: A thorax or abdomen. This undergoes six moults, 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 . All but the first instars are filter feeders. The cypris larva is the second and final larval stage before adulthood. In Rhizocephala and Thoracica an abdomen
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#1732783297351516-589: Is Praelepas from the mid- Carboniferous , around 330-320 million years ago. Older claimed barnacles such as Priscansermarinus from the Middle Cambrian , some 510 to 500 million years ago , do not show clear barnacle morphological traits, though Rhamphoverritor from the Silurian Coalbrookdale Formation of England may represent a stem-group barnacle. Barnacles first radiated and became diverse during
559-536: Is absent in this stage, but the y-cyprids (post-naupliar instar) has three distinct abdominal segments. It is not a feeding stage; its role is to find a suitable place to settle, since the adults are sessile . The cyprid stage lasts from days to weeks. It explores potential surfaces with modified antennules ; once it has found a suitable spot, it attaches head-first using its antennules and a secreted glycoproteinous cement. Larvae assess surfaces based upon their surface texture, chemistry, relative wettability, color, and
602-466: Is attested in the early 13th century as Middle English "bernekke" or "bernake", close to Old French "bernaque" and medieval Latin bernacae or berneka , denoting the barnacle goose . Because the full life cycles of both barnacles and geese were unknown at the time, (geese spend their breeding seasons in the Arctic) a folktale emerged that geese hatched from barnacles. It was not applied strictly to
645-488: Is fished, or overfished, in commercial quantities on the Chilean coast, where it is known as the picoroco . MIT researchers have developed an adhesive inspired by the protein-based bioglue produced by barnacles to firmly attach to rocks. The adhesive can form a tight seal to halt bleeding within about 15 seconds of application. The stable isotope signals in the layers of barnacle shells can potentially be used as
688-669: Is not a worm at all, but a skin fungus. Lobopodians are an informal grouping of extinct panarthropods from the Cambrian to the Carboniferous that are often called worms or "worm-like animals" despite having had legs in the form of stubby lobopods. Likewise, the extant Onychophora are sometimes called velvet worms despite possessing stubby legs. Wyrm was the Old English term for carnivorous reptiles ("serpents") and mythical dragons . "Worm" has also been used as
731-459: Is sometimes used to refer to parasitic worms. The term is more commonly used in medicine , and usually refers to roundworms and tapeworms. In taxonomy, "worm" refers to an obsolete grouping, Vermes , used by Carl Linnaeus and Jean-Baptiste Lamarck for all non- arthropod invertebrate animals , now seen to be polyphyletic . In 1758, Linnaeus created the first hierarchical classification in his Systema Naturae . In his original scheme,
774-425: Is usually indistinct; the body is more or less evenly divided between the head and thorax , with little or no abdomen . Adult barnacles have few appendages on their heads, with only a single, vestigial pair of antennae attached to the cement gland. The six pairs of thoracic limbs are called cirri ; these are feathery and very long. The cirri extend to filter food, such as plankton , from the water and move it towards
817-531: The Mollusca to Articulata (in modern terms, annelids + arthropods), showing naturalists that detailed study was needed to reevaluate their taxonomy. Charles Darwin took up this challenge in 1846, and developed his initial interest into a major study published as a series of monographs in 1851 and 1854. He undertook this study at the suggestion of his friend the botanist Joseph Dalton Hooker , namely to thoroughly understand at least one species before making
860-467: The Nematoda (roundworms) and Cestoda (tapeworms). Hence, " helminthology " is the study of parasitic worms. When a human or an animal, such as a dog or horse, is said to "have worms", it means that it is infested with parasitic worms , typically roundworms or tapeworms . Deworming is a method to kill off the worms that have infected a human or animal by giving anthelmintic drugs. " Ringworm "
903-411: The Old English word wyrm . Most animals called "worms" are invertebrates , but the term is also used for the amphibian caecilians and the slowworm Anguis , a legless burrowing lizard . Invertebrate animals commonly called "worms" include annelids , nematodes , flatworms , nemerteans , chaetognaths , priapulids , and insect larvae such as grubs and maggots . The term " helminth "
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#1732783297351946-610: The Rhizocephala are specialized parasites of other crustaceans, with reduced bodies. Barnacles have existed since at least the mid- Carboniferous , some 325 million years ago. In folklore, barnacle geese were once held to emerge fully formed from goose barnacles . Both goose barnacles and the Chilean giant barnacle are fished and eaten. Barnacles are economically significant as biofouling on ships, where they cause hydrodynamic drag , reducing efficiency. The word "barnacle"
989-579: The mussel Mytilus edulis and the ascidian Styela gibbsi . Another predator is the starfish species Pisaster ochraceus . A stalked barnacle in the Iblomorpha, Chaetolepas calcitergum , lacks a heavily mineralised shell, but contains a high concentration of toxic bromine ; this may serve to deter predators. The turbellarian flatworm Stylochus , a serious predator of oyster spat , has been found in barnacles. Parasites of barnacles include many species of Gregarinasina ( alveolate protozoa),
1032-598: The superorder Rhizocephala , including the genus Sacculina , are parasitic castrators of other arthropods, including crabs. The anatomy of these parasitic barnacles is greatly reduced compared to their free-living relatives. They have no carapace or limbs, having only unsegmented sac-like bodies. They feed by extending thread-like rhizomes of living cells into their hosts' bodies from their points of attachment. Barnacles are displaced by limpets and mussels , which compete for space. They employ two strategies to overwhelm their competitors: "swamping", and fast growth. In
1075-549: The 13th century, worms were recognized in Europe as part of the category of reptiles that consisted of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians", as recorded by Vincent of Beauvais in his Mirror of Nature . In everyday language, the term worm is also applied to various other living forms such as larvae , insects , millipedes , centipedes , shipworms (teredo worms), or even some vertebrates (creatures with
1118-715: The Cirripedia as a full class or subclass . In 2001, Martin and Davis placed Cirripedia as an infraclass of Thecostraca , and divided it into six orders: In 2021, Chan et al. elevated Cirripedia to a subclass of the Thecostraca , and the superorders Acrothoracica, Rhizocephala, and Thoracica to infraclass. The updated classification with 11 orders has been accepted in the World Register of Marine Species . Barnacles are of economic consequence, as they often attach themselves to man-made structures. Particularly in
1161-681: The Late Cretaceous . Barnacles underwent a second, much larger radiation beginning during the Neogene and still continuing. The following cladogram , not fully resolved, shows the phylogenetic relationships of the Cirripedia within Thecostraca as of 2021. Facetotecta Laurida Dendrogastrida Cryptophialida Lithoglyptida Iblomorpha Pollicipedomorpha Calanticomorpha Scalpellomorpha Verrucomorpha Balanomorpha Rhizocephala Over 2,100 species of Cirripedia have been described. Some authorities regard
1204-551: The animals were one of three kingdoms, divided into the classes of Vermes , Insecta , Pisces , Amphibia , Aves , and Mammalia . Since then the last four have all been subsumed into a single phylum, the Chordata , while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by Lamarck, who called the Vermes une espèce de chaos (a sort of chaos) and split
1247-457: The arthropod until the 1580s. The ultimate meaning of the word is unknown. The name Cirripedia comes from the Latin words cirritus "curly" from cirrus "curl" and pedis from pes "foot". The two words together mean "curly-footed", alluding to the curved legs used in filter-feeding. Most barnacles are encrusters, attaching themselves to a hard substrate such as a rock, the shell of
1290-583: 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 moulted hermaphroditic individuals are receptive as females. Self-fertilization, although theoretically possible, has been experimentally shown to be rare in barnacles. The sessile lifestyle of acorn barnacles makes sexual reproduction difficult, as they cannot leave their shells to mate. To facilitate genetic transfer between isolated individuals, barnacles have extraordinarily long penises . Barnacles probably have
1333-510: The case of ships, they are classified as fouling organisms. The number and size of barnacles that cover ships can impair their efficiency by causing hydrodynamic drag . The flesh of some barnacles is routinely consumed by humans, including Japanese goose barnacles ( e.g. Capitulum mitella ), and goose barnacles ( e.g. Pollicipes pollicipes ), a delicacy in Spain and Portugal . The Chilean giant barnacle Austromegabalanus psittacus
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1376-487: The chthalamoids in the Oligocene, when they evolved tubular skeletons, which provide better anchorage to the substrate, and allow them to grow faster, undercutting, crushing, and smothering chthalamoids. Among the most common predators of barnacles are whelks . They are able to grind through the calcareous exoskeleton and eat the animal inside. Barnacle larvae are consumed by filter-feeding benthic predators including
1419-422: The cirri and the surface of the body. 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 has three photoreceptors (ocelli), one median and two lateral. These record the stimulus for the barnacle shadow reflex, where a sudden decrease in light causes cessation of the fishing rhythm and closing of
1462-444: The exact height of an assemblage above or below sea level to be precisely determined. Since the intertidal zone periodically desiccates , barnacles are well adapted against water loss. Their calcite shells are impermeable, and they can close their apertures with movable plates when not feeding. Their hard shells are assumed by zoologists to have evolved as an anti-predator adaptation . One group of stalked barnacles has adapted to
1505-451: The generalisations needed for his theory of evolution by natural selection . The Royal Society notes that barnacles occupied Darwin, who worked from home, so intensely "that his son assumed all fathers behaved the same way: when visiting a friend he asked, 'Where does your father do his barnacles?'" Upon the conclusion of his research, Darwin declared "I hate a barnacle as no man ever did before." The oldest definitive fossil barnacle
1548-442: The group into three new phyla, worms, echinoderms, and polyps (which contained corals and jellyfish). By 1809, in his Philosophie Zoologique , Lamarck had created 9 phyla apart from vertebrates (where he still had 4 phyla: mammals, birds, reptiles, and fish) and molluscs, namely cirripedes , annelids, crustaceans, arachnids, insects, worms, radiates , polyps, and infusorians . Chordates are remarkably wormlike by ancestry. In
1591-482: The largest penis-to-body size ratio of the animal kingdom, up to eight times their body length, though on exposed coasts the penis is shorter and thicker. The mating of acorn barnacles is described as pseudocopulation. The goose barnacle Pollicipes polymerus can alternatively reproduce by spermcasting, in which the male barnacle releases his sperm into the water, to be taken up by females. Isolated individuals always made use of spermcasting and sperm capture, as did
1634-517: The mouth. Acorn 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. These glands secrete a type of natural quick cement made of complex protein bonds (polyproteins) and other trace components like calcium . This natural cement can withstand
1677-424: The opercular plates. The photoreceptors are likely only capable of sensing the difference between light and dark. This eye is derived from the primary naupliar eye . Barnacles pass through two distinct larval stages, the nauplius and the cyprid, before developing into a mature adult. A fertilised egg hatches into a nauplius: a one-eyed larva comprising a head and a telson with three pairs of limbs, lacking
1720-474: The presence or absence and composition of a surface biofilm ; swarming species are more likely to attach near other barnacles. As the larva exhausts its energy reserves, it becomes less selective in the sites it selects. It cements itself permanently to the substrate with another proteinaceous compound, and then undergoes metamorphosis into a juvenile barnacle. Typical acorn barnacles develop six hard calcareous plates to surround and protect their bodies. For
1763-544: The rest of their lives, they are cemented to the substrate, using their feathery legs (cirri) to capture plankton. Once metamorphosis is over and they have reached their adult form, barnacles continue to grow by adding new material to their heavily calcified plates. These plates are not moulted ; however, like all ecdysozoans , the barnacle moults its cuticle . Most barnacles are hermaphroditic , producing both eggs and sperms. A few species have separate sexes , or have both males and hermaphrodites . The ovaries are located in
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1806-543: 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. 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. Competitors may include other barnacles. Balanoids gained their advantage over
1849-498: The water column with their cirri. These feathery appendages beat rhythmically to draw plankton and detritus into the shell for consumption. Although they have been found at water depths to 600 m (2,000 ft), most barnacles inhabit shallow waters, with 75% of species living in water depths less than 100 m (300 ft), and 25% inhabiting the intertidal zone . Within the intertidal zone, different species of barnacles live in very tightly constrained locations, allowing
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