orderliness of gastropods

Nudibranchs ( [ 2 ] ) are a group of soft-bodied marine gastropod mollusk which shed their shells after their larval stage. [ 3 ] They are noted for their often extraordinary colours and striking forms, and they have been given colorful nicknames to match, such as “ clown ”, “ marigold ”, “ brilliant ”, “ dancer ”, “ dragon ”, [ 4 ] or “ ocean rabbit ”. [ 5 ] Currently, about 3,000 valid species of nudibranchs are known. [ 6 ] The word “ sea slug ” comes from the Latin nudus “ bare ” and the Ancient Greek βράγχια ( bránkhia ) “ gills “.

Nudibranchs are often casually called ocean type slug, as they are a family of opistobranchs ( sea type slug ), within the phylum Mollusca ( mollusk ), but many sea slugs belong to several taxonomic groups which are not close related to nudibranchs. A number of these early ocean slugs, such as the photosynthetic Sacoglossa and the colorful Aglajidae, are much confused with nudibranchs .

distribution and habitat [edit ]

Janolus sp. in sp. in Anilao, the Philippines Kalinga ornata from Anilao Pier dive site, depth 5 m from Anilao Pier dive site, depth 5 megabyte Nudibranchs occur in seas worldwide, ranging from the Arctic, through moderate and tropical regions, to the southern Ocean around Antarctica. [ 6 ] [ 7 ] [ 8 ] They are about entirely restricted to salt water, although a few species are known to inhabit lower salinities in brackish water. [ 9 ] Nudibranchs live at about all depths, from the intertidal partition to depths well over 700 m ( 2,300 foot ). [ 7 ] The greatest diversity of sea slug is seen in warm, shoal reefs, although one sea slug species was discovered at a astuteness near 2,500 m ( 8,200 foot ). [ 10 ] Nudibranchs are benthic animals, found crawl over the substrate. [ 7 ] The only exceptions to this are the neustonic Glaucus sea slug, which float top down just under the ocean ‘s surface ; the oceanic sea slug Cephalopyge trematoides, which swim in the water column ; [ 11 ] [ 12 ] and Phylliroe bucephalum. [ 13 ]

anatomic description [edit ]

Resembling a strip of damp sheepskin is a slug-like body with its back covered in cigar-shaped tentacles (most of which are called cerata) Berghia stephanieae nudibranch body: Note the oral tentacles (ot), foot tentacles (ft), eye (e), sea slug body : Note the oral tentacles ( ot ), animal foot tentacles ( foot ), eye ( east ), rhinophores ( roentgen ), and cerata ( speed of light ). This species has cnidosacs ( cn ) at the cerata tips. Scale bar is 100 μm. The consistency forms of sea slug vary a great share, but because they are opisthobranchs, unlike most other gastropods, they are apparently bilaterally symmetrical externally ( but not internally ) because they have undergo secondary detorsion. In all nudibranchs, the male and female intimate openings are on the right side of the body, reflecting their asymmetrical origins. They lack a mantle cavity. Some species have deadly appendages ( cerata ) on their sides, which deter predators. Many besides have a simple gut and a mouth with a radula. [ 14 ] The eyes in nudibranchs are bare and able to discern small more than light and colored. [ 15 ] The eyes are set into the body, are about a quarter of a millimeter in diameter, and consist of a lens and five photoreceptors. [ 16 ] Nudibranchs vary in adult size from 4 to 600 millimeter ( 0.16 to 23.62 in ). The adult form is without a shell or operculum ( in shelled gastropods, the operculum is a bony or aroused home plate that can cover the open of the shell when the body is withdrawn ). In most species, there is a swim veliger larva with a coiled beat, but the beat is shed at metamorphosis when the larva transforms into the adult form. Some species have target development, and the carapace is shed before the animal emerges from the testis batch. [ 14 ] The Glaucus atlanticus is an case of a sea slug that has its cerata positioned like wings rather of on its back. The name nudibranch is appropriate, since the dorids ( infraclass Anthobranchia ) breathe through a “ naked gill ” shaped into branchial plumes in a little potato on their backs. [ 17 ] By contrast, on the spinal column of the aeolids in the clade Cladobranchia, brilliantly coloured sets of protruding organs called cerata are salute. Nudibranchs have cephalic ( head ) tentacles, which are sensitive to touch, preference, and olfactory property. club-shaped rhinophores detect odors .

defense mechanisms [edit ]

In the course of their development, sea slug have lost their shells, while developing alternative defensive structure mechanism. Some species evolved an external anatomy with textures and colours that mimicked surrounding sessile invertebrate animals ( often their prey sponges or easy corals ) to avoid predators ( camouflage ). early sea slug, as seen specially well on chromodorids, have an intensely bright and contrasting color pattern that makes them particularly blatant in their surroundings. sea slug mollusk are the most normally cited examples of aposematism in marine ecosystems, but the attest for this has been contested, [ 18 ] largely because few examples of apery are seen among species, many species are nocturnal or cryptic, and bright colours at the red end of the spectrum are quickly attenuated as a function of water depth. For example, the spanish dancer sea slug ( genus Hexabranchus ), among the largest of tropical marine slugs, potently chemically defended, and brilliantly bolshevik and white, is nocturnal and has no known mimics. [ 19 ] other studies of sea slug molluscs have concluded they are aposematically coloured, for example, the slugs of the class Phylidiidae from Indo-Pacific coral reefs. [ 20 ] Nudibranchs that feed on hydrozoids can store the hydrozoids ‘ nematocysts ( stinging cells ) in the abaxial body wall, the cerata. [ 21 ] These stolen nematocysts, called kleptocnidae, wander through the alimentary tract without harming the sea slug. once farther into the organ, the cells are assimilated by intestinal protuberances and brought to specific placements on the creature ‘s back soundbox. Nudibranchs can protect themselves from the hydrozoids and their nematocysts ; the specific mechanism is yet obscure, but special cells with large vacuoles credibly play an important function. Similarly, some nudibranchs can besides take in establish cells ( symbiotic alga from soft corals ) and reuse these to make food for themselves. The related group of sacoglossan sea slugs feed on alga and retain barely the chloroplasts for their own photosynthetic function, a process known as kleptoplasty. Nudibranchs use a variety show of chemical defences to aid in protective covering, [ 22 ] but it is not necessary for the scheme to be deadly to be effective ; in fact, good arguments exist that chemical defences should evolve to be disgusting quite than toxic. [ 23 ] Some sponge-eating sea slug digest the chemical defences from their prey sponge in their bodies, rendering themselves disgusting to predators. [ 19 ] [ 24 ] One method of chemical defense used by nudibranchs are junior-grade metabolites, which play an important function in mediating relationships among marine communities. [ 25 ] The attest that suggests the chemical compounds used by dorid nudibranchs do in fact come from dietary sponges lies in the similarities between the metabolites of prey and sea slug, respectively. Furthermore, sea slug contain a mix of mooch chemicals when they are in the presence of multiple food sources, adenine well as switch defense chemicals with a coincident deepen in diet. [ 26 ] This, however, is not the only manner for sea slug to develop chemical defences. Certain Antarctic marine species refutation mechanisms are believed to be controlled by biological factors like predation and competition, and selective pressures. [ 27 ] Certain species are able to produce their own chemicals de novo without dietary influence. attest for the different methods of chemical production comes with the characteristic uniformity of chemical constitution across drastically different environments and geographic locations found throughout de novo product species compared to the wide kind of dietary and environmentally dependent chemical writing in sequestering species. [ 28 ] Another method acting of auspices is the handout of an acid from the skin. [ 29 ] Once the specimen is physically annoy or touched by another creature, it will release the mucus mechanically .

apparent production of fathom [edit ]

In 1884, Philip Henry Gosse reported observations by “ Professor Grant ” ( possibly Robert Edmond Grant ) that two species of sea slug emit sounds that are audible to humans. [ 30 ]

Two very elegant species of Sea-slug, namely, Eolis punctata [ i.e. Facelina annulicornis ], and Tritonia arborescens [ i.e. Dendronotus frondosus ], surely produce audible sounds. Professor Grant, who first observed the matter to fact in some specimens of the latter which he was keeping in an aquarium, says of the sounds, that ‘they resemble very much the tinkle of a sword wire on the side of the jar, one stroke only been given at a clock time, and repeated at intervals of a moment or two ; when placed in a big washbasin of water the sound is much obscured, and is like that of a lookout, one stroke being repeated, as earlier, at intervals. The sound is longest and most often repeated when the Tritonia are lively and moving about, and is not heard when they are cold and without any gesticulate ; in the dark I have not observed any faint emitted at the time of the stroke ; no globule of air escapes to the surface of the water system, nor is any ripple produced on the airfoil at the moment of the stroke ; the sound, when in a glass vessel, is mellow and distinct. ‘ The Professor has kept these Tritonia alive in his room for a month, and during the whole period of their confinement they have continued to produce the sounds with identical short decrease of their original saturation. In a little apartment they are audible at the distance of twelve feet. The sounds obviously proceed from the mouth of the animal ; and at the clamant of the stroke, we observe the lips abruptly separate, as if to allow the body of water to rush into a little void formed within. As these animals are hermaphrodites, requiring reciprocal impregnation, the sounds may possibly be a entail of communication between them, or, if they are of an electric nature, they may be the means of defending from alien enemies one of the most delicate, defenseless, and beautiful Gasteropods that inhabit the abstruse .

Lifecycle [edit ]

Nudibranchs are hermaphroditic, frankincense having a set of generative organs for both sexes, but they can not fertilize themselves. [ 31 ] Mating normally takes a few minutes, and involves a dance-like courtship. Nudibranchs typically deposit their eggs within a gelatinous spiral, [ 32 ] which is frequently described as looking like a ribbon. The count of egg varies ; it can be american samoa few as just 1 or 2 eggs ( Vayssierea felis ) or deoxyadenosine monophosphate many as an estimated 25 million ( Aplysia fasciata { not a sea slug } ). The egg control toxins from sea sponges as a means of deterring predators. [ 33 ] After hatching, the infants look about identical to their adult counterparts, albeit smaller. Infants may besides have fewer cerata. The life of nudibranchs can range from a few weeks to a year, depending on the species .

Feeding and ecological role [edit ]

Pteraeolidia ianthina has adapted has adapted cerata to house symbiotic zooxanthellae obtained from its diet, which continue to photosynthesize and provide energy to the sea slug. All known nudibranchs are carnivorous. [ 31 ] Some tip on sponges, others on hydroids ( e.g. Cuthona ), [ 34 ] others on bryozoans ( phanerobranchs such as Tambja, Limacia, Plocamopherus and Triopha ), [ 35 ] and some corrode other ocean slugs or their eggs ( e.g. Favorinus ) [ 36 ] or, on some occasions, are cannibals and prey on members of their own species. other groups feed on tunicates ( e.g. Nembrotha, Goniodoris ), [ 37 ] early sea slug ( Roboastra, which are descended from tunicate-feeding species ), [ 37 ] barnacles ( e.g. Onchidoris bilamellata ), [ 38 ] and anemones ( e.g. the Aeolidiidae and other Cladobranchia ). [ 35 ] The surface-dwelling sea slug, Glaucus atlanticus, is a specialist marauder of siphonophores, such as the Portuguese serviceman o ‘ war. This predatory mollusk sucks air into its digest to keep it afloat, and using its muscular foot, it clings to the surface film. If it finds a humble victim, Glaucus simply envelops it with its capacious mouthpiece, but if the prey is a larger siphonophore, the mollusk nibbles off its fishing tentacles, the ones carrying the most potent nematocysts. Like some others of its kind, Glaucus does not digest the nematocysts ; alternatively, it uses them to defend itself by passing them from its gut to the surface of its clamber. [ 39 ]

taxonomy [edit ]

Chromodoris willani shown) breathe with the branchial plume, which projects from around their anus. Dorids ( shown ) breathe with the branchial preen, which projects from around their anus .Hermissenda crassicornis pictured) have many cerata over their back which are used for defense and respiration. Aeolids ( pictured ) have many cerata over their back which are used for defense and respiration. Nudibranchs are frequently differentiated as either dorid or aeolid. Nudibranchs are normally divided into two main kinds, dorid and aeolid ( besides spelled eolid ) sea slug : [ 40 ] [ 41 ]

  • Dorids (clade Anthobranchia, Doridacea, or Doridoidea) are recognised by having an intact digestive gland and the feather-like branchial (gill) plume, which forms a cluster on the posterior part of the body, around the anus. Fringes on the mantle do not contain any intestines.[ citation needed] Additionally, dorid nudibranchs commonly have distinct pockets, bumps, and/or mantle dermal formations, which are distortions on their skin, used to store bioactive defense chemicals.[42]
  • Aeolids (clade Cladobranchia) have cerata (spread across the back) instead of the branchial plume. The cerata function in place of gills and facilitate gas exchange through the epidermis. Additionally, aeolids possess a branched digestive gland, which may extend into the cerate and often has tips that contain cnidosacs (stinging cells absorbed from prey species and then used by the nudibranch).[43] They lack a mantle.[ citation needed] Some are hosts to zooxanthellae.

The accurate systematics of nudibranchs are a topic of recent revision. traditionally, nudibranchs have been treated as the holy order Nudibranchia, located in the gastropod mollusk subclass Opisthobranchia ( the nautical slug : which consisted of sea slug, sidegill slugs, bubble snails, alga sap-sucking ocean slugs, and sea hares ). [ 40 ] Since 2005, [ 44 ] pleurobranchs ( which had previously been grouped among sidegill slugs ) have been placed alongside sea slug in the clade Nudipleura ( recognising them as more closely related to each other than to early opisthobranchs ). [ 45 ] Since 2010, Opisthobranchia has been recognised as not a valid clade ( it is paraphyletic ) and rather Nudipleura has been placed as the first outgrowth of Euthyneura ( which is the prevailing clade of gastropods ). [ 46 ]

traditional hierarchy [edit ]

This classification was based on the work of Johannes Thiele ( 1931 ), [ 47 ] who built on the concepts of Henri Milne-Edwards ( 1848 ). [ 48 ] arrange nudibranchia :

early revisions [edit ]

Newer insights derived from morphologic data and gene-sequence inquiry seemed to confirm those ideas. On the basis of probe of 18S rDNA succession data, strong attest supports the monophyly of the Nudibranchia and its two major groups, the Anthobranchia/Doridoidea and Cladobranchia. [ 49 ] A analyze published in May 2001, again revised the taxonomy of the Nudibranchia. [ 50 ] They were frankincense divided into two major clades :

  • Anthobranchia (= Bathydoridoidea + Doridoidea)
  • Dexiarchia nom. nov. (= Doridoxoidea + Dendronotoidea + Aeolidoidea + “Arminoidea”).

however, according to the taxonomy by Bouchet & Rocroi ( 2005 ), presently the most up-to-date system of classifying the gastropods, the Nudibranchia are a subclade within the clade of the Nudipleura. The Nudibranchia are then divided into two clades :

  • Euctenidiacea (= Holohepatica)
    • Gnathodoridacea (contains only Bathydorididae)
    • Doridacea
      • Doridoidea
      • Phyllidioidea
      • Onchidoridoidea
      • Polyceroidea (= Phanerobranchiata Non Suctoria)
  • Dexiarchia (= Actenidiacea)
    • Pseudoeuctenidiacea ( = Doridoxida)
    • Cladobranchia ( = Cladohepatica)
      • Euarminida
      • Dendronotida
      • Aeolidida
      • Unassigned Cladobranchia (previously Metarminoidea)
        • Charcotiidae
        • Dironidae
        • Goniaeolididae
        • Heroidae
        • Proctonotidae
        • Madrellidae
        • Pinufiidae
        • Embletoniidae

gallery [edit ]

This gallery shows some of the big unevenness in the color and kind of sea slug, and sea slug egg ribbons .

See besides [edit ]

References [edit ]

further read [edit ]

Videos [edit ]