Nudibranchs () are a group of soft-bodied

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is est ...

s which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to match, such as "clown", "marigold", "splendid", "dancer", "dragon", or "sea rabbit". Currently, about 3,000 valid species of nudibranchs are known.Ocean Portal (2017)
A Collage of Nudibranch Colors
Smithsonian National Museum of Natural History. Retrieved 17 April 2018. The word "nudibranch" comes from the

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

"naked" and the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

() "

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

s". Nudibranchs are often casually called

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary tim ...

s, as they are a family of opistobranchs (sea slugs), within the phylum

Mollusca Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is es ...

(molluscs), but many sea slugs belong to several taxonomic groups which are not closely related to nudibranchs. A number of these other sea slugs, such as the

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

'' Sacoglossa'' and the colourful Aglajidae, are often confused with nudibranchs.

Distribution and habitat

Nudibranchs occur in seas worldwide, ranging from the Arctic, through temperate and tropical regions, to the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...

around Antarctica.Nudibranchs
, Fishermen Scuba. They are almost entirely restricted to salt water, although a few species are known to inhabit lower salinities in

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

. Nudibranchs live at virtually all depths, from the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

to depths well over . The greatest diversity of nudibranchs is seen in warm, shallow reefs, although one nudibranch species was discovered at a depth near . Nudibranchs are

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning " ...

animals, found crawling over the substrate. The only exceptions to this are the neustonic '' Glaucus'' nudibranchs, which float upside down just under the ocean's surface; the

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

nudibranchs '' Cephalopyge trematoides'', which swim in the water column; and '' Phylliroe bucephalum.''

Anatomical description

The body forms of nudibranchs vary a great deal, but because they are opisthobranchs, unlike most other gastropods, they are apparently

bilaterally symmetrical Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pl ...

externally (but not internally) because they have undergone secondary detorsion. In all nudibranchs, the male and female sexual openings are on the right side of the body, reflecting their asymmetrical origins. They lack a

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

cavity. Some species have venomous appendages ( cerata) on their sides, which deter predators. Many also have a simple gut and a mouth with a

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

. The eyes in nudibranchs are simple and able to discern little more than light and dark. The eyes are set into the body, are about a quarter of a millimeter in diameter, and consist of a lens and five photoreceptors. Nudibranchs vary in adult size from . The adult form is without a shell or operculum (in shelled gastropods, the operculum is a bony or horny plate that can cover the opening of the shell when the body is withdrawn). In most species, there is a swimming veliger larva with a coiled shell, but the shell is shed at

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

when the larva transforms into the adult form. Some species have direct development, and the shell is shed before the animal emerges from the egg mass.Thompson, T. E. 1976. Biology of opisthobranch molluscs, vol. 1, 207 pp., 21 pls. Ray Society, no. 151. Blue dragon-glaucus atlanticus (8599051974)

Blue dragon-glaucus atlanticus (8599051974)

The name ''nudibranch'' is appropriate, since the dorids (infraclass

Anthobranchia The Euctenidiacea, common name dorid nudibranchs, are a taxonomic suborder of sea snails or slugs, marine gastropod molluscs in the order Nudibranchia. Bouchet & Rocroi (2005) rejected the name Anthobranchia on the grounds that it also include ...

) breathe through a "naked gill" shaped into branchial plumes in a rosette on their backs. By contrast, on the back of the aeolids in the clade Cladobranchia, brightly coloured sets of protruding organs called cerata are present. Nudibranchs have cephalic (head) tentacles, which are sensitive to touch, taste, and smell. Club-shaped rhinophores detect odors.

Defence mechanisms

In the course of their evolution, nudibranchs have lost their shells, while developing alternative defence mechanisms. Some species evolved an external anatomy with textures and colours that mimicked surrounding sessile invertebrate animals (often their prey sponges or soft corals) to avoid predators (

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

). Other nudibranchs, as seen especially well on Chromodoris quadricolor, have an intensely bright and contrasting colour pattern that makes them especially conspicuous in their surroundings. Nudibranch molluscs are the most commonly cited examples of

aposematism Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste ...

in marine ecosystems, but the evidence for this has been contested, mostly because few examples of

mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry f ...

are seen among species, many species are nocturnal or cryptic, and bright colours at the red end of the spectrum are rapidly attenuated as a function of water depth. For example, the Spanish dancer nudibranch (genus ''

Hexabranchus Hexabranchidae is a monotypic family of colorful nudibranchs (often called "sea slugs") which contains only a single genus ''Hexabranchus'', with two species, and has no subfamilies. This family is one of the many families of dorid nudibranc ...

''), among the largest of tropical marine slugs, potently chemically defended, and brilliantly red and white, is nocturnal and has no known mimics. Other studies of nudibranch molluscs have concluded they are aposematically coloured, for example, the slugs of the family Phylidiidae from Indo-Pacific coral reefs. Nudibranchs that feed on hydrozoids can store the hydrozoids'

nematocyst A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...

s (stinging cells) in the dorsal body wall, the cerata. These stolen nematocysts, called kleptocnidae, wander through the

alimentary tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...

without harming the nudibranch. Once further into the organ, the cells are assimilated by intestinal protuberances and brought to specific placements on the creature's hind body. Nudibranchs can protect themselves from the hydrozoids and their nematocysts; the specific mechanism is yet unknown, but special cells with large

vacuole A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic m ...

s probably play an important role. Similarly, some nudibranchs can also take in plant cells (symbiotic algae from soft corals) and reuse these to make food for themselves. The related group of sacoglossan sea slugs feed on algae and retain just the chloroplasts for their own photosynthetic use, a process known as kleptoplasty. Nudibranchs use a variety of chemical defences to aid in protection,, a comprehensive review of the chemical ecology of the nudibranchs but it is not necessary for the strategy to be lethal to be effective; in fact, good arguments exist that chemical defences should evolve to be distasteful rather than toxic. Some sponge-eating nudibranchs concentrate the chemical defences from their prey sponge in their bodies, rendering themselves distasteful to predators. One method of chemical defense used by nudibranchs are secondary metabolites, which play an important role in mediating relationships among marine communities. The evidence 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 nudibranchs, respectively. Furthermore, nudibranchs contain a mixture of sponge chemicals when they are in the presence of multiple food sources, as well as change defence chemicals with a concurrent change in diet. This, however, is not the only way for nudibranchs to develop chemical defences. Certain Antarctic marine species defense mechanisms are believed to be controlled by biological factors like predation and competition, and selective pressures. Certain species are able to produce their own chemicals ''de novo'' without dietary influence. Evidence for the different methods of chemical production comes with the characteristic uniformity of chemical composition across drastically different environments and geographic locations found throughout ''de novo'' production species compared to the wide variety of dietary and environmentally dependent chemical composition in sequestering species. Another method of protection is the release of the ugdon acid from the skin. Once the specimen is physically irritated or touched by another creature, it will release the mucus automatically, eating the animal from the inside out.

Apparent production of sound

In 1884, Philip Henry Gosse reported observations by "Professor Grant" (possibly Robert Edmond Grant) that two species of nudibranchs emit sounds that are audible to humans.

Two very elegant species of Sea-slug, viz., ''Eolis punctata'' .e._''Facelina_annulicornis''.html" ;"title="Facelina_annulicornis.html" ;"title=".e. ''Facelina annulicornis">.e. ''Facelina annulicornis''">Facelina_annulicornis.html" ;"title=".e. ''Facelina annulicornis">.e. ''Facelina annulicornis'' and ''Tritonia arborescens'' [i.e. ''Dendronotus frondosus''], certainly produce audible sounds. Professor Grant, who first observed the interesting fact in some specimens of the latter which he was keeping in an aquarium, says of the sounds, that 'they resemble very much the clink of a steel wire on the side of the jar, one stroke only been given at a time, and repeated at intervals of a minute or two; when placed in a large basin of water the sound is much obscured, and is like that of a watch, one stroke being repeated, as before, 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 motion; in the dark I have not observed any light emitted at the time of the stroke; no globule of air escapes to the surface of the water, nor is any ripple produced on the surface at the instant 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 very little diminution of their original intensity. In a small apartment they are audible at the distance of twelve feet. The sounds obviously proceed from the mouth of the animal; and at the instant of the stroke, we observe the lips suddenly separate, as if to allow the water to rush into a small vacuum formed within. As these animals are hermaphrodites, requiring mutual impregnation, the sounds may possibly be a means of communication between them, or, if they are of an electric nature, they may be the means of defending from foreign enemies one of the most delicate, defenceless, and beautiful Gasteropods that inhabit the deep.

Lifecycle

Editing Image-Acanthodoris lutea laying eggs 2

Nudibranchs are

hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have s ...

, thus having a set of reproductive organs for both sexes, but they cannot fertilize themselves. Mating usually takes a few minutes, and involves a dance-like courtship. Nudibranchs typically deposit their eggs within a gelatinous spiral, which is often described as looking like a ribbon. The number of eggs varies; it can be as few as just 1 or 2 eggs ('' Vayssierea felis'') or as many as an estimated 25 million ('' Aplysia fasciata''). The eggs contain

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849 ...

s from sea sponges as a means of deterring predators. After hatching, the infants look almost identical to their adult counterparts, albeit smaller. Infants may also have fewer cerata. The lifespan of nudibranchs can range from a few weeks to a year, depending on the species.

Feeding and ecological role

All known nudibranchs are

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

. Some feed on

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throu ...

s, others on hydroids (e.g. '' Cuthona''), others on

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...

ns ( phanerobranchs such as '' Tambja'', ''Limacia, Plocamopherus'' and ''Triopha''), and some eat other sea slugs or their eggs (e.g. ''

Favorinus Favorinus (c. 80 – c. 160 AD) was a Roman sophist and academic skeptic philosopher who flourished during the reign of Hadrian and the Second Sophistic. Early life He was of Gaulish ancestry, born in Arelate (Arles). He received a ref ...

'') or, on some occasions, are

cannibal Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, bo ...

s and prey on members of their own species. Other groups feed on

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one t ...

s (e.g. ''

Nembrotha ''Nembrotha'' is a genus of sea slugs, nudibranchs, marine (ocean), marine gastropod molluscs in the family Polyceridae. ''Nembrotha'' is the type genus of the subfamily Nembrothinae. Species Species in the genus Nembrotha include: * ''Nembr ...

'', '' Goniodoris''), other nudibranchs ('' Roboastra'', which are descended from tunicate-feeding species),

barnacle A barnacle is a type of arthropod constituting the subclass 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 erosiv ...

s (e.g. ''Onchidoris bilamellata''), and

anemone ''Anemone'' () is a genus of flowering plants in the buttercup family Ranunculaceae. Plants of the genus are commonly called windflowers. They are native to the temperate and subtropical regions of all continents except Australia, New Zealand an ...

s (e.g. the

Aeolidiidae Aeolidiidae, a family of aeolid nudibranchs, are a family of sea slugs, shell-less marine gastropod molluscs.Bouchet, P. (2014)''Aeolidiidae'' Gray, 1827.Accessed through: World Register of Marine Species on 2014-10-24 Most, or perhaps all, mem ...

and other Cladobranchia). The surface-dwelling nudibranch, ''

Glaucus atlanticus ''Glaucus atlanticus'' (common names include the blue sea dragon, sea swallow, blue angel, blue glaucus, dragon slug, blue dragon, blue sea slug and blue ocean slug) is a species of small, blue sea slug, a pelagic (open-ocean) aeolid nudibra ...

'', is a specialist predator of siphonophores, such as the

Portuguese man o' war The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or blue bottle, which is ...

. This predatory mollusc sucks air into its stomach to keep it afloat, and using its muscular foot, it clings to the surface film. If it finds a small victim, ''Glaucus'' simply envelops it with its capacious mouth, but if the prey is a larger siphonophore, the mollusc nibbles off its fishing tentacles, the ones carrying the most potent nematocysts. Like some others of its kind, ''Glaucus'' does not digest the

nematocysts A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...

; instead, it uses them to defend itself by passing them from its gut to the surface of its skin.

Taxonomy

Nudibranchs are commonly divided into two main kinds, dorid and aeolid (also spelled eolid) nudibranchs:Hans Bertsch
Nudibranchs: Marine slugs with verve
"Navanax inermis .is the bane of all nudibranchs, because it is one of the few known predators on this group of slugs. ..Dorids mainly eat sponges, bryozoans, and tunicates, whereas aeolids principally eat cnidarians." *Dorids (clade

, 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. 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. *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). They lack a mantle. Some are hosts to

zooxanthella Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus '' Sym ...

e. The exact systematics of nudibranchs are a topic of recent revision. Traditionally, nudibranchs have been treated as the order Nudibranchia, located in the gastropod mollusc subclass

Opisthobranchia Opisthobranchs () is now an informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping. Euopi ...

(the marine slugs: which consisted of nudibranchs, sidegill slugs,

bubble snails ''Bulla'' is a genus of medium to large hermaphrodite sea snails, shelled marine opisthobranch gastropod molluscs. These herbivorous snails are in the suborder Cephalaspidea, headshield slugs, and the order Opisthobranchia.Gofas, S. (2010). ...

, algae sap-sucking sea slugs, and

sea hares The clade Anaspidea, commonly known as sea hares (''Aplysia'' species and related genera), are medium-sized to very large opisthobranch gastropod molluscs with a soft internal shell made of protein. These are marine gastropod molluscs in the ...

). Since 2005, pleurobranchs (which had previously been grouped among sidegill slugs) have been placed alongside nudibranchs in the clade Nudipleura (recognising them as more closely related to each other than to other opisthobranchs). Since 2010, Opisthobranchia has been recognised as not a valid clade (it is

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

) and instead Nudipleura has been placed as the first offshoot of

Euthyneura Euthyneura is a taxonomic infraclass of snails and slugs, which includes species exclusively from marine, aquatic and terrestrial gastropod mollusks in the clade Heterobranchia. Euthyneura are characterised by several autapomorphies, but ar ...

(which is the dominant clade of gastropods).

Traditional hierarchy

This classification was based on the work of

Johannes Thiele Johannes Thiele may refer to: *Johannes Thiele (zoologist) *Johannes Thiele (chemist) Friedrich Karl Johannes Thiele (May 13, 1865 – April 17, 1918) was a German chemist and a prominent professor at several universities, including those in ...

(1931), who built on the concepts of

Henri Milne-Edwards Henri Milne-Edwards (23 October 1800 – 29 July 1885) was an eminent French zoologist. Biography Henri Milne-Edwards was the 27th child of William Edwards, an English planter and colonel of the militia in Jamaica and Elisabeth Vaux, a French ...

(1848).

Nudibranch (Charleston, South Carolina, 5 March 1852)

Order Nudibranchia: * Infraorder

Férussac, 1819 (dorids) ** Superfamily Doridoidea Rafinesque, 1815 ** Superfamily Doridoxoidea Bergh, 1900 ** Superfamily Onchidoridoidea Alder & Hancock, 1845 ** Superfamily Polyceroidea Alder & Hancock, 1845 * Infraorder Cladobranchia Willan & Morton, 1984 (aeolids) ** Superfamily

Aeolidioidea Aeolidioidea is a superfamily of sea slugs, the aeolid nudibranchs. They are marine gastropod molluscs in the suborder Cladobranchia. Taxonomy As of 2019, the superfamily Aeolidioidea consisted of the following families: * Aeolidiidae Gray, 1 ...

J. E. Gray, 1827 ** Superfamily Arminoidea Rafinesque, 1814 ** Superfamily

Dendronotoidea Dendronotoidea is a taxonomic superfamily of small colorful sea slugs or nudibranchs, aeolid nudibranchs. MolluscaBase eds. (2022). MolluscaBase. Dendronotoidea Allman, 1845. Accessed through: World Register of Marine Species at: http://www.ma ...

Allman, 1845 ** Superfamily Metarminoidea Odhner in Franc, 1968

Early revisions

Newer insights derived from morphological data and gene-sequence research seemed to confirm those ideas. On the basis of investigation of 18S rDNA sequence data, strong evidence supports the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

of the Nudibranchia and its two major groups, the Anthobranchia/Doridoidea and Cladobranchia. A study published in May 2001, again revised the taxonomy of the Nudibranchia. They were thus divided into two major clades: *

Bathydoridoidea ''Bathydorididae'' is a taxonomic family of dorid nudibranch, shell-less marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine bio ...

+ Doridoidea) * Dexiarchia nom. nov. (= Doridoxoidea + Dendronotoidea + Aeolidoidea + "Arminoidea"). However, according to the taxonomy by Bouchet & Rocroi (2005), currently the most up-to-date system of classifying the gastropods, the Nudibranchia are a subclade within the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

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 Dendronotoidea is a Taxonomy (biology), taxonomic superfamily (zoology), superfamily of small colorful sea slugs or nudibranchs, aeolid nudibranchs. MolluscaBase eds. (2022). MolluscaBase. Dendronotoidea Allman, 1845. Accessed through: World Re ...

***

Aeolidida The Aeolidida is a taxonomic clade of sea slugs, specifically aeolid nudibranchs, marine gastropod molluscs in the clade Cladobranchia. They are distinguished from other nudibranchs by their possession of cerata containing cnidosacs. Ta ...

***Unassigned Cladobranchia (previously Metarminoidea) **** Charcotiidae **** Dironidae **** Goniaeolididae **** Heroidae **** Proctonotidae **** Madrellidae **** Pinufiidae **** Embletoniidae

Gallery

This gallery shows some of the great variability in the color and form of nudibranchs, and nudibranch egg ribbons. File:Tritoniopsis elegans.jpg, '' Tritoniopsis elegans'' File:Nembrotha cristata bunaken.jpg, '' Nembrotha cristata'', in Bunaken National Park File:Nudibranch in tidepool.jpg, Clown nudibranch ''

Triopha catalinae ''Triopha catalinae'', commonly known as the sea clown triopha or sea clown, is a species of colorful sea slug called a nudibranch. Sea clowns are a shell-less marine, gastronomic mollusk in the taxonomic family Polyceridae. The species' Lat ...

'', Northern

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

File:Chromodoris annae.JPG, ''

Chromodoris annae ''Chromodoris annae'' is a species of sea slug, a very colourful nudibranch, a shell-less marine gastropod mollusc in the family Chromodorididae. Distribution This species of nudibranch is found in the central area of the Indo-Pacific region ...

'' from Lembeh Straits,

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...

File:Bailarina Española por Gustavo Gerdel.jpg, Spanish dancer taken at night, Red Sea File:Nembrotha chamberlaini (AA1).jpg, '' Nembrotha chamberlaini'' from Verde Island, the Philippines File:Glossodoris atromarginata.jpg, '' Glossodoris atromarginata'' File:Chromodoris dianae (AA2).jpg, ''

Chromodoris dianae ''Chromodoris dianae'' is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusc in the family Chromodorididae. Distribution This species is known only from the Philippines, Indonesia and Borneo.Rudman, W.B., 1998 (A ...

'' from Verde Island, the Philippines File:Nembrotha milleri mating.jpg, A pair of '' Nembrotha milleri'' mating at Verde Island, the Philippines File:Regal Sea Goddess Nudibranch.jpg, Regal sea goddess '' Felimare picta'' in the Gray's Reef National Marine Sanctuary, Savannah, Georgia File:Flabellina Affinis - La Herradura.jpg, '' Flabellina affinis'' at La Herradura (Mediterranean Sea) Spain File:Eggs of nudibranch.JPG, Dorid nudibranch egg ribbon in Moss Beach, California File:Nudibranch egg ribbon at Shaab Mahmoud.JPG, Nudibranch egg ribbon at Shaab Mahmoud (

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...

) File:Nudibranch egg ribbon at Malahi.JPG, Nudibranch egg ribbon at Malahi (

) File:Goniobranchus Kuniei.jpg, Goniobranchus kuniei, off the coast of

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

File:Nudi branch.jpg, Nudibranch

References

External links

Sea Slug Forum
by William B. Rudman
Nudibranchs of the British Isles

OPK Opistobranquis – Iberian and Mediterranean Opisthobranchs

* ttp://slugsite.tierranet.com The Slug Site, Michael D. Miller 2002–2014
The Okinawa Slug Site

Images, information and identification of Nudibranchs

Nudibranch Photos by Mick Tait

Nudibranchs in their natural environment, Scuba Diving – Narooma NSW offline? 26 Nov 2014

Nudi Pixel: Online resource for nudibranchs and sea slugs identification using photographs

* ttps://web.archive.org/web/20100107002612/http://www.sergeyphoto.com/underwater/nudibranchs.html Nudibranch gallery- Sergey Parinov – offline? 26 Nov 2014
Opisthobranch Newsletter – Bibliography and portal to opisthobranch, nudibranch & seaslug information

Scottish Nudibranchs: Online resource for identification of species found in Scottish waters

National Geographic Nudibranch Photo Gallery

Sea Slugs of Hawaii

Slug City – ''Molluscs. Brain & Behavior''
from the

University of Illinois at Urbana-Champaign The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Un ...

Videos

Attack of the Sea Slugs
at YouTube
The Lynx Nudibranch
HD clip of ''Phidiana lynceus'' carefully consuming a hydroid ''Myrionema amboinense''.

many videos of nudibranchs from the

{{Authority control Nudipleura Taxa named by Georges Cuvier