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Opisthobranchia
Notodoris minor
Notodoris minor
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Orthogastropoda
Superorder: Heterobranchia
Order: Opisthobranchia
Milne-Edwards, 1848
Suborders

Cephalaspidea
Sacoglossa
Anaspidea
Notaspidea
Thecosomata
Gymnosomata
Nudibranchia
  Infraorder Anthobranchia
  Infraorder Cladobranchia

An opisthobranch (pronounced /ō-pĭsʹthə-brăngk/) is any member of the very large and diverse group of rather specialized, highly evolved marine slugs and snails (marine gastropod mollusks) known as Opisthobranchia, within the Heterobranchia. Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails Orthogastropoda is one of two major Taxonomic groupings of snails and slugs an extremely large Subclass within the huge class Gastropoda. Heterobranchia, the heterobranchs, (meaning "different-gilled snails" is a Taxonomic Superorder of sea Snails marine Henri Milne-Edwards ( October 23, 1800 - July 29, 1885) was an eminent French Zoologist. The suborder Cephalaspidea, also known as the headshield slugs and bubble shells, is a Suborder of sea slugs and bubble snails marine Sacoglossa, commonly known as the sacoglossans, are a Taxonomic order of small bubble Snails sea Snails and sea Slugs Sea hares ( Aplysia species and related genera are very large sea Slugs with a soft internal shell made of protein Notaspidea, also known as the sidegill slugs, is a Suborder which includes both sea Slugs and sea snails or Limpets marine Sea butterflies, also known as Thecosomata or flapping Snails, are a Taxonomic suborder of Pelagic swimming sea snails Sea angels, also known as cliones, and previously known as one kind of Pteropod, are a group of small swimming sea Slugs. A nudibranch (pronounced (BrE or (AmE is a member of one Suborder of soft-bodied shell-less marine Opisthobranch Gastropod Mollusks Marine is an Umbrella term. As an adjective it is usually applicable to things relating to the Sea or Ocean, such as Marine biology, Marine The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Heterobranchia, the heterobranchs, (meaning "different-gilled snails" is a Taxonomic Superorder of sea Snails marine

This Opisthobranchia include a number of families of bubble snails which have shells, and other headshield slugs in the order Cephalaspidea. The suborder Cephalaspidea, also known as the headshield slugs and bubble shells, is a Suborder of sea slugs and bubble snails marine In addition it includes many other orders, including the saccoglossans, the anaspidean sea hares, the pelagic sea angels and sea butterflies, and a very large number of different families of nudibranchs. Sea hares ( Aplysia species and related genera are very large sea Slugs with a soft internal shell made of protein Sea angels, also known as cliones, and previously known as one kind of Pteropod, are a group of small swimming sea Slugs. Sea butterflies, also known as Thecosomata or flapping Snails, are a Taxonomic suborder of Pelagic swimming sea snails A nudibranch (pronounced (BrE or (AmE is a member of one Suborder of soft-bodied shell-less marine Opisthobranch Gastropod Mollusks

Opisthobranchs are characterized by two pairs of tentacles and a single gill behind and to the right of the heart (from which the group derives its name, Greek opisthen, behind + brankhia, gills). Tentacles can refer to the elongated flexible organs that are present in some animals especially Invertebrates and sometimes to the hairs of the leaves of some insectivorous A gill is an anatomical structure found in many aquatic organisms Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly

The name "opisthobranch" was coined by Johannes Thiele in 1931 as a title for one of what were then considered the three subclasses of Gastropoda (the other two being Prosobranchia and Pulmonata). For the 19th century chemist by the same name see Johannes Thiele (chemist. Year 1931 ( MCMXXXI) was a Common year starting on Thursday (link will display full 1931 calendar of the Gregorian calendar. Prosobranchiagif|thumb|The shell of a Harpa species a prosobranch gastropod]] Prosobranchia used to be a large Taxonomic Subclass of Snails The Pulmonata or "pulmonates" are an order (once a Subclass) of Snails and Slugs that have developed a pallial Lung

This group was once a strict taxonomic order, but recent research in molecular phylogeny revealed Opisthobranchia's polyphyly (separate evolutions), and so the group no longer holds any strict taxonomic sense, being divided into nine different orders (and united with the so-called lower heterobranchs). Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In Phylogenetics, a Taxon is polyphyletic ( Greek for "of many races" if the trait its members have in common evolved separately in different Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used

Contents

Description

Opisthobranchs are principally soft-bodied marine creatures with a reduced or absent shell and no operculum. The operculum, meaning little lid (plural opercula or operculums is a corneous or Calcareous structure which exists in some groups of marine freshwater and land

Their bodies have undergone detorsion, an evolutionary reversal of the 180° torsion of their immediate ancestors. Torsion is a Gastropod Synapomorphy which occurs in all gastropods during Larval development

There is no marked distinction between head and mantle. The tentacles, situated close to the mouth, are used for orientation. Behind them you can find the rhinophores, olfactory organs often with complex forms. A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea Slugs marine Gastropod The middle part of the foot is the sole, used for locomotion. The sides of the foot have evolved into parapodia, fleshy winglike outgrowths. In several suborders, such as the Thecosomata and Gymnosomata, these parapodia are used to move in a swimming motion.

Many have brilliant colors and carry stinging cells, so that predators may learn to avoid them as a food source.

Opisthobranchs and pulmonates

It is speculated that the Opisthobranchia may be paraphyletic (Haszprunar, 1985), having given rise to the Pulmonata, although this is still somewhat disputed. Cladistics is the hierarchical classification of Species based on evolutionary ancestry

The Pulmonata may be a sister group to a particular opisthobranch taxon. Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos The Opisthobranchia are not therefore a monophyletic group and are no longer be accepted as a taxon. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor They are now included in the subclass Orthogastropoda. Orthogastropoda is one of two major Taxonomic groupings of snails and slugs an extremely large Subclass within the huge class Gastropoda. Note that one can still encounter the old classification in many manuals and on most websites. You can find more about these taxonomic issues at the gastropod page. The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails

One version of the taxonomy

Order Opisthobranchia Milne-Edwards, 1848 (sea slugs)

A new phylogentic study, published in November 2004, [1] has given a new definition to the seven main lineages of the Opisthobranchia. Sea butterflies, also known as Thecosomata or flapping Snails, are a Taxonomic suborder of Pelagic swimming sea snails Sea angels, also known as cliones, and previously known as one kind of Pteropod, are a group of small swimming sea Slugs. A nudibranch (pronounced (BrE or (AmE is a member of one Suborder of soft-bodied shell-less marine Opisthobranch Gastropod Mollusks Baron André Étienne Justin Pascal Joseph François d'Audebert de Férussac ( 30 December 1786 - 21 January 1836) was a French

Images

A red-lined bubble shell (Bullina lineata) off the coast of Sydney, Australia. The family Bullinidae are a Taxonomic group of small shelled sea Slugs marine Opistobranch Gastropod Mollusks in the Sydney (ˈsɪdniː is the most populous city in Australia, with a Metropolitan area population of approximately 4 For a topic outline on this subject see List of basic Australia topics.

A sea hare off Morro Bay, California. Sea hares ( Aplysia species and related genera are very large sea Slugs with a soft internal shell made of protein Morro Bay is a waterfront city in San Luis Obispo County, California, United States. California ( is a US state on the West Coast of the United States, along the Pacific Ocean.

A sea hare off Hawaii Island, Hawaii. The Island of Hawaii, also called the Big Island or Hawaii Island, is a volcanic Island in the U The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the

A blue-spotted sea hare (Bursatella leachi) off Lembeh Strait, North Sulawesi, Indonesia. Bitung is a city on the northern coast of the island of Sulawesi in Indonesia. North Sulawesi (Sulawesi Utara is a province of Indonesia. It is on the island of Sulawesi, and borders the province of Gorontalo to the The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia.

A winged snail (Clione limacina), a type of sea angel. Sea angels, also known as cliones, and previously known as one kind of Pteropod, are a group of small swimming sea Slugs.

A Mediterranean sacoglossan, Oxynoe olivacea. Sacoglossa, commonly known as the sacoglossans, are a Taxonomic order of small bubble Snails sea Snails and sea Slugs

A headshield slug (Chelidonura varians) off Tasik Ria, North Sulawesi, Indonesia. North Sulawesi (Sulawesi Utara is a province of Indonesia. It is on the island of Sulawesi, and borders the province of Gorontalo to the The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia.

Another headshield slug (Chelidonura amoena).

A black headshield slug (Chelidonura inornata).

Chelidonura punctata.

A paper bubble shell (Micromelo guamensis) from Fish Rock Cave, South West Rocks, New South Wales. South West Rocks is located on the

A navanax (Navanax inermis) off Santa Catalina Island, California. California ( is a US state on the West Coast of the United States, along the Pacific Ocean.

A maximillate pleurobranch (Pleurobranchis maximillatus) off Fly Point, Port Stephens, New South Wales. Port Stephens is a large natural harbour located about north-east of Sydney in New South Wales, Australia.

A grand pleurobranch (Pleurobranchus grandis) off Dahab, Egypt. Dahab ( دهب) is a small town situated on the southeast coast of the Sinai Peninsula in Egypt. This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics.

An unidentified species of sea butterfly. Sea butterflies, also known as Thecosomata or flapping Snails, are a Taxonomic suborder of Pelagic swimming sea snails

Footnotes

  1. ^ Cristina Grandea, Josè Templadoa, J. Lucas Cerverab and Rafael Zardoya (2004). "Phylogenetic relationships among Opisthobranchia (Mollusca: Gastropoda) based on mitochondrial cox 1, trnV, and rrnL genes". Molecular Phylogenetics and Evolution 33 (2).  

References

External links

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