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Heterobranchia
The sea butterfly or pteropod gastropod, Clione limacina
The sea butterfly or pteropod gastropod, Clione limacina
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Orthogastropoda
Superorder: Heterobranchia
Orders

Heterostropha
Opisthobranchia
Pulmonata

Heterobranchia, the heterobranchs, (meaning "different-gilled snails"), is a taxonomic superorder of sea snails, marine gastropod mollusks. 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. An opisthobranch (ō-pĭsʹthə-brăngk is any member of the very large and diverse group of rather specialized highly evolved marine slugs and snails ( marine Gastropod The Pulmonata or "pulmonates" are an order (once a Subclass) of Snails and Slugs that have developed a pallial Lung 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 The word snail is a Common name that can be used for almost all members of the Molluscan class Gastropoda which have coiled shells in the 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

(Note: Gastropod taxonomy has been in flux for many years, and this is especially true currently, because of new research in molecular phylogeny. 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 Because of all this on-going change, different reliable sources can yield very different classifications. This is especially true within groups which are poorly understood in general. )

This superorder contains a diverse and interesting group of families. The similarity in the structure of the gills within this group makes the various families eligible for membership, despite all the other differences they show.

The families included in this recently established superorder of mollusks (G. Haszprunar, 1985) have historically been placed in many different parts of the taxonomic class of gastropods. Earlier authors (as J.E. Gray, 1840) placed the Heterobranchia as a borderline category intermediate between the Opisthobranchia & Pulmonata, and all the other gastropods. John Edward Gray ( 12 February 1800 &ndash 7 March 1875) was a British zoologist. An opisthobranch (ō-pĭsʹthə-brăngk is any member of the very large and diverse group of rather specialized highly evolved marine slugs and snails ( marine Gastropod The Pulmonata or "pulmonates" are an order (once a Subclass) of Snails and Slugs that have developed a pallial Lung

The (sometimes recognized) order Heterostropha within the Heterobranchia, which includes such families as Architectonicidae, the sundial or staircase snails, is primarily characterized by a shell which has a heterostrophic protoconch, in other words the apical whorls are coiled in the opposite plane to the adult whorls. Architectonicidae, or the staircase shells or sundials, are a family of sea Snails marine Gastropod Mollusks A protoconch (meaning first or earliest or original shell is an Embryonic or Larval shell of some classes of Molluscs e The classification of this group has been revised by Ponder & Warén (1988).

(In contrast to the heterobranchs, the bodies of the Opisthobranchia have undergone detorsion (unwinding). They have essentially evolved back to the bilateral symmetry of their ancestors. The mantle cavity of the Pulmonata has modified into an air-breathing organ. They are also characterized by detorsion and a symmetrically-arranged nervous system. The pulmonates usually lack an operculum and are hermaphroditic. 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 A hermaphrodite is an organism having both male and female reproductive organs The order Pulmonata contains most land snails and slugs, many freshwater snails, and a small number of fully marine species. )

Taxonomy of the Heterobranchia

Superorder Heterobranchia J.E. Gray, 1840

New studies, published in 2004, [1] put the monophyletic Pulmonata and the paraphyletic Opisthobranchia together in the clade Euthyneura Spengel 1881. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor . This clade together with the paraphyletic group Heterostropha (pyramidelids and other related groups) define the clade Heterobranchia.

Clade Heterobranchia

Footnotes

  1. ^ Cristina Grande, José Templado, J. Lucas Cervera and Rafael Zardoya (2004). "Molecular Phylogeny of Euthyneura (Mollusca: Gastropoda) (full text on line)". Mol. Biol. Evol. 21 (2).  

References

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