Vetigastropoda is a major
taxonomic
Taxonomy is the practice and science of categorization or classification.
A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
group of
sea snail
Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...
s,
marine 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 ...
mollusk
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 e ...
s that form a very ancient
lineage
Lineage may refer to:
Science
* Lineage (anthropology), a group that can demonstrate its common descent from an apical ancestor or a direct line of descent from an ancestor
* Lineage (evolution), a temporal sequence of individuals, populati ...
. Taxonomically the Vetigastropoda are sometimes treated as an
order, although they are treated as an unranked
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 term, ...
in
Bouchet and Rocroi, 2005.
Vetigastropods are considered to be among the most primitive living gastropods,
and are widely distributed in all
ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
s of the world. Their habitats range from the
deep sea
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...
to
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 o ...
s. Many have
shell
Shell may refer to:
Architecture and design
* Shell (structure), a thin structure
** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses
** Thin-shell structure
Science Biology
* Seashell, a hard o ...
s with slits or other secondary openings. One of their main characteristics is the presence of intersected crossed platy shell structure.
Most vetigastropods have some bilateral asymmetry of their
organ systems.
Description
Vetigastropods range in size from approximately 0.08 in (2 mm) long in the case of
Scissurelloidea or
Skeneoidea, to more than 11.8 in (300 mm) in length, as with the
Haliotoidea
Haliotoidea is a superfamily of sea snails, marine gastropod mollusks in the subclass Vetigastropoda (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Vald ...
. External colours and patterns are typically drab, but such groups as the
Tricolioidea and some
Trochoidea and
Pleurotomarioidea
Pleurotomarioidea is a superfamily of small to large marine gastropods included in the order Pleurotomariida of the subclass Vetigastropoda.
These are the slit shells, originally named Pleurotomariacea, in keeping with the convention for namin ...
have bright colours and glossy shells. The clade is characterized by having an intersected crossed platy shell structure.
Shells range from elongate turret-shaped structures, to near-spherical. Shell sculpture varies greatly from simple concentric growth lines, which may or may not be barely visible on the shell surface, to heavy radial and axial ribbing. The shell aperture is normally oval, and often tangential to the coiling axis. Most species have an
operculum (a small lid-like organ). Within the shell, Vetigastropods have a single pair of cephalic tentacles, and a distinct snout containing the mouth. The lateral sides of the body typically have sensory epipodial tentacles.
Distribution
Vetigastropods are found throughout all oceans of the world, including
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
areas, temperate regions, and under
polar ice
A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice.
There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor a ...
.
Habitat
Vetigastropods are present in most marine environments from intertidal zones to the deep sea. They exist on rocky substrates, in soft sediments, and some have been found at deep-sea
hydrothermal vent
A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspot ...
s and cold seeps.
Behaviour
Most vetigastropods are
dioecious
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...
, although some deep-sea varieties are
hermaphrodites
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 sep ...
. Vetigastropods usually eject their gametes directly into the sea for fertilization, thus there is no courtship or mating between individuals for most species.
Diet
Vetigastropods typically feed on such organisms as
bryozoans,
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 time ca ...
s, and
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 through t ...
s. Several species such as
Haliotoidea
Haliotoidea is a superfamily of sea snails, marine gastropod mollusks in the subclass Vetigastropoda (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Vald ...
and
Trochoidea have evolved to feed directly on such plant material as
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
and marine
angiosperm
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s. Deep-sea vetigastropods typically consume sediment.
Reproduction
Vetigastropods normally have very small eggs that produce
lecithotrophic
Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and m ...
(yolk feeding) or non-feeding
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
e. Many vetigastropods secrete
egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
envelopes and have glandular pallial structures that produce masses of jelly-coated eggs.
Larger species typically have yearly cycles of spawning, and produce millions of eggs per reproductive season. Smaller species produce fewer eggs, but can spawn year round.
Taxonomy
The Vetigastropoda have been referred to as a superorder as recently as at least 2007, by M. Harzhauser and in 2005 by D. Heidelberger and L. Koch following
Ponder & Lindberg, 1997, although
Bouchet & Rocroi, 2005 refer to this group simply as a clade, leaving taxonomic determination as a future option. The World Register of Marine Species (WoRMS) follows Bouchet & Rocroi regarding the taxonomic content of the Gastropoda but gives ranks to the higher taxa and defines Vetigastropoda as a subclass.
Bouchet & Rocroi, 2005 treats the Vetigastropoda as a major clade and as a sister clade to the
Caenogastropoda
Caenogastropoda is a taxonomic clade, a large diverse group which are mostly sea snails and other marine gastropod mollusks, but also includes some freshwater snails and some land snails. The clade is the most diverse and ecologically successfu ...
but includes the Vetigastropoda in what are referred to as Basal taxa that are certainly Gastropoda. Ponder & Lindberg, 1997 previously assigned the Vetigastropoda, as a superorder, to the Subclass
Orthogastropoda
Orthogastropoda was a major taxonomic grouping of snails and slugs, an extremely large subclass within the huge class Gastropoda according to the older taxonomy of the Gastropoda (Ponder & Lindberg, 1997).
This taxon is no longer used accordin ...
.
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analysis indicates that this
taxon
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
is one of the four natural groups within the Gastropoda: Vetigastropoda,
Caenogastropoda
Caenogastropoda is a taxonomic clade, a large diverse group which are mostly sea snails and other marine gastropod mollusks, but also includes some freshwater snails and some land snails. The clade is the most diverse and ecologically successfu ...
,
Patellogastropoda
The Patellogastropoda, common name true limpet
Limpets are a group of aquatic snails that exhibit a conical shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning th ...
, and
Heterobranchia
Heterobranchia, the ''heterobranchs'' (meaning "different-gilled snails"), is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.
Heterobranchia is one of the main clades of gastropods. Curr ...
. Research on the
mitochondria
A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
l
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
arrangement has shown that the Vetigastropoda (and Caenogastropoda) mostly retain the ancestral
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
arrangement.
Superfamilies
Superfamilies within the Vetigastropoda include:
* Not assigned to a superfamily within Vetigastropoda are:
** the families:
Ataphridae Cossmann, 1915,
Pendromidae Warén, 1991 (synonym: Trachysmatidae
Thiele, 1925), †
Schizogoniidae
** the genera: ''
Sahlingia''
Warén & Bouchet, 2001
*Superfamily †
Amberleyoidea
*Superfamily
Angarioidea (created as a new superfamily by Williams et al. (2008).
)
*Superfamily †
Eotomarioidea
*Superfamily
Fissurelloidea Flemming, 1822 - keyhole limpets
*Superfamily
Haliotoidea
Haliotoidea is a superfamily of sea snails, marine gastropod mollusks in the subclass Vetigastropoda (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Vald ...
Rafinesque
Constantine Samuel Rafinesque-Schmaltz (; October 22, 1783September 18, 1840) was a French 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ultimat ...
, 1815 - abalones
*Superfamily
Lepetelloidea
*Superfamily
Lepetodriloidea
Lepetodriloidea is a superfamily of small to large sea snails, hydrothermal vent limpets, marine gastropod mollusks in the clade Vetigastropoda
Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form ...
McLean, 1988 - hydrothermal vent limpets
*Superfamily †
Murchisonioidea
Murchisonioidea is an extinct superfamily of small to large sea snails, marine gastropod mollusks in the clade Vetigastropoda.
This superfamily was previously included in the Caenogastropoda by Ponder and Warén (1988) and by Bandel in studies ...
*Superfamily
Neomphaloidea
Neomphaloidea is a Taxonomic rank, superfamily of deep-sea snails or limpets, marine (ocean), marine gastropod mollusc, mollusks. Neomphaloidea is the only superfamily in the order Neomphalida.
The order Neomphalida has the largest ''In situ#Bi ...
: belongs in its own independent clade, the Neomphalina, outside the Vetigastropoda
*Superfamily
Phasianelloidea
Trochoidea is a superfamily of small to very large vetigastropod sea snails with gills and an operculum.Gofas, S. (2013). Trochoidea. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id= ...
*Superfamily
Pleurotomarioidea
Pleurotomarioidea is a superfamily of small to large marine gastropods included in the order Pleurotomariida of the subclass Vetigastropoda.
These are the slit shells, originally named Pleurotomariacea, in keeping with the convention for namin ...
Swainson, 1840 - slit snails: a sister clade to Neomphalina
*Superfamily †
Porcellioidea
Porcellioidea is an extinct superfamily of small to large sea snails, marine gastropod mollusks in the clade Vetigastropoda.
This superfamily dates back to the Paleozoic. They developed sinistrally (left-handed) or planispirally coiled teleocon ...
*Superfamily
Scissurelloidea
*Superfamily
Seguenzioidea
Seguenzioidea is a superfamily of minute to medium-sized sea snails, marine gastropod mollusks in the clade Vetigastropoda.Gofas, S. (2010). Seguenzioidea. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Acce ...
Verrill, 1884
*Superfamily
Trochoidea Rafinesque
Constantine Samuel Rafinesque-Schmaltz (; October 22, 1783September 18, 1840) was a French 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ultimat ...
, 1815 - top snails
*Superfamily
Turbinoidea
Turbinoidea was a superfamily of small to large sea snails, marine gastropod mollusks in the clade Vetigastropoda (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). But it has become an available name, because it is no lon ...
- turban snails - In 2008 this superfamily has been split into Trochoidea and Phasianelloidea
References
External links
*
Herbert D.G. (2015). An annotated catalogue and bibliography of the taxonomy, synonymy and distribution of the Recent Vetigastropoda of South Africa (Mollusca). Zootaxa. 4049(1): 1-98Gastropod taxonomy at PalaeosGastropod reproductive behaviorGastropod NeuroscienceReconstructions of fossil gastropods
{{Taxonbar, from=Q141527
Gastropod taxonomy