Neogastropoda
Encyclopedia
Neogastropoda is an unranked taxonomic clade
of sea snails, marine
gastropod mollusks. For many years prior to 2005 Neogastropoda was an order
.
origin of the group followed by two rapid diversification rounds in the late Cretaceous
and the Paleocene
.
These sea snails only have one auricle, one kidney
and one monopectinate gill
, i.e. the gill filaments develop on only one side of the central axis.
The shell
has a well-developed siphonal canal
. The elongated trunk-like siphon
is an extensible tube, formed from a fold in the mantle
. It is used to suck water into the mantle cavity. At the base of the siphon is the bipectinate (branching from a central axis) osphradium
, a sensory receptacle and olfactory
organ, that is more developed than the one in the Mesogastropoda. They achieved important morphological changes including e.g., the elongation of the siphonal canal
, a shift in the mouth opening to a terminal position on the head, and the formation of a well-developed proboscis
.
The nervous system is very concentrated. Many species have the ganglia
in a compact space.
The rachiglossate (rasp-like) radula
, a layer of serially arranged teeth within the mouth, has only three denticles (small teeth) in each transverse row.
The Neogastropoda have separate sexes
.
There are about 16,000 species. Neogastropoda includes many well-known gastropods including the cone snail
s, conch
s, mud snails, olive snails, oyster drills, tulip shell
s, and whelk
s. The Neogastropoda all live in the sea, except Clea, a freshwater genus. The neogastropods are most diverse in tropical seas. They are mostly predators, but some are saprophagous (scavengers).
the clade Neogastropoda consists of these superfamilies:
When Neogastropoda was an order, it was placed within the prosobranch gastropods according to the taxonomy developed by Thiele
(1921). The families which used to form the order Neogastropoda are now included in the clade Neogastropoda Cox, 1960.
Ever since Thiele (1929), Neogastropoda have been considered a natural group, clearly differentiated from other Caenogastropoda. The monophyly of the group is widely accepted among morphologists, and it is based on several synapomorphies
mostly related with the anatomy of the digestive system
. Current classifications of Neogastropoda generally recognize up to six superfamilies: Buccinoidea, Muricoidea, Olivoidea, Pseudolivoidea, Conoidea, and Cancellarioidea. Phylogenetic relationships among neogastropod superfamilies based on morphological characters are rather unstable, and for instance, Cancellarioidea or Buccinoidea
have been alternatively proposed as the sister group of the remaining Neogastropoda.
the taxonomy of clade Neogastropoda is as follows:
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of sea snails, marine
Marine (ocean)
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 ecology and marine geology...
gastropod mollusks. For many years prior to 2005 Neogastropoda was an order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
.
Description
The available fossil record of Neogastropoda is relatively complete, and supports a widely accepted evolutionary scenario of an Early CretaceousEarly Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
origin of the group followed by two rapid diversification rounds in the late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
and the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
.
These sea snails only have one auricle, one kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
and one monopectinate gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
, i.e. the gill filaments develop on only one side of the central axis.
The shell
Mollusc shell
The mollusc shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes...
has a well-developed siphonal canal
Siphonal canal
Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is drawn into the mantle cavity and over the gill and which serves as a chemoreceptor to locate food. In many carnivorous snails, where the siphon is particularly long, the structure...
. The elongated trunk-like siphon
Siphon
The word siphon is sometimes used to refer to a wide variety of devices that involve the flow of liquids through tubes. But in the English language today, the word siphon usually refers to a tube in an inverted U shape which causes a liquid to flow uphill, above the surface of the reservoir,...
is an extensible tube, formed from a fold in the mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
. It is used to suck water into the mantle cavity. At the base of the siphon is the bipectinate (branching from a central axis) osphradium
Osphradium
The osphradium is the olfactory organ in certain molluscs, linked with the respiration organ.The main function of this is to test incoming water for silt and other possible food particles.It is used by all members of the Genus Conus....
, a sensory receptacle and olfactory
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
organ, that is more developed than the one in the Mesogastropoda. They achieved important morphological changes including e.g., the elongation of the siphonal canal
Siphonal canal
Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is drawn into the mantle cavity and over the gill and which serves as a chemoreceptor to locate food. In many carnivorous snails, where the siphon is particularly long, the structure...
, a shift in the mouth opening to a terminal position on the head, and the formation of a well-developed proboscis
Proboscis
A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In simpler terms, a proboscis is the straw-like mouth found in several varieties of species.-Etymology:...
.
The nervous system is very concentrated. Many species have the ganglia
Ganglion
In anatomy, a ganglion is a biological tissue mass, most commonly a mass of nerve cell bodies. Cells found in a ganglion are called ganglion cells, though this term is also sometimes used to refer specifically to retinal ganglion cells....
in a compact space.
The rachiglossate (rasp-like) radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
, a layer of serially arranged teeth within the mouth, has only three denticles (small teeth) in each transverse row.
The Neogastropoda have separate sexes
Dioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...
.
There are about 16,000 species. Neogastropoda includes many well-known gastropods including the cone snail
Cone snail
Conidae is a taxonomic family of minute to quite large sea snails, marine gastropod molluscs in the superfamily Conoidea.The snails within this family are sophisticated predatory animals...
s, conch
Conch
A conch is a common name which is applied to a number of different species of medium-sized to large sea snails or their shells, generally those which are large and have a high spire and a siphonal canal....
s, mud snails, olive snails, oyster drills, tulip shell
Tulip shell
Tulip snail, or Tulip shell is the common name for two or three species of large, predatory, subtropical and tropical sea snails from the Western Atlantic. These species are in the genus Fasciolaria...
s, and whelk
Whelk
Whelk, also spelled welk or even "wilks", is a common name used to mean one or more kinds of sea snail. The species, genera and families referred to using this common name vary a great deal from one geographic area to another...
s. The Neogastropoda all live in the sea, except Clea, a freshwater genus. The neogastropods are most diverse in tropical seas. They are mostly predators, but some are saprophagous (scavengers).
Taxonomy
According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005)Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
the clade Neogastropoda consists of these superfamilies:
- BuccinoideaBuccinoideaBuccinoidea is a taxonomic superfamily of very small to large predatory sea snails, marine gastropod mollusks.This superfamily is in the clade Neogastropoda according to the taxonomy of the Gastropoda...
Rafinesque, 1815 - MuricoideaMuricoideaMuricoidea is a taxonomic superfamily of predatory sea snails, marine gastropod mollusks in the clade Neogastropoda.This superfamily includes the murex snails, the chank snails, the true whelks, the dove snails, the crown conchs and busycon whelks, the spindle and tulip snails, the volutes and...
Rafinesque, 1815 - OlivoideaOlivoideaOlivoidea is a taxonomic superfamily of minute to medium-large predatory sea snails, marine gastropod mollusks in the clade Neogastropoda.-Taxonomy:...
Latreille, 1825 - PseudolivoideaPseudolivoideaPseudolivoidea is a taxonomic superfamily of sea snails, marine gastropod mollusks in the clade Neogastropoda.-Taxonomy:According to the taxonomy of the Gastropoda by Bouchet & Rocroi the superfamily Pseudolivoidea has two families:...
(de Gregorio, 1880) - ConoideaConoideaConoidea is a superfamily of predatory sea snails, marine gastropod mollusks within the suborder Hypsogastropoda. This superfamily is a very large group of marine mollusks, estimated at about 340 recent valid genera and subgenera, and considered by one authority to contain 4,000 named living species...
Fleming, 1822 - Cancellarioidea Forbes & Hanley, 1851
When Neogastropoda was an order, it was placed within the prosobranch gastropods according to the taxonomy developed by Thiele
Johannes Thiele
Johannes Thiele, full name Karl Hermann Johannes Thiele was a German zoologist specialized in malacology. His Handbuch der systematischen Weichtierkunde is a standard work...
(1921). The families which used to form the order Neogastropoda are now included in the clade Neogastropoda Cox, 1960.
Ever since Thiele (1929), Neogastropoda have been considered a natural group, clearly differentiated from other Caenogastropoda. The monophyly of the group is widely accepted among morphologists, and it is based on several synapomorphies
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
mostly related with the anatomy of the digestive system
Digestive system of gastropods
The digestive system of gastropods has evolved to suit almost every kind of diet and feeding behavior. Gastropods as the largest taxonomic class of the mollusca are very diverse indeed: the group includes carnivores, herbivores, scavengers, filter feeders, and even parasites.In particular, the...
. Current classifications of Neogastropoda generally recognize up to six superfamilies: Buccinoidea, Muricoidea, Olivoidea, Pseudolivoidea, Conoidea, and Cancellarioidea. Phylogenetic relationships among neogastropod superfamilies based on morphological characters are rather unstable, and for instance, Cancellarioidea or Buccinoidea
Buccinoidea
Buccinoidea is a taxonomic superfamily of very small to large predatory sea snails, marine gastropod mollusks.This superfamily is in the clade Neogastropoda according to the taxonomy of the Gastropoda...
have been alternatively proposed as the sister group of the remaining Neogastropoda.
Families
According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005)Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
the taxonomy of clade Neogastropoda is as follows:
- Unassigned to a superfamily
- † Family JohnwyattiidaeJohnwyattiidaeJohnwyattiidae is an extinct taxonomic family of fossil sea snails, marine gastropod mollusks....
- † Family PerissityidaePerissityidaePerissityidae is an extinct taxonomic family of sea snails, i.e., marine gastropod mollusks....
- † Family SarganidaeSarganidaeSarganidae is an extinct taxonomic family of sea snails, marine gastropod mollusks....
- † Family SpeightiidaeSpeightiidaeSpeightiidae is an extinct taxonomic family of sea snails, marine gastropod mollusks.This family is not assigned to a superfamily. It has been traditionally classified near the family Turridae. But in 1993 it has been shown that many if not all species from this family should fall under the family...
- † Family TaiomidaeTaiomidaeTaiomidae is an extinct taxonomic family of sea snails, marine gastropod mollusks....
- † Family WeeksiidaeWeeksiidaeWeeksiidae is an extinct taxonomic family of sea snails, marine gastropod mollusks....
- † Family Johnwyattiidae
- Superfamily BuccinoideaBuccinoideaBuccinoidea is a taxonomic superfamily of very small to large predatory sea snails, marine gastropod mollusks.This superfamily is in the clade Neogastropoda according to the taxonomy of the Gastropoda...
- Family BuccinidaeBuccinidaeBuccinidae is a very large and diverse taxonomic family of large sea snails, often known as whelks or true whelks.True whelks are mostly marine gastropod mollusks in the clade Neogastropoda...
- Family ColubrariidaeColubrariidaeColubrariidae is a taxonomic family of medium-sized sea snails, marine gastropod mollusks in the superfamily Buccinoidea.This family has no subfamilies.-Genera:* Colubraria Schumacher, 1817* Cumia Bivona-Bernardi, 1838...
- Family ColumbellidaeColumbellidaeColumbellidae, common name the "dove snails" or "dove shells" are a family of minute to small sea snails, marine gastropod mollusks in the clade Neogastropoda.-Distribution:...
- Family FasciolariidaeFasciolariidaeFasciolariidae, common name the "tulip snails and spindle snails", is a family of small to large sea snails, marine gastropod mollusks in the superfamily Buccinoidea....
- Family NassariidaeNassariidaeNassariidae, common name nassa mud snails , or dog whelks , are a taxonomic family of small to medium-sized sea snails, marine gastropod mollusks in the clade Neogastropoda.-Shell description:...
- Family MelongenidaeMelongenidaeMelongenidae, the crown conchs, busycon whelks and their relatives, are a taxonomic family of large to very large marine gastropods in the clade Neogastropoda.- Taxonomy :Genera Busycon and Busycotypus were placed in Melongenidae...
- Family Buccinidae
- Superfamily MuricoideaMuricoideaMuricoidea is a taxonomic superfamily of predatory sea snails, marine gastropod mollusks in the clade Neogastropoda.This superfamily includes the murex snails, the chank snails, the true whelks, the dove snails, the crown conchs and busycon whelks, the spindle and tulip snails, the volutes and...
- Family MuricidaeMuricidaeMuricidae, common name murex snails or rock snails, is a large and varied taxonomic family of small to large predatory sea snails. With approximately 1,600 living species the Muricidae represent almost 10% of the Neogastropoda. Additionally, 1,200 fossil species have been recognised...
- Family BabyloniidaeBabyloniidaeBabyloniidae is a taxonomic family of predatory sea snails, marine gastropod mollusks within the superfamily Muricoidea.-Genera and species:Genera and species within the Babyloniidae are as follows:*Genus Acinopsis T.A...
- Family CostellariidaeCostellariidaeCostellariidae sometimes called the "ribbed miters" is a taxonomic family of minute to medium-sized predatory sea snails, marine gastropod mollusks. This family of snails is also sometimes referred to as Vexillum miters...
- Family CystiscidaeCystiscidaeCystiscidae is a taxonomic family of minute sea snails, marine gastropod mollusks or micromollusks.- Description :The shell is minute to large, either white, uniformly colored, or patterned; the surface is smooth, sculptured, or axially costate; the spire is flat to immersed, or low to tall; the...
- Family HarpidaeHarpidaeHarpidae, common name the harp snails, is a taxonomic family of large predatory sea snails, marine gastropod mollusks.- Subfamilies and genera :...
- Family MarginellidaeMarginellidaeMarginellidae, or the margin shells, are a taxonomic family of small, often colorful, sea snails, marine gastropod molluscs in the clade Neogastropoda.- Taxonomy :...
- Family MitridaeMitridaeMitridae, known as mitre shells, are a taxonomic family of sea snails, widely distributed marine gastropod molluscs in the clade Neogastropoda....
- † Family PholidotomidaePholidotomidaePholidotomidae is an extinct taxonomic family of predatory sea snails, marine gastropod mollusks....
- Family Pleioptygmatidae
- Family StrepsiduridaeStrepsiduridaeStrepsiduridae is a taxonomic family of predatory sea snails, marine gastropod mollusks in the superfamily Muricoidea, but its position is doubtful....
- Family TurbinellidaeTurbinellidaeTurbinellidae are a family of sea snails, marine gastropod mollusks in the order Neogastropoda.-Distribution:Species in this family are found world-wide, mostly in tropical shallow waters but some in deep waters.- Subfamilies :...
- Family VolutidaeVolutidaeVolutidae, common name volutes, are a taxonomic family of predatory sea snails that range in size from 9 mm to over 500 mm, marine gastropod mollusks...
- Family VolutomitridaeVolutomitridaeVolutomitridae is a family of sea snails, marine gastropod mollusks in the superfamily Muricoidea.-Genera:The family Volutomitridae contains six genera and about fifty described recent species:* Conomitra Conrad, 1865* Magdalemitra Kilburn, 1974...
- Family Muricidae
- Superfamily OlivoideaOlivoideaOlivoidea is a taxonomic superfamily of minute to medium-large predatory sea snails, marine gastropod mollusks in the clade Neogastropoda.-Taxonomy:...
- Family Olividae
- Family OlivellidaeOlivellidaeOlivellidae, common name the "dwarf olives", are a family of small predatory sea snails with smooth, shiny, elongated oval-shaped shells. The shells sometimes show muted but attractive colors, and may have some patterning....
- Superfamily PseudolivoideaPseudolivoideaPseudolivoidea is a taxonomic superfamily of sea snails, marine gastropod mollusks in the clade Neogastropoda.-Taxonomy:According to the taxonomy of the Gastropoda by Bouchet & Rocroi the superfamily Pseudolivoidea has two families:...
- Family PseudolividaePseudolividaePseudolividae is a taxonomic family sea snails, marine gastropod mollusks.-Taxonomy:According to the taxonomy of the Gastropoda by Bouchet & Rocroi the family Pseudolividae has no subfamilies.- Genera :...
- Family PtychatractidaePtychatractidaePtychatractidae is a taxonomic family sea snails, marine gastropod mollusks.- Taxonomy :According to the taxonomy of the Gastropoda by Bouchet & Rocroi the family Ptychatractidae has no subfamilies.- Genera :...
- Family Pseudolividae
- Superfamily ConoideaConoideaConoidea is a superfamily of predatory sea snails, marine gastropod mollusks within the suborder Hypsogastropoda. This superfamily is a very large group of marine mollusks, estimated at about 340 recent valid genera and subgenera, and considered by one authority to contain 4,000 named living species...
- Family Conidae
- Family ClavatulidaeClavatulidaeClavatulidae is a taxonomic family of sea snails, marine gastropod mollusks in the superfamily Conoidea.The family is not well differentiated morphologically....
- Family DrilliidaeDrilliidaeDrilliidae is a taxonomic family of small sea snails, marine gastropod mollusks in the superfamily Conoidea.This family has no subfamilies.-Description:...
- Family PseudomelatomidaePseudomelatomidaePseudomelatomidae is a family of predatory sea snails, marine gastropods included in the superfamily Conoidea and part of the Neogastropoda...
- Family StrictispiridaeStrictispiridaeStrictispiridae is a taxonomic family sea snails, marine gastropod mollusks.This family has no subfamilies.- Genera :Genera in the family Strictispiridae include:*Cleospira McLean, 1971** Cleospira bicolor...
- Family TerebridaeTerebridaeThe Terebridae, commonly referred to as auger shells or auger snails, are a group or taxonomic family of small to large predatory sea snails, marine gastropod mollusks....
- Family TurridaeTurridaeTurridae, , is a large taxonomic family of predatory sea snails, marine gastropod mollusks, that vary in size from minute to moderately large. With more than 4,000 species, the Turridae is the largest mollusk family and group of marine caenogastropods...
- Superfamily Cancellarioidea
- Family CancellariidaeCancellariidaeCancellariidae, common name the nutmeg snails or nutmeg shells, are a family of small to medium-large sea snails, marine gastropod mollusks in the clade Neogastropoda...
- Family Cancellariidae