Neritimorpha is a clade of

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

that contains around 2,000 extant species of sea snails, limpets,

freshwater snails Freshwater snails are gastropod mollusks that live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs t ...

land snails A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

and

slugs Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a sma ...

. This clade used to be known as the superorder Neritopsina.

Etymology

The clade’s name, Neritimorpha, is from the Ancient Greek νηρίτης (nērī́tēs 'Nerite') and μορφή (morphḗ 'form').

Description

Despite their relatively low diversity, with only around 2,000 species, neritomorphs have achieved a remarkable diversity of forms, resembling a smaller-scale version of the diversity achieved by Gastropoda as a whole. Terrestrial lifestyles have evolved at least three separate occasions in neritimorphs: the

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

Dawsonellidae and the

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

Helicinidae and

Hydrocenidae Hydrocenidae is a taxonomic family of minute land snails or cave snails with an operculum, terrestrial gastropod mollusks or micromollusks in the clade Cycloneritimorpha. Hydrocenidae are widespread across the Palearctis and Africa, but reach ...

. Neritimorphs also include the shellless,

slug Slug, or land slug, is a common name for any apparently shell-less Terrestrial mollusc, terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced ...

-like '' Titiscania''. In all modern neritomorphs except neritopsids, the inner walls of the

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called " ...

are resorbed. Unlike most other gastropods, neritomorphs typically have calcified opercula. There is no operculum in the shellless ''Titiscania'', and the Phenacolepadidae have a vestigial, non-calcified operculum that shows no postlarval growth. Geophorus romblonensis

Evolutionary history

Neritimorpha has an extremely rich geologic history, going back to early

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

. This clade has been considered to be a leftover of early gastropod diversification. Neritimorpha is the sister taxon of the Apogastropoda. The clade uniting neritimorphs and apogastropods has been called either Adenogonogastropoda or Angiogastropoda. All modern members of Neritimorpha are classified in the order

Cycloneritimorpha Cycloneritida (nerites and false-limpets) is an order of land snails, freshwater snails, and sea snails.MolluscaBase eds. (2020). MolluscaBase. Cycloneritida. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/a ...

. Neritopsoidea was the first of the four modern neritomorph superfamilies to diverge from the others.

1997 taxonomy

According to the taxonomy of the Gastropoda (Ponder & Lindberg, 1997) Neritopsina is a

superorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

in the subclass Orthogastropoda. The superfamily Palaeotrochoidea is contained within Neritopsina but its order placement is undetermined.

2005 taxonomy

The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdes A. & Warén A. 2005. ''Classification and nomenclator of gastropod families''. Malacologia: International Journal of Malacology, 47(1-2). ConchBooks: Hackenheim, Germany. . ISSN 0076-2997. 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278 categorizes Neritimorpha as a

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

. It is one of the 6 highest clades in Gastropoda. It contains the clades Cyrtoneritimorpha,

, as well as

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

Neritimorpha of uncertain position. Clades (and uncertain position taxa) in Neritimorpha include: * †

Neritimorpha of uncertain position * † clade Cyrtoneritimorpha * clade

Four extant superfamilies are recognised:

Helicinoidea Helicinoidea is a taxonomic superfamily of land snails that have an operculum. In other words, they are terrestrial operculate gastropod mollusks. They are in the order Cycloneritida and are quite closely related to the marine and freshwater ...

, Hydrocenoidea,

Neritoidea Neritoidea is a Taxonomy (biology), taxonomic Taxonomic rank, superfamily of mostly sea snails, nerites and their allies, marine (ocean), marine gastropod mollusc, mollusks in the order Cycloneritida (according to the Taxonomy of the Gastropoda ( ...

and Neritopsoidea.

In human society

Nerite snails are popular in the aquarium trade.

References

{{Taxonbar, from=Q18713253