Solenogastres | |
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A preserved specimen of Epimenia verrucosa | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Solenogastres |
Orders | |
The Solenogastres (less often referred to as Neomeniomorpha), common name the solenogasters, are one class of small, worm-like, shell-less molluscs (Aplacophora), the other class being the Caudofoveata (Chaetodermomorpha). [1]
Some recent literature, and recent molecular evidence, indicates that the Aplacophora may be polyphyletic, and therefore these taxonomists divide Solenogastres and Caudofoveata into separate classes. [2]
In contrast to all other molluscan classes, the Aplacophora have no shell, and are instead covered by aragonitic sclerites (calcareous spicules), which can be solid or hollow. These spicules can be arranged perpendicular to one another within the cuticle to form a skeleton, or can stick up to form a palisade, or can lie flat against the cuticle. [3]
80% of solenogaster species have a radula, while in others it is secondarily lost. The radula may bear one or more teeth per row; where there is more than one tooth, there is no central radular tooth. [3] The radula grows by dividing existing teeth in two, or by adding a new tooth at the centre of the radular row. [3] The salivary glands are very elaborate, and are an important character for taxonomy. Next to the mouth they have a unique sense organ, the vestibulum.
The solenogastres do not have true ctenidia, although their gill-like structures resemble them. [4]
During development many Solenogastres are covered by a spiny scleritome comprising spines or scale-like plates; this has been likened to the halwaxiid scleritome. [5]
Sclerites of Epimenia start out solid before developing a hollow stem that subsequently solidifies. [6]
Solenogastres can be found in a diverse range of habitats across the world, from the coast to the deep ocean. [7]
Solenogastres feed on cnidaria and ctenophores, either sucking their bodily fluids or eating their tissue. [8] They do not use their radulae to rasp prey, as other molluscs do. [9]
There is some uncertainty regarding the phylogenetic position of the solenogastres. Traditionally considered to be the most basal molluscan group and the sister group to the Caudofoveata, alternatives to both of these statements have been proposed on various lines of evidence. [5] Indeed, some molecular datasets plot Solenogastres as an outgroup to Mollusca. [10]
However, there are cryptic species which are hard to delineate due to their being a lack of multiple morphological characteristics that are necessary. [11]
Aplacophora is a presumably paraphyletic taxon. This is a class of small, deep-water, exclusively benthic, marine molluscs found in all oceans of the world.
Proneomeniidae is a family of uncommon molluscs in the class Solenogastres.
Wirenia argentea is a species of marine mollusc of solenogastres in the family Gymnomeniidae.
Notomenia is a genus of solenogasters, shell-less, worm-like, marinemollusks. In this genus the animal bears non-mineralized sclerites. This genus is the sole representative of the family Notomeniidae, and has secondarily reduced its radula, which is vestigial.
The Cavibelonia are one of the four orders of solenogaster, a kind of shell-less, worm-like mollusk.
Macellomenia is a genus of solenogaster, and the only genus in its family.
Spiomenia is a genus of solenogaster, shell-less, worm-like, marine mollusks.
Plawenia a genus of solenogasters, shell-less, worm-like, marine mollusks.
Kruppomenia is a genus of solenogaster, a kind of shell-less, worm-like, marine mollusk.
Helicoradomenia is a genus of solenogasters, shell-less, worm-like mollusks.
Cyclomenia is a genus of solenogaster, a kind of shell-less, worm-like mollusk.
Rhopalomenia is a genus of solenogasters, shell-less, worm-like, marine mollusks.
Epimenia is a genus of cavibelonian solenogasters, a kind of shell-less, worm-like mollusks.
Epiherpia is a genus of solenogasters, shell-less, worm-like molluscs.
Alexandromenia is a genus of solenogaster, a kind of shell-less, worm-like mollusk.
Pruvotinidae is a diverse taxonomic family of cavibelonian solenogasters, shell-less, worm-like marine mollusks.
Rhopalomeniidae is a family of solenogaster,, a kind of shell-less, worm-like, marine mollusk.
Epimeniidae is a family of solenogaster, a shell-less worm-like mollusk.
Acanthomeniidae is a family of solenogaster, a shell-less worm-like mollusk.
Amphimeniidae is a family of solenogaster, a shell-less worm-like mollusk.