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), commonly known as solenogasters, are a class of small, worm-like, shell-less molluscs (Aplacophora), the other class being the Caudofoveata (Chaetodermomorpha). [1]
Some recent literature and recent molecular evidence,[ when? ] indicates that the Aplacophora may be polyphyletic, and therefore some taxonomists may divide Solenogastres and Caudofoveata into separate classes. [2]
In contrast to many other mollusc classes, aplacophorans 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, 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 center of the radular row. [3] The salivary glands are very elaborate, and are an important characteristic for taxonomy. Next to the mouth they have a unique sense organ, the vestibulum.
Solenogastres do not have true ctenidia, though their gill-like structures may 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 some 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. [5] Some molecular datasets plot Solenogastres as an outgroup to Mollusca. [10] However, there are cryptic species which are hard to delineate due to there being a lack of multiple morphological characteristics. [11]
Caudofoveata is a small class within the phylum Mollusca, also known as Chaetodermomorpha. The class is often combined with Solenogastres and termed Aplacophora, but some studies have cast doubt on the monophyly of this group.
Aplacophora is a possibly 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.
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 Pholidoskepia are one of the three orders of solenogaster.
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.
Amphimeniidae is a family of solenogaster, a shell-less worm-like mollusk.