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
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.
Anatomy
Caudofo ...
(
Chaetodermomorpha).
[MolluscaBase eds. (2021). MolluscaBase. Solenogastres. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=2094 on 2021-04-14]
Some recent literature, and recent molecular evidence, indicates that the Aplacophora may be
polyphyletic
A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...
, and therefore these taxonomists divide Solenogastres and Caudofoveata into separate classes.
Morphology
In contrast to all other molluscan classes, the Aplacophora have no shell, and are instead covered by
aragonitic sclerites
A sclerite ( Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonl ...
(
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an ad ...
spicule
Spicules are any of various small needle-like anatomical structures occurring in organisms
Spicule may also refer to:
*Spicule (sponge), small skeletal elements of sea sponges
*Spicule (nematode), reproductive structures found in male nematodes ( ...
s), 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.
80% of solenogaster
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
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.
The radula grows by dividing existing teeth in two, or by adding a new tooth at the centre of the radular row.
The
salivary gland
The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary ...
s 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.
Development
During development many Solenogastres are covered by a spiny
scleritome
A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...
comprising spines or scale-like plates; this has been likened to the
halwaxiid scleritome.
Sclerite
A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...
s of ''
Epimenia
''Epimenia'' is a genus of cavibelonian solenogasters, a kind of shell-less, worm-like mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks ( ...
'' start out solid before developing a hollow stem that subsequently solidifies.
Ecology
Diet
Solenogasters feed on
cnidaria
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.
Their distinguishing feature is cnidocytes, specialized cells that ...
and
ctenophores
Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), a ...
, either sucking their bodily fluids or eating their tissue.
They do not use their radulae to rasp prey, as other molluscs do.
Phylogeny
There is some uncertainty regarding the phylogenetic position of the solenogasters. 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.
Indeed, some molecular datasets plot Solenogastres as an outgroup to Mollusca.
Families
*
Acanthomeniidae Salvini-Plawen, 1978
*
Amphimeniidae
Amphimeniidae is a family of solenogaster
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 ...
Salvini-Plawen, 1972
*
Apodomeniidae Kocot, Todt, N. T. Mikkelsen & Halanych, 2019
*
Dondersiidae
Dondersiidae is a family of molluscs
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 ...
Simroth, 1893
*
Drepanomeniidae
Drepanomeniidae is a family of solenogaster, , a kind of shell-less, worm-like, marine (ocean), marine mollusk.MolluscaBase eds. (2021). MolluscaBase. Drepanomeniidae Salvini-Plawen, 1978. Accessed through: World Register of Marine Species at: ht ...
Salvini-Plawen, 1978
*
Epimeniidae
Epimeniidae is a family of solenogaster, a shell-less worm-like mollusk. MolluscaBase eds. (2021). MolluscaBase. Epimeniidae Salvini-Plawen, 1978. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=tax ...
Salvini-Plawen, 1978
*
Gymnomeniidae
Gymnomeniidae is a family of molluscs
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 recognize ...
Odhner, 1920
*
Hemimeniidae
Hemimeniidae is a family of molluscs belonging to the order Neomeniamorpha
The Neomeniamorpha are one of the three taxonomic orders of solenogasters, shell-less, worm-like, marine mollusks.
It is considered an alternate representation for t ...
Salvini-Plawen, 1978
*
Heteroherpiidae
''Heteroherpia'' is a genus of solenogaster
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 Caudofovea ...
Salvini-Plawen, 1978
*
Imeroherpiidae
Imeroherpiidae is a family of solenogaster
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 Caudofoveat ...
Salvini-Plawen, 1978
*
Lepidomeniidae
Lepidomeniidae is a family of molluscs belonging to the order Pholidoskepia.
Genera:
* '' Lepidomenia'' Kowalevsky, 1883
* '' Nierstrassia'' Heath, 1918
* '' Tegulaherpia'' Salvini-Plawen, 1983
References
{{Taxonbar, from=Q20735729
Pholido ...
Pruvot, 1902
*
Macellomeniidae Salvini-Plawen, 1978
*
Meiomeniidae Salvini-Plawen, 1985
*
Neomeniidae Ihering, 1876
*
Notomeniidae Salvini-Plawen, 2004
*
Phyllomeniidae Salvini-Plawen, 1978
*
Proneomeniidae Mitchell, 1892
*
Pruvotinidae Heath, 1911
*
Rhipidoherpiidae Salvini-Plawen, 1978
*
Rhopalomeniidae Salvini-Plawen, 1978
*
Sandalomeniidae Salvini-Plawen, 1978
*
Simrothiellidae Salvini-Plawen, 1978
*
Strophomeniidae Salvini-Plawen, 1978
*
Syngenoherpiidae Salvini-Plawen, 1978
;Unassigned in Solenogastres
* ''
Pholidoherpia''
Salvini-Plawen, 1978
* ''
Rhabdoherpia''
Salvini-Plawen, 1978
;Synonyms:
* Superorder Aplotegmentaria (not monophyletic)
** Myzomeniidae
Thiele, 1894: synonym of
Dondersiidae
Dondersiidae is a family of molluscs
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 ...
Simroth, 1893
* Superorder Pachytegmentaria (not monophyletic)
** Parameniidae
Simroth, 1893: synonym of
Pruvotinidae Heath, 1911 (invalid: type genus a junior homonym)
** Pararrhopaliidae
Salvini-Plawen, 1972: synonym of
Pruvotinidae Heath, 1911
** Perimeniidae
Nierstrasz, 1908: synonym of
Pruvotinidae Heath, 1911
** Proneomenidae
Mitchell, 1892: synonym of
Proneomeniidae Mitchell, 1892
** Pruvotiniidae
Heath, 1911: synonym of
Pruvotinidae Heath, 1911 (incorrect original spelling)
** Solenopodidae
Koren & Danielssen, 1877: synonym of
Neomeniidae Ihering, 1876
** Wireniidae
Salvini-Plawen, 1978: synonym of
Gymnomeniidae
Gymnomeniidae is a family of molluscs
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 recognize ...
Odhner, 1920
References
Further reading
*
{{Commonscat
Mollusc classes