The Solenogastres (less often referred to as Neomeniomorpha),
common name
In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
the solenogasters, are one class of small, worm-like, shell-less molluscs (Aplacophora), the other class being the
Caudofoveata (
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 appropriat ...
have a
radula
The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...
, 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
Halwaxiida or halwaxiids is a proposed clade equivalent to the older orders Sachitida He 1980 and Thambetolepidea Jell 1981, loosely uniting scale-bearing Cambrian animals, which may lie in the stem group to molluscs or lophotrochozoa. Some pala ...
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'' 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"), ...
, 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 Salvini-Plawen, 1972
*
Apodomeniidae Kocot, Todt, N. T. Mikkelsen & Halanych, 2019
*
Dondersiidae Simroth, 1893
*
Drepanomeniidae Salvini-Plawen, 1978
*
Epimeniidae Salvini-Plawen, 1978
*
Gymnomeniidae
Gymnomeniidae is a family of molluscs belonging to the order Pholidoskepia
The Pholidoskepia are one of the three orders of solenogaster.
It is considered an alternate representation for the class Solenogastres
The Solenogastres (less ofte ...
Odhner, 1920
*
Hemimeniidae Salvini-Plawen, 1978
*
Heteroherpiidae Salvini-Plawen, 1978
*
Imeroherpiidae Salvini-Plawen, 1978
*
Lepidomeniidae
Lepidomeniidae is a family of molluscs belonging to the order Pholidoskepia
The Pholidoskepia are one of the three orders of solenogaster.
It is considered an alternate representation for the class Solenogastres
The Solenogastres (less oft ...
Pruvot, 1902
*
Macellomeniidae Salvini-Plawen, 1978
*
Meiomeniidae Salvini-Plawen, 1985
*
Neomeniidae Ihering, 1876
*
Notomeniidae
Notomeniidae is a family of solenogaster, a kind of shell-less, worm-like, marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Aroun ...
Salvini-Plawen, 2004
*
Phyllomeniidae Salvini-Plawen, 1978
*
Proneomeniidae
Proneomeniidae is a family of uncommon molluscs in the class Solenogastres
The Solenogastres (less often referred to as Neomeniomorpha), common name the solenogasters, are one class of small, worm-like, shell-less molluscs (Aplacophora), the ...
Mitchell, 1892
*
Pruvotinidae
''Pruvotinidae'' is a diverse taxonomic family of cavibelonian solenogasters, shell-less, worm-like marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as mollu ...
Heath, 1911
*
Rhipidoherpiidae
Rhipidoherpiidae is a family of solenogaster, a kind of shell-less, worm-like, marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). A ...
Salvini-Plawen, 1978
*
Rhopalomeniidae
Rhopalomeniidae is a family of solenogaster, , a kind of shell-less, worm-like, marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). ...
Salvini-Plawen, 1978
*
Sandalomeniidae Salvini-Plawen, 1978
*
Simrothiellidae
''Kruppomenia'' is a family of solenogaster, a kind of shell-less, worm-like, marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks () ...
Salvini-Plawen, 1978
*
Strophomeniidae
Strophomeniidae is a family of solenogaster, a kind of shell-less, worm-like, marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Ar ...
Salvini-Plawen, 1978
*
Syngenoherpiidae
Syngenoherpiidae 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 Caudofove ...
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 Simroth, 1893
* Superorder Pachytegmentaria (not monophyletic)
** Parameniidae
Simroth, 1893: synonym of
Pruvotinidae
''Pruvotinidae'' is a diverse taxonomic family of cavibelonian solenogasters, shell-less, worm-like marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as mollu ...
Heath, 1911 (invalid: type genus a junior homonym)
** Pararrhopaliidae
Salvini-Plawen, 1972: synonym of
Pruvotinidae
''Pruvotinidae'' is a diverse taxonomic family of cavibelonian solenogasters, shell-less, worm-like marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as mollu ...
Heath, 1911
** Perimeniidae
Nierstrasz, 1908: synonym of
Pruvotinidae
''Pruvotinidae'' is a diverse taxonomic family of cavibelonian solenogasters, shell-less, worm-like marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as mollu ...
Heath, 1911
** Proneomenidae
Mitchell, 1892: synonym of
Proneomeniidae
Proneomeniidae is a family of uncommon molluscs in the class Solenogastres
The Solenogastres (less often referred to as Neomeniomorpha), common name the solenogasters, are one class of small, worm-like, shell-less molluscs (Aplacophora), the ...
Mitchell, 1892
** Pruvotiniidae
Heath, 1911: synonym of
Pruvotinidae
''Pruvotinidae'' is a diverse taxonomic family of cavibelonian solenogasters, shell-less, worm-like marine mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as mollu ...
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 belonging to the order Pholidoskepia
The Pholidoskepia are one of the three orders of solenogaster.
It is considered an alternate representation for the class Solenogastres
The Solenogastres (less ofte ...
Odhner, 1920
References
Further reading
*
{{Commonscat
Mollusc classes