The Vermetidae, the worm snails or worm shells, are a taxonomic

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of small to medium-sized

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

s, marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

molluscs in the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

Littorinimorpha Littorinimorpha is a large order of snails, gastropods, consisting primarily of sea snails (marine species), but also including some freshwater snails ( aquatic species) and land snails ( terrestrial species).Bouchet P. & Rocroi J.-P. (Ed.); Frý ...

. The shells of species in the family Vermetidae are extremely irregular, and do not resemble the average snail shell, hence the common name "worm shells" or "worm snails". These snails usually grow cemented onto a hard surface, or cemented together in colonies.

Shell description

These snails do not have typical regularly coiled

gastropod shell The gastropod shell is part of the body of a Gastropoda, gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium s ...

s; instead, they have very irregular elongated tubular shells which are moulded to, and cemented to, a surface of attachment such as a rock or another shell. In the adult, the apertural part of the shell is usually free, with the opening directed upward. Some species have an operculum and some do not. Damaged sections of the shell can be sealed off by calcareous septa when necessary. Some vermetids are solitary, whereas others live in colonies, partially cemented together. The shells of species within this family vary greatly and can sometimes be extremely challenging to identify.

Comparison with annelid worm tubes

The empty calcareous tubes of certain marine

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

tube worms, for example the

Serpulidae The Serpulidae are a family of sessile, tube-building annelid worms in the class Polychaeta. The members of this family differ from other sabellid tube worms in that they have a specialized operculum that blocks the entrance of their tubes wh ...

, can sometimes be casually misidentified as empty vermetid shells, and ''vice versa''. The difference is that vermetid shells are shiny inside and have three shell layers, whereas the annelid worm tubes are dull inside and have only two shell layers.

Taxonomy

2005 taxonomy

The Vermetidae were recognized as the only family in the superfamily

Vermetoidea The Vermetoidea, the worm snails or worm shells, are a taxonomic superfamily of small to medium-sized sea snails, marine gastropod molluscs in the order Littorinimorpha.MolluscaBase (2019). MolluscaBase. Vermetoidea Rafinesque, 1815. Accessed th ...

in the taxonomy of Bouchet & Rocroi (2005) within the clade

. The following two subfamilies were recognized in the taxonomy of Bouchet & Rocroi (2005): Family Vermetidae Rafinesque, 1815 *Subfamily Vermetinae Rafinesque, 1815 *Subfamily Dendropomatinae Bandel & Kowalke, 1997 This classification of the Vermetoidea has been somewhat controversial. Studies, based on sperm ultrastructure, and on molecular data clearly place it within the clade Littorinimorpha. However, there are still a number of authors that place it within the superfamily Cerithioidea. The genera ''Campanile'' and ''Thylacodes'' form a clade that is

sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a family, familial relationship, it is sometimes used endearingly to r ...

to the Cerithioidea, as shown in a study by Lydeard et al. (2002).

2006 taxonomy

Bandel (2006)Bandel K. (2006). "Families of the Cerithioidea and related superfamilies (Palaeo-Caenogastropoda; Mollusca) from the Triassic to the Recent characterized by protoconch morphology - including the description of new taxa". ''

Freiberger Forschungshefte The Freiberger, also known as Franches-Montagnes, is a horse breed from Switzerland, from the Jura region, described as either a "heavy warmblood" or a "light coldblood". It was widely used as draft and pack horse in the Swiss army. It ...

'' C 511: 59-138
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established a new subfamily Laxispirinae as one of three subfamilies he recognized within the Vermetidae: *Subfamily Vermetinae Rafinesque, 1815 *Subfamily † Laxispirinae Bandel, 2006 *Subfamily Dendropomatinae Bandel & Kowalke, 1997

Genera

Genera within the family Vermetidae include: Vermetinae * ''

Vermetus ''Vermetus'' is a genus of sea snails, marine gastropod mollusks in the family Vermetidae, the worm snails or worm shells. The genus ''Vermetus'' is very ancient: it occurs in the fossil record from the Jurassic to the Quaternary (age range: ...

'' Daudin, 1800 - type genus * '' Cerithiovermetus'' Bandel, 2006 † Laxispirinae * † ''Laxispira'' Gabb, 1877 - Late Cretaceous, type genus of the subfamily Dendropomatinae * '' Dendropoma'' Mörch, 1861 - type genus of the subfamily Subfamily ? *'' Bivonia'' Gray, 1842: synonym of '' Dendropoma'' Mörch, 1861 (junior homonym of Bivonia Cocco, 1832 in Crustacea) * ''Ceraesignum'' Golding, Bieler, Rawlings & T. Collins, 2014 * ''Cupolaconcha'' Golding, Bieler, Rawlings & T. M. Collins, 2014 *'' Eualetes'' Keen, 1971 * ''Magilina'' Vélain, 1877 *'' Novastoa'' Finlay, 1926 *''

Petaloconchus ''Petaloconchus'' is a genus of sea snails, marine (ocean), marine gastropod mollusks in the family (biology), family Vermetidae, the worm snails or worm shells. Species Species within the genus ''Petaloconchus'' include: * ''Petaloconchus apak ...

'' I. Lea, 1843 *''Spiroglyptus'' Daudin, 1800 *'' Stephopoma'' Mörch, 1860 *'' Thylacodes'' Guettard, 1770, = '' Serpulorbis'' Sassi, 1827Bieler, R.; Rosenberg, G. (2015). Thylacodes aotearoicus (J. E. Morton, 1951). In: MolluscaBase (2015). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=598652 on 2015-07-17 * '' Thylaeodus'' Mörch, 1860 *''Tripsycha'' Keen, 1961 * ''Vermetidae incertae sedis'' * ''Vermitoma'' Kuroda, 1928

References

External links

* Powell A. W. B., ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979 * R. Tucker Abbott, 1986. ''Seashells of North America, St. Martin's Press, New York * Vaught, K.C. (1989). ''A classification of the living Mollusca''. American Malacologists: Melbourne, FL (USA). . XII, 195 pp. {{Taxonbar, from=Q3139330 Taxa named by Constantine Samuel Rafinesque