The Vermetidae, the worm snails or worm shells, are a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Littorinimorpha. 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 shells; 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 tube worms, for example the Serpulidae, 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 in the taxonomy of Bouchet & Rocroi (2005) within the clade Littorinimorpha.

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 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 C 511: 59-138. . 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 Daudin, 1800 - type genusGofas, S. (2009). Vermetus Daudin, 1800. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138652 on 2010-08-05 Cerithiovermetus Bandel, 2006WoRMS (2009). Cerithiovermetus. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=394145 on 2010-08-05

† Laxispirinae † Laxispira Gabb, 1877 - Late Cretaceous, type genus of the subfamily

Dendropomatinae Dendropoma Mörch, 1861 - type genus of the subfamilyWoRMS (2009). Dendropoma Mörch, 1861. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2009) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138649 on 2010-08-05

Subfamily ? Bivonia Gray, 1842:WoRMS (2010). Bivonia Gray, 1842. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=225183 on 2010-08-05 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, 1971WoRMS (2009). Eualetes. Accessed through the World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=397074 on 2010-08-05 Magilina Vélain, 1877 Novastoa Finlay, 1926WoRMS (2009). Novastoa Finlay, 1926. Accessed through the World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=205769 on 2010-08-05 Petaloconchus I. Lea, 1843WoRMS (2009). Petaloconchus Lea, 1843. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2009) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138650 on 2010-08-05 Spiroglyptus Daudin, 1800"Spiroglyptus Daudin, 1800". ITIS, accessed 6 August 2010. Stephopoma Mörch, 1860WoRMS (2009). Stephopoma Mörch, 1860. Accessed through the World Register of Marine Species at http://marinespecies.org/aphia.php?p=taxdetails&id=224610 on 2010-08-05 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 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.