The Vermetidae, the worm snailsorworm shells, are a taxonomicfamily of small to medium-sized sea snails, marinegastropodmolluscs in the cladeLittorinimorpha.[1] 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.
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.
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.
This classification of the Vermetoidea has been somewhat controversial. Studies, based on sperm ultrastructure,[2] and on molecular data[3] clearly place it within the clade Littorinimorpha. However, there are still a number of authors[4][5][6] 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).[7]
^J.M. Healy (1988). "Sperm morphology in Serpulorbis and Dendropoma and its relevance to the systematic position of the Vermetidae (Gastropoda)". Journal of Molluscan Studies. 54 (3): 295–308. doi:10.1093/mollus/54.3.295.
^D. Colgan, W.F. Ponder & P.E. Eggler (2000). "Gastropod evolutionary rates and phylogenetic relationships assessed using partial 28s rDNA and histone H3 sequences". Zoologica Scripta. 29: 29–63. doi:10.1046/j.1463-6409.2000.00021.x. S2CID84342267.
^K. Bandel & T. Kowalke (1997). "Cretaceous Laxispira and a discussion on the monophyly of vermetids and turritellids (Caenogastropoda, Mollusca)". Geologica et Palaeontologica. 31: 257–274.
^"Earliest known (Campanian- members of the Vermetidae, Provannidae and Litiopidae (Cerithioidea, Gastropoda) and a discussion on their possible relationships". Mitteilungen aus dem geologisch-Paläontologischen Institut, Universität Hamburg. 84: 209–218. 2000.
^T. Kowalke (1998). "Bewertung protoconchmorphologischer Daten basaler Caenogastropoda (Cerithiimorpha und Littorinimorpha) hinsichtlich ihrer Systematik und Evolution von der Kreide bis rezent". Berliner Geowissenschaftliche Abhandlungen, Ser; e (Palaeobiologie). 27: 1–121.
^C. Lydeard, W.E. Holznagel, M. Glaubrecht & W.F. Ponder (2002). "Molecular phylogeny of a circumglobal, diverse gastropod superfamily (Cerithioidea, Mollusca, Caenogastropoda): pushing the deepest phylogenetic limits of mitochondrial LSU r DNA sequences". Molecular Phylogenetics and Evolution. 22 (3): 399–406. doi:10.1006/mpev.2001.1072. PMID11884164.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ abcBandel 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. [1].
^WoRMS (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
^WoRMS (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
