Vermetidae

Vermetidae
Serpulorbis squamiger
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	clade Hypsogastropoda
Superfamily:	Vermetoidea
(unranked):	clade Littorinimorpha
Family:	Vermetidae Rafinesque, 1815
Genera
See text.

Vermetidae, common name the worm snails or worm shells, is a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Littorinimorpha.

The shells of the Vermetidae are extremely irregular, and do not resemble the average snail shell, hence the common name "worm shells" or "worm snails".

They 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 and so on. 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 3 shell layers, whereas the annelid worm tubes are dull inside and have only 2 shell layers.

Taxonomy

The following subfamilies have been recognized in the taxonomy of Bouchet & Rocroi of 2005

• Dendropomatinae Bandel & Kowalke, 1997
• Vermetinae Rafinesque, 1815

Genera

Genera within the family Vermetidae include:

• Dendropoma Mörch, 1861
• Novastoa Finlay, 1927
• Petaloconchus I. Lea, 1843
• Serpulorbis Sasso, 1827
• Spiroglyptus Daudin, 1800
• Vermetus Cuvier, 1800

References

• Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1
• R. Tucker Abbott, 1986. Seashells of North America, St. Martin's Press, New York