Trochidae

Trochidae
	AshellofCoelotrochus tiaratus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Vetigastropoda
Order:	Trochida
Superfamily:	Trochoidea
Family:	Trochidae; Rafinesque,1815
Subfamilies
	See text
Synonyms
	Anisobranchia;

TheTrochidae,common nametop-snailsortop-shells,are afamilyof various sizedsea snails,marine gastropod molluscsin the subclassVetigastropoda.This family is commonly known as the top-snails because in many species the shell resembles a toyspinning top.

Taxonomy

The family Trochidae consists of the following subfamilies:^[1]

AlcyninaeWilliams, Donald, Spencer & Nakano, 2010
CantharidinaeGray, 1857
CarinotrochinaeS.-Q. Zhang, J. Zhang & S.-P. Zhang, 2020
ChrysostomatinaeWilliams, Donald, Spencer & Nakano, 2010
FossarininaeBandel, 2009
HalistylinaeKeen, 1958
KaiparathininaeB. A. Marshall, 1993
MonodontinaeGray, 1857
StomatellinaeGray, 1840
TrochinaeRafinesque, 1815
UmboniinaeH. Adams & A. Adams, 1854 (1840)

Additionally, the following genera have not yet been placed in any subfamily:

CallumbonellaThiele, 1924
†CoeloconulusNützel, 2012
EnidaA. Adams, 1860
†EocalliostomaO. Haas, 1953
†FagnastesiaS. N. Nielsen, Frassinetti & Bandel, 2004
†FalsotectusGründel, Keupp & Lang, 2017
†GuidoniaDe Stefani, 1880
†LithotrochusConrad, 1855
†TylotrochusKoken, 1896

Description

Shell

The length of an adult shell varies between 5 mm and 130 mm. There is also a wide variation in the shape of the shell. This goes from low auriform (ear-shaped) with a wideapertureto the long, slender conical forms of typical top shells. The shape may also be subglobose, turbinate or helicoid. Their height may vary between 3 mm and 152 mm. The shell contains only a fewwhorls.These have a highly variable exterior, ranging from smooth or glossy tosculptured.

The internal shell is nacreous. They have a brown, entirely corneous, circular, multispiraloperculumwhich fits theaperturesnugly. The operculum is formed of numerous gradually increasing whorls with a central nucleus. The aperture may be entire, tetragonal or rounded and has no reflectedlip.The peristome is generally not continuous.

These shells are often brightly colored and adorned with darker bands.

Species of the family Trochidae differ from those in the familyTurbinidaein having a corneous, never calcareous, operculum, which is always multispiral.^[2]

Internal anatomy

The animal is similar in general form to the Turbinidae. The top snails are characterized by some primitive traits: a heart with twoatria.They have retained only onekidneyand the secondosphradiumhas been lost in the course of evolution. The mantle cavity contains a single gill.

Along the side of the foot are three or more pairs of sensory epipodial tentacles. The head has a short, broad rostrum. The intertentacular lobes are simple or digitated, separate or united across the front, sometimes obsolete. The jaws are developed or absent.^[2]

Theradulais rhipidoglossate. The rhachidian teeth are always present and well-developed. The lateral teeth generally number 5 on each side, sometimes more numerous. The marginal teeth are narrow and very numerous.

Distribution and habitat

This family has a worldwide distribution in tropical, temperate and arctic waters. Members of this family are among the most common marine snails along the rocky shores of Europe. Most species in the family live either in theintertidal zoneor in the shallow subtidal zone, but some live in deeper water. They are usually abundant on solid, suitable substrates, like rocky shores and reefs.^[3]

Ecology

Life cycle

Species of the family Trochidae aredioecious,and thefertilizationoccurs externally by the release of eggs and sperm.^[3]Top snail eggs are laid individually or in gelatinous egg masses in the water. Individuals may hatch as free-swimming planktonic larvae or juvenile crawlers with a short swimming stage.^[3]

Feeding behavior

This family of snails consists ofherbivores,grazing with theirradulaeon rocky surfaces, feeding onalgaeand vegetabledetritus,and more rarely by filter-feeding, as observed in the genusUmbonium.^[3]

References

Williams S.T., Donald K.M., Spencer H.G. & Nakano T. (2010)Molecular systematics of the marine gastropod families Trochidae and Calliostomatidae (Mollusca: Superfamily Trochoidea).Molecular Phylogenetics and Evolution 54:783-809

^"WoRMS - World Register of Marine Species - Trochidae Rafinesque, 1815".marinespecies.org.Retrieved2022-11-22.
^^a ^bTryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
^^a ^b ^c ^dPoutiers, J. M. (1998). Gastropods in:FAO Species Identification Guide for Fishery Purposes: The living marine resources of the Western Central Pacific Volume 1.Seaweeds, corals, bivalves and gastropods. Rome, FAO, 1998. page 399.

External links

Miocene Gastropods and Biostratigraphy of the Kern River Area, California; United States Geological Survey Professional Paper 642This article incorporates text from this source, which is in thepublic domain.

[1] "WoRMS - World Register of Marine Species - Trochidae Rafinesque, 1815".marinespecies.org.Retrieved2022-11-22.

[Manual-2] Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia

[Poutiers-3] Poutiers, J. M. (1998). Gastropods in:FAO Species Identification Guide for Fishery Purposes: The living marine resources of the Western Central Pacific Volume 1.Seaweeds, corals, bivalves and gastropods. Rome, FAO, 1998. page 399.

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