The eastern mudsnail, ''Ilyanassa obsoleta'', is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of sea snail, a marine gastropod

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the

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

Nassariidae, the nassa mud snails.MolluscaBase eds. (2021). MolluscaBase. Ilyanassa obsoleta (Say, 1822). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=467490 on 2021-09-04

Shell description

This species has a small

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

with a slightly rough exterior, because the surface has intersecting weak spiral and axial ribs. The shell has an oval

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

with a small notch or siphonal canal at the anterior end. The aperture has a smooth inner lip with a partial shield, and the outer lip is thin and smooth. The exterior of the shell is chalky white, but it is covered by a very dark brown, closely adhering periostracum, except in areas of the shell where the periostracum has been eroded. The

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

of the shell is almost always eroded, and the shell is often quite damaged by the acidic properties of the mud in which the animal lives. The maximum shell length is a little more than one inch, or about 28 mm.

Distribution

The indigenous distribution of this western

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

species is from

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

in the

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. The nonindigenous distribution includes the West Coast of the United States.

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

. 2008. Nassarius obsoletus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Accessed 29 October 2008.

Ecology

Habitat

This snail is very common on mud flats in the intertidal and shallow subtidal zones, in

sounds In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...

and inlets.

Feeding habits

This species is a detritus feeder, eating whatever is found in the film on top of the mud where it lives, including many microscopic marine plants.

References

;Notes * Cernohorsky W. O. (1984). Systematics of the family Nassariidae (Mollusca: Gastropoda). Bulletin of the Auckland Institute and Museum 14: 1-356. * Brunel, P., L. Bosse, & G. Lamarche. (1998). Catalogue of the marine invertebrates of the estuary and Gulf of St. Lawrence. Canadian Special Publication of Fisheries and Aquatic Sciences, 126. 405 p.

External links

* Goulding MQ. 2009
''Cell Lineage of the Ilyanassa Embryo: Evolutionary Acceleration of Regional Differentiation during Early Development''
PLoS ONE 4(5): e5506.
Blakeman Smith, Journal of Molluscan Studies

Kelaher et al., J Experimental Marine Biology and Ecology
*
Yang, Y.; Abalde, S.; Afonso, C. L.; Tenorio, M. J.; Puillandre, N.; Templado, J.; Zardoya, R. (2021). Mitogenomic phylogeny of mud snails of the mostly Atlantic/Mediterranean genus Tritia (Gastropoda: Nassariidae). Zoologica Scripta
{{Taxonbar, from1=Q3142539, from2=Q61697812 Ilyanassa Gastropods described in 1822