''Addisonia excentrica'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

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 es ...

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 ...

Addisoniidae Addisoniidae is a family of sea snails, deepwater true limpets, marine gastropod mollusks in the clade Vetigastropoda Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. ...

Distribution

This species can be found in European waters and in the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

Description

The maximum recorded

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 ...

length is 20.3 mm.Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". '' PLoS ONE'' 5(1): e8776. doi:10.1371/journal.pone.0008776. The size of the ovate shell varies between 8 mm and 20 mm. It is thin and whitish. 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, ...

presents an appearance as if an embryonic tip (perhaps spiral) had fallen and been replaced by a peculiarly blunt ovate apex, which in the young shell is nearly marginal, posterior and to the left of the middle line, but in the adult is considerably within the margin, curved downward and backward and much more asymmetrical. The

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

of the shell shows faint grooves radiating from the (smooth) apex and reticulated by the stronger concentric lines of growth, beside which the extremely inflated arch of the back is somewhat obscurely concentrically waved. The shell has a polished appearance over the sculpture. The thin margins are sharp. The interior of the shell is smooth and somewhat polished. The scar of the pedal muscle is narrow and at a considerable distance within the margin. The anterior ends of the scar are enlarged and hooked backward on their inner edges. These ends are connected by a line broadly arched forward and marking the attachments of the mantle to the shell over the head.G.W. Tryon (1889) Manual of Conchology vol. XII p. 140 (described as ''Addisonia paradoxa'')
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Habitat

Minimum recorded depth is 91 m. Maximum recorded depth is 1170 m.

References

* McLean, J. H. 1985. ''The Archaeogastropod family Addisoniidae Dall 1882'': Life habit and review of species. Veliger 28: 99–108 * Rosenberg, G. 1992. ''Encyclopedia of Seashells''. Dorset: New York. 224 pp. page(s): 31 * Dantart L. & Luque A. A. (1994). ''Cocculiniformia and Lepetidae (Gastropoda: Archaeogastropoda) from Iberian waters''. Journal of Molluscan Studies 60 (3): 277-313 * Turgeon, D.D., et al. 1998. ''Common and scientific names of aquatic invertebrates of the United States and Canada''. American Fisheries Society Special Publication 26-page(s): 59 * Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification''. Collection Patrimoines Naturels, 50: pp. 180–213 * Roldan E. & Luque A. (2010) ''The ecology, biology and taxonomy of Addisonia excentrica (Tiberi, 1855) (Cocculiniformia: Addisoniidae) from southern Spain''. Journal of Molluscan Studies 76:201–210

External links

Serge GOFAS, Ángel A. LUQUE, Joan Daniel OLIVER,José TEMPLADO & Alberto SERRA (2021) - The Mollusca of Galicia Bank (NE Atlantic Ocean); European Journal of Taxonomy 785: 1–114
* {{DEFAULTSORT:Addisonia Excentrica Addisoniidae Gastropods described in 1855