''Testudinalia testudinalis'', common name the common tortoise limpet, 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 ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a

true limpet The Patellogastropoda, common name true limpets and historically called the Docoglossa, are members of a major phylogenetic group of marine gastropods, treated by experts either as a clade or as a taxonomic order. The clade Patellogastropoda ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

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 Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Lottiidae Lottiidae is a family of sea snails, specifically true limpets, marine gastropod mollusks in the superfamily Lottioidea and the clade Patellogastropoda (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Subfamilies 20 ...

, one of the families of true limpets. It is commonly known as the plant limpet or tortoiseshell limpet.The Marine Flora & Fauna of Norway
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Description

''T. testudinalis'' has a low domed shell, oval in outline. It can grow to up to 30 x 24 x 10 mm but typically is about half this size. The apex is towards the anterior of the shell and fine ridges radiate from it. The shell is banded with brown and white. The mantle is the part of the body wall immediately under the shell and at the edges it is curled round to form a collar. The foot is broad and oval. The head bears two sensory tentacles with a tiny black eye at the base of each.

Distribution and habitat

''T. testudinalis'' occurs in northern regions of both the Pacific and Northwest Atlantic Oceans and in European waters. It is found in the neritic zone from low water mark down to a depth of about fifty metres. It is usually found on stones and boulders, especially those encrusted with red crustose algae such as ''

Lithothamnion ''Lithothamnion'' is a genus of thalloid red alga comprising 103 species. Its members are known by a number of common names.Recorded common names are griuán, maërl, punalevä-suku, stenhinna and maerl. The monomerous, crustose thalli are compos ...

''.Marine Species Identification Portal
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Biology

Red eggs are laid in a sheet in the spring and the larvae are

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

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References

* Ziegelmeier, E. (1966). ''Die Schnecken (Gastropoda Prosobranchia) der deutsche Meeresgebiete und brackigen Küstengewässer he Gastropoda Prosobranchia from the German seas and brackish coastal waters'' Helgol. Wiss. Meeresunters. 13: 1-66 * Hayward, P.J.; Ryland, J.S. (Ed.) (1990). ''The marine fauna of the British Isles and North-West Europe: 1. Introduction and protozoans to arthropods.'' Clarendon Press: Oxford, UK. . 627 pp. * 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. * 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): 56 * de Kluijver, M.J.; Ingalsuo, S.S.; de Bruyne, R.H. (2000). ''Macrobenthos of the North Sea'' D-ROM 1. Keys to Mollusca and Brachiopoda. World Biodiversity Database CD-ROM Series. Expert Center for Taxonomic Identification (ETI): Amsterdam, The Netherlands. . 1 cd-rom pp. * 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 * Trott, T.J. 2004. ''Cobscook Bay inventory: a historical checklist of marine invertebrates spanning 162 years.'' Northeastern Naturalist (Special Issue 2): 261 - 324. * Kantor Yu.I. & Sysoev A.V. (2006) ''Marine and brackish water Gastropoda of Russia and adjacent countries: an illustrated catalogue.'' Moscow: KMK Scientific Press. 372 pp. + 140 pls. page(s): 22 * Nakano & Ozawa (2007). ''Worldwide phylogeography of limpets of the order Patellogastropoda: Molecular, morphological and palaeontological evidence.'' Journal of Molluscan Studies 73(1) 79-99. {{DEFAULTSORT:Testudinalia Testudinalis Lottiidae Gastropods described in 1776 Taxa named by Otto Friedrich Müller