''Pododesmus patelliformis'', the ribbed saddle-oyster, is a species of

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusc 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 esti ...

in the family Anomiidae. It is found in the north east Atlantic Ocean.

Description

This oyster has a thin asymmetric shell up to four centimetres in length which is white, sometimes with brown markings. The outline is roughly circular and the beaks are central but set back from the margin. The upper valve is sculptured with up to sixty weak radial riblets, and the inside is glossy white or tinged yellowish-green with two distinct, furrowed muscle scars on the upper valve. The lower valve is flat, thin, transparent and

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

and has one muscle scar.Conchological Society of Great Britain and Ireland
/ref>Marine Bivalve Shells of the British Isles
/ref>

Distribution

This species occurs on the north west fringes of Europe extending from Norway to the Mediterranean Sea. It lives on coarse sand and gravel, attached to rocks or other shells by its byssus. It is found in intertidal zones and down to about two hundred feet. It is sometimes confused with ''P. squama'' and in fact Smith & Heppell (1991) considered them to be the same species.

Ecology

Older specimens of the ribbed saddle-oyster are usually covered by

tubeworms A tubeworm is any worm-like sessile invertebrate that anchors its tail to an underwater surface and secretes around its body a mineral tube, into which it can withdraw its entire body. Tubeworms are found among the following taxa: * Annelida, the ...

and sponges.The Marine Flora & Fauna of Norway
/ref> Other species often found living in the same vicinity include the parchment worm '' Chaetopterus variopedatus'', encrusting

red algae Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

, the polychaete worm '' Pomatoceros triqueter'' and the fan worm '' Sabella pavonina''. Scattered colonies of '' Alcyonium digitatum'' may be nearby along with the hydroid '' Bougainvillia ramosa'', the

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

Balanus balanus ''Balanus balanus'' is a species of acorn barnacle in the Balanidae family. It is native to the colder seas of the northern hemisphere. Description Unlike most crustaceans, barnacles are unable to move from place to place. Cement glands near the ...

'', the hermit crab ''

Pagurus bernhardus ''Pagurus bernhardus'' is the common marine hermit crab of Europe's Atlantic coasts. It is sometimes referred to as the common hermit crab or soldier crab. Its carapace reaches long, and is found in both rocky and sandy areas, from the Arctic wa ...

'' and the squat lobster '' Munida rugosa''.European Environment Agency
/ref>

References

{{Taxonbar, from=Q3803644 Anomiidae Molluscs described in 1761 Taxa named by Carl Linnaeus