Cryptodonta

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Cryptodonta
Antipleuridae - Panenka bohemica.JPG
Panenka bohemica (Antipleuridae) from Czech Republic, at the National Museum (Prague)
Scientific classification
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Cryptodonta

Neumayr, 1884
Orders

The Cryptodonta are a nearly-extinct subclass of the bivalves. It contains a single extant order, Solemyida, while the Praecardiida are known only from fossils.

The valves of the shell are relatively thin and somewhat elongated. Unlike most other bivalves, species in this group have no hinge teeth on their shells. They have relatively primitive, "protobranchiate", gills. [1]

Taxonomy

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<span class="mw-page-title-main">Seashell</span> Hard, protective outer layers created by an animal that lives in the sea

A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beaches by beachcombers. The shells are empty because the animal has died and the soft parts have decomposed or been eaten by another animal.

<span class="mw-page-title-main">Bivalvia</span> Class of molluscs

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, bivalves have no head and they lack some usual molluscan organs, like the radula and the odontophore. The class includes the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. Shipworms bore into wood, clay, or stone and live inside these substances.

<span class="mw-page-title-main">Muricidae</span> Family of molluscs

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<span class="mw-page-title-main">Siphon (mollusc)</span> Anatomical structure which is part of the body of some aquatic molluscs

A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes: Gastropoda, Bivalvia and Cephalopoda.

<span class="mw-page-title-main">Tusk shell</span> Class of elephant tusk shell molluscs

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<span class="mw-page-title-main">Periostracum</span> Outermost layer of the shell in many shelled animals

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<span class="mw-page-title-main">Myida</span> Order of bivalves

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<span class="mw-page-title-main">Unionida</span> Order of bivalves

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<span class="mw-page-title-main">Nuculanida</span> Order of bivalves

Nuculanida is an order of very small saltwater clams, marine bivalve molluscs in the subclass Protobranchia.

<span class="mw-page-title-main">Manzanellidae</span> Extinct family of bivalves

Manzanellidae is a fossil family of bivalves, in the order Solemyida. They were previously considered containing fossil and recent members of Nucinellidae.

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<span class="mw-page-title-main">Protobranchia</span> Subclass of bivalves

Protobranchia is a subclass of bivalve molluscs. It contains the extant orders Nuculanida, Nuculida, and Solemyida.

<span class="mw-page-title-main">Fordilloidea</span> Extinct superfamily of bivalves

Fordilloidea is an extinct superfamily of early bivalves containing two described families, Fordillidae and Camyidae and the only superfamily in the order Fordillida. The superfamily is known from fossils of early to middle Cambrian age found in North America, Greenland, Europe, the Middle East, Asia, and Australia. Fordillidae currently contains two genera, Fordilla and Pojetaia each with up to three described species while Camyidae only contains a single genus Camya with one described species, Camya asy. Due to the size and age of the fossil specimens, Fordillidae species are included as part of the Turkish Small shelly fauna.

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<i>Panenka</i> (bivalve) Genus of bivalves

Panenka is a genus of fossil saltwater clams, marine bivalve molluscs in the family Praecardiidae. Like most bivalves, these molluscs were suspension feeders. They lived in the Devonian Period.

<span class="mw-page-title-main">Hinge teeth</span>

Hinge teeth are part of the anatomical structure of the inner surface of a bivalve shell, i.e. the shell of a bivalve mollusk. Bivalves by definition have two valves, which are joined together by a strong and flexible ligament situated on the hinge line at the dorsal edge of the shell. In life, the shell needs to be able to open slightly to allow the foot and siphons to protrude, and then close again, without the valves moving out of alignment with one another. To make this possible, in most cases the two valves are articulated using an arrangement of structures known as hinge teeth. Like the ligament, the hinge teeth are also situated along the hinge line of the shell, in most cases.

<span class="mw-page-title-main">Shell purse</span>

A shell purse is a type of coin purse that is made from whole or trimmed mollusk shells, especially from bivalve mollusc shells. These purses are of mainly novelty use and purchased as souvenirs of visits, etc. In the past, some were engraved or painted with floral or other decorations, sentimental messages, personal or place names. In many cases there was extra working of the shell, either grinding down and polishing to expose the mother of pearl or filing to form patterns such as criss-cross designs.

<span class="mw-page-title-main">Nucinellidae</span> Family of bivalves

Nucinellidae is a family of bivalves, in the order Solemyida. Its species are small and principally reside in deep-water environments. The species' average length is less than 5 millimetres (0.20 in), the largest species being Nucinella boucheti at a length of 25 millimetres (0.98 in). The family's characteristic features include large gills and reduced palps and their appendages; oval shells with few hinge teeth; they possess a single adductor muscle and one divided foot exhibiting papillae. The family contains two known genera: Huxleyia and Nucinella. Speaking of Nucinella, the genus' ligament system is of the simple arched type, lacking nymphae. Regarding the former, the system is "submerged" beneath its dorsal margin.

References

  1. Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 430. ISBN   0-03-056747-5.