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Brachiopod. Brachiopods (/ ˈbrækioʊˌpɒd /), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection.
The stalk (or pedicle) is a long white extension of the body, that emerges at the apex from between the valves, and not, as in articulate brachiopods, from a special opening in the dorsal valve. At the rear end, that is deepest in the sea bed, the skin (or epithelium ) secretes a glue-like mucus that binds to the substrate's particles, thus ...
Lingulata shells are composed of a combination of calcium phosphate, protein and chitin. This is unlike most other shelled marine animals, whose shells are made of calcium carbonate. The Lingulata are inarticulate brachiopods, so named for the simplicity of their hinge mechanism. This mechanism lacks teeth and is held together only by a complex ...
Pentamerida is an order of biconvex, impunctate shelled, articulate brachiopods that are found in marine sedimentary rocks that range from the Middle Cambrian through the Devonian. [ 1 ] Pentamerids are characterized by a short hinge line where the two valves articulate, inner areas above the hinge line that slope inwardly from the beak of each ...
Orthida is an extinct order of brachiopods which appeared during the Early Cambrian period and became very diverse by the Ordovician, living in shallow-shelf seas.Orthids are the oldest member of the subphylum Rhynchonelliformea (Articulate Brachiopods), and is the order from which all other brachiopods of this group stem. [1]
Evolution of brachiopods. The origin of the brachiopods is uncertain; they either arose from reduction of a multi-plated tubular organism, or from the folding of a slug-like organism with a protective shell on either end. Since their Cambrian origin, the phylum rose to a Palaeozoic dominance, but dwindled during the Mesozoic.
Linguliformea. Linguliformea is a subphylum of inarticulate brachiopods. [1] These were the earliest of brachiopods, ranging from the Cambrian into the Holocene. They rapidly diversified during the Cambrian into the Ordovician, but most families became extinct by the end of the Devonian. The articulation in these brachiopods is lacking.
Rhynchonelliformea. Rhynchonelliformea is a major subphylum and clade of brachiopods. It is roughly equivalent to the former class Articulata, which was used previously in brachiopod taxonomy up until the 1990s. These so-called articulated brachiopods have many anatomical differences relative to "inarticulate" brachiopods of the subphyla ...