phylaBrachiopoda

Brachiopoda is a phylum of marine, sessile animals known as lamp shells. They have two shells, or valves, that enclose the body. Unlike many bivalves, brachiopod valves are oriented dorsal and ventral, with a hinge along the rear margin. The body is commonly attached to the substrate by a stalk called a pedicle, though some species are free-living.

Anatomy and feeding: Most brachiopods possess a lophophore, a crown of ciliated tentacles used for feeding and gas exchange. Water flows through the lophophore where food particles are captured and directed to the mouth. The shell is usually calcareous, composed of calcium carbonate, though some early and inarticulate forms show different shell material. Two major subgroups are articulate brachiopods, which have a toothed hinge and interlocking valves, and inarticulate brachiopods, which lack a toothed hinge.

Ecology and life habits: Brachiopods are filter feeders inhabiting marine environments from shallow shelves to deep seas. Most anchor to hard substrates by a pedicle, while a few species have reduced or absent pedicles. They range from small to several centimeters in size and show a broad geographic distribution, with modern representatives found worldwide, particularly in cooler and deeper waters.

Fossil record and significance: Brachiopods first appear in the early Cambrian and became abundant in the Paleozoic, providing a major component of fossil marine communities and serving as important index fossils for ancient environments. Although their diversity declined after the Permian extinction, a modest group of species persisted to the present, contributing valuable information to studies of evolution and paleoecology.