Lingulid

Lingulid refers to a member of the order Lingulida, a lineage of inarticulate brachiopods that includes some of the most long-lived fossils in the animal kingdom. Lingulids and their relatives form one of the oldest brachiopod groups, with a fossil record extending from the early Cambrian and continuing to the present day.

Morphology and anatomy: Lingulids are small, sessile bivalved organisms with two symmetrical shells. They lack the hinge teeth and sockets found in articulate brachiopods. The shell is primarily composed of calcium phosphate (apatite) rather than calcite, a characteristic that helps distinguish lingulids in the fossil record. A long pedicle projects from the body and anchors the animal in soft sediment. Inside, a simple mantle cavity houses a horseshoe-shaped lophophore used for filter feeding.

Ecology and behavior: Lingulids are benthic filter feeders that live buried in sandy or muddy substrates, often in shallow marine environments worldwide. They feed by drawing in water and filtering suspended particles with the lophophore. Their flexible pedicle allows adjustment within the sediment, helping them cope with sediment movement and water flow.

Fossil record and significance: Lingulids are notable for their extensive fossil record and relative morphological stability over hundreds of millions of years. They provide important insights into early brachiopod evolution and paleoecology. Today, a small number of living lingulids exist, most notably the genus Lingula, including species such as Lingula anatina.

Taxonomy: Lingulida is the order within the class Lingulata. Lingulids are inarticulate brachiopods, distinguishing them from the more common articulate brachiopods of other groups.