Lingulata
Ancient brachiopods with tongue-shaped shells, little changed since the Cambrian.
The class Lingulata contains some of the oldest brachiopods, first appearing in the Cambrian period. They are also among the most morphologically conservative, having changed very little in shape from their earliest fossils to the present day. For instance, shells collected from living specimens in Japanese waters are nearly identical to those from Cambrian fossils. Their name comes from the Latin word for "tongue," referring to their tongue-shaped shells. Each shell is attached to a long, fleshy stalk called a pedicle, which the animal uses to burrow into sandy or muddy sediments. The Lingulata live in vertical burrows, with the front end facing upward and slightly exposed at the sediment surface. Cilia on the lophophore create a current for feeding and respiration through the lophophore and mantle cavity. The gut is complete and shaped like a J. Unlike most other shelled marine animals, which have calcium carbonate shells, Lingulata shells are made of calcium phosphate, protein, and chitin. As inarticulate brachiopods, their hinge mechanism is simple, lacking teeth and held together only by complex muscles. Both valves are roughly symmetrical. The genus *Lingula* (Bruguiere, 1797) may be the oldest animal genus with living species. It is primarily found in the Indo-Pacific and is harvested for food in Japan and Australia.
- classification
- Class of brachiopods
- shell_composition
- Calcium phosphate, protein, and chitin
- hinge_type
- Inarticulate (lacks teeth, held by complex musculature)
- habitat
- Vertical burrows in sandy or muddy sediments
- known_for
- Morphological conservatism; tongue-shaped shells; genus Lingula possibly the oldest animal genus with extant species
Lore & Background
Lingulata have tongue-shaped shells, hence the name from the Latin word for 'tongue,' with a long fleshy stalk called a pedicle used to burrow into sandy or muddy sediments. They inhabit vertical burrows with the anterior end facing up and slightly exposed at the sediment surface. The cilia of the lophophore generate a feeding and respiratory current through the lophophore and mantle cavity, and the gut is complete and J-shaped.
Reader's Guide
Lingulata are significant as one of the oldest brachiopod classes, with a fossil record extending back to the Cambrian period. Their extreme morphological conservatism—living specimens nearly identical to Cambrian fossils—makes them a key subject for studying evolutionary stasis. Unlike most shelled marine animals, their shells are composed of calcium phosphate, protein, and chitin, not calcium carbonate. As inarticulate brachiopods, their hinge mechanism lacks teeth and is held together only by complex musculature, with both valves roughly symmetrical. The genus Lingula, primarily Indo-Pacific, may be the oldest known animal genus still containing extant species and is harvested for human consumption in Japan and Australia. However, some researchers argue that the genus Lingula is not as old as commonly thought, introducing uncertainty into its status as a 'living fossil.'
Did You Know?
- Their shells are composed of calcium phosphate, protein, and chitin, unlike most shelled marine animals.
- The genus Lingula may be the oldest known animal genus that still contains extant species.
- Living Lingulata specimens found in waters around Japan are almost identical to ancient Cambrian fossils.
More in Other Invertebrates 1-22
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record