Lingula (genus)
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Lingula Temporal range: Cambrian–Recent |
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| Lingula anatina, shell (top), full habitus (bottom) | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Brachiopoda |
| Class: | Lingulata |
| Order: | Lingulida |
| Family: | Lingulidae |
| Genus: |
Lingula Bruguière, 1791 |
| Type species | |
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Lingula anatina Lamarck, 1801 |
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| species | |
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| Synonyms | |
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Ligula, Ligularius, Lingularius, Pharetra |
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| External identifiers for Lingula | |
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| Encyclopedia of Life | 73305 |
| ITIS | 156762 |
| NCBI | 7571 |
| WoRMS | 235158 |
| Also found in: | |
Ligula, Ligularius, Lingularius, Pharetra
Lingula is a genus of brachiopods within the class Lingulata. Lingula or forms very close in appearance have existed possibly since the Cambrian. Like its relatives, it has two unadorned organo-phosphatic valves and a long fleshy stalk. Lingula lives in burrows in barren sandy coastal seafloor and feeds by filtering detritus from the water. It can be detected by a short row of three openings through which it takes in water (sides) and expels it again (middle).
A shell encloses the organs and other internal parts of the body, except for a long, fleshy stalk (or pedicle) that extends from the tail (or posterior) end of the shell. This shell has two nearly identical tan or bronze valves, that are often tinged greenish or bluegreenish. These are held together by muscles between them. The valves are secreted by two mantle folds, one on the dorsal and one on the ventral side of the body. The valves are composed of chitin, protein, and calcium phosphate and consist of about 50% organic material. The outer surface is covered by a thin glossy layer of protein called periostracum. The high organic content of the shell makes it somewhat soft and flexible. These valves are located on the dorsal and ventral surfaces of the animal. The front (or anterior) end of the shell has a squared off (or truncate) shape and the rear end tapers to a point where the stalk emerges. This point (called apex) is the earliest part of the valve. The shell of the young animal roughly remains the same, adding much material at the front and less at the sides. Many growth lines are visible, parallel to the margins of the shell. The valves widen slightly at the front end, forming a narrow opening (or gape), through which water is pumped in at the sides and out from the middle. The ventral valve is slightly longer and slightly more convex. The margin of the valves is fringed by chitinous tan colored bristle (or chaetae), short at the side of the valves, but much longer at the front where they assist in keeping open the access of the body cavity to the outside water. In death, the gape is closed and the bristles may be absent or short as they become brittle and darker in color when dry.
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Wikipedia