Unionid bivalve shell 1 : 無料・フリー素材/写真
Unionid bivalve shell 1 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Exterior of left valve (anterior is the left; posterior is to the right; dorsal is at top; ventral is at the bottom)Bivalves are bilaterally symmetrical molluscs having two calcareous, asymmetrical shells (valves) - they include the clams, oysters, and scallops. In most bivalves, the two shells are mirror images of each other (the major exception is the oysters). They occur in marine, estuarine, and freshwater environments. Bivalves are also known as pelecypods and lamellibranchiates.Bivalves are sessile, benthic organisms - they occur on or below substrates. Most of them are filter-feeders, using siphons to bring in water, filter the water for tiny particles of food, then expel the used water. The majority of bivalves are infaunal - they burrow into unlithified sediments. In hard substrate environments, some forms make borings, in which the bivalve lives. Some groups are hard substrate encrusters, using a mineral cement to attach to rocks, shells, or wood.The fossil record of bivalves is Cambrian to Recent. They are especially common in the post-Paleozoic fossil record.Seen here is a "freshwater mussel" - a modern species of freshwater bivalve. The brownish-colored material covering much of the shell is the periostracum, which is made of organic matter. I suspect that this is Amblema plicata, the threeridge clam. If anyone can confirm the species identification, one way or the other, please leave a comment, with evidence.Classification: Animalia, Mollusca, Bivalvia, Palaeoheterodonta, Unionoida, Unionidae |
| 撮影日 | 2021-05-02 22:42:06 |
| 撮影者 | James St. John |
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