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Family Vermetidae - worm shells
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Order |
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Class |
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Gastropoda |
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No. of Genera in Ref. |
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No. of Species in Ref. |
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Environment |
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Fresh : No |
Brackish : No |
Marine : Yes |
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First Fossil Record |
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Remark |
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Shell long, usually irregularly coiled or even disjunct and resembling a worm tube, but composed of 3 layers, with the inner one porcelaneous. Shell permanently attached to a hard substrate. First whorls coiled around an axis at a 90 degree angle to that of the larval shell. Sculpture weak, longitudinal or transverse, and irregular. Aperture rounded, sharp-edged, without a siphonal canal. Operculum horny, spiral, sometimes absent. Head with short tentacles bearing eyes at their outer bases. Foot small. Mostly in warm-temperate or tropical, intertidal, and shallow water environments. Attached to rocks, corals and other shells, sometimes corroding the substrate and partly or even completely embedded in it. Some species occur in dense masses and may be important contributors to reef-building. Filter-feeding animals, extracting tiny planktonic organisms or detrital fragments from the water by means of 2 different ways of capture. In the ciliary feeding method, food is swept in the mantle cavity with the incurrent water, caught on the gill filaments, wrapped in mucous and carried along ciliary tracts to the mouth. In the mucous feeding method, a secretory gland of the foot produces sticky mucous strings or nets that are released in the water to entangle the food, then drawn back and swallowed. Sexes separate, fertilization internal, presumably by means of water-borne sperm. Eggs brooded by the female, hatching as crawling juveniles, or as free-swimming larvae for a short planktonic stage. Worm shells are traditionally used as food by some coastal populations of the area, notably in Polynesia. Though they may be regularly collected, they generally appear in markets only rarely (Ref. 349). |
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