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Family Tonnidae - tun shells
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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 thin, globose, with a short spire and very inflated, large body whorl. Sculpture only spiral, of relatively flat ribs or cords. No axial varices. Periostracum a thin smooth sheet. Aperture broad and extensive. Anterior siphonal canal short, a U-shaped notch. Outer lip generally thin, sometimes reflected and denticulate, in aults only. Inner lip with a more or less developed, glazed callosity, usually covering the umbilicus. Columella sometimes twisted. Operculum absent in the adult. Head with a relatively short but extremely extensible snout. Cephalic tentacles elongate, usually bearing eyes on bulges of their outer bases. Foot very large and wide, moderately flat. Fleshy siphon long. Tropical and warm temperate, mainly living on sandy bottoms, often where seagrasses abound. Can quickly bury themselves completely in the sand, except for the tip of the fleshy siphon. Feeds mainly on holothurians, which are first paralysed by a salivary secretion containing sulphuric acid, then swallowed whole. Sexes separate, fertilization internal. Eggs laid in masses of broad, gelatinous ribbons. Free-swimming, planktonic stage very long, lasting 2 to 8 months. Occasionally collected for food in the Indo-Pacific. Shells often used as decorative items (Ref. 348). |
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Main Ref. |
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