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Mollusca: Scaphopoda
Description
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Molluscs in a bilaterally symmetrical, tapering, tubular slightly curved shell and ciliated filamentous feeding structures which are known as captacula. The radula is well developed and mineralised to varying degrees. Shell of aragonite with an external chitinous layer. Foot modified for burrowing and associated with opopodial lobes or terminal disk. Eyes, osphradium and gills absent. (Slightly simplified from Lamprell and Healy, 1998.)
Comments
Inexperienced sorters might initially place scaphopods among the polychaetes, perhaps Serpulidae (since both have calcareous tubes). However, serpulid tubes are irregularly laid down and are fixed to a hard substrate while scaphopods have a distinctive, evenly-curved and tapering white calcareous tusk-shaped tube which is either smooth or with longitudinal ridges. The tube of polychaetes of the family Pectinariidae is the about the same shape as scaphopod tubes (and are oriented in the sediment in a similar way) but scaphopod shells are hard, white and calcareous whereas pectinariids have a fragile tube of cemented sediment particles which, when broken, reveals a segmented worm within. Breaking a scaphopod shell will probably also break the soft-bodied, unsegmented mollusc within.
Scaphopods are found in soft sediments. The Australian fauna comprises 108 species, a significant fraction of the 500-600 species known world wide.
References
Lamprell, K and Healy, JM. 1998. A revision of the Scaphopoda from Australian waters (Mollusca). Records of the Australian Museum Supplement 24, 1-189.
Lamprell, K and Healy, JM. 2001. Scaphopoda. In Wells, A and Houston, WWK (eds). Zoological Catalogue of Australia. Vol. 17.2. Mollusca: Aplacophora, Polyplacophora, Scaphopoda, Cephalopoda. CSIRO Publishing, Melbourne, pp. 85-128.
Palmer, CP and Steiner, G. 1998. Class Scaphopoda. Introduction. In Beesley, PL, Ross, GJB and Wells, A (eds), Fauna of Australia. Mollusca: The Southern Synthesis. Fauna of Australia Volume 5. CSIRO Publishing, Melbourne, pp. 431-438.
Steiner, G. 1998a. Class Scaphopoda. Order Dentaliida. In Beesley, PL, Ross, GJB and Wells, A (eds), Fauna of Australia. Mollusca: The Southern Synthesis. Fauna of Australia Volume 5. CSIRO Publishing, Melbourne, pp. 439-443.
Steiner, G. 1998b. Class Scaphopoda. Order Gadilida. In Beesley, PL, Ross, GJB and Wells, A (eds), Fauna of Australia. Mollusca: The Southern Synthesis. Fauna of Australia Volume 5. CSIRO Publishing, Melbourne, pp. 443-447.
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