Some morphological and ecological observations were made on early crawling stage of Hemifusus ternatanus (GMELIN). A female spent 10 days to finish laying 59 capsules on the cement bottom of an experimental pond. The number of shells in a capsule ranges from 2 to 11. Hatchout takes place about one month later the capsule was laid. Newly hatched snail measures about 6 mm in shell (veliconcha) height, although there was a bias in size within 298 specimens came out from 58 capsules (Fig. 1). The smooth protoconch is followed by early teleoconch first sculptured axially and then radially (Fig. 2). Whorls are formed in 3 at 6-12 mm in shell height, 4 at 12-17 mm, and 5 at 24-30 mm. There was a slight sexual difference in shell shape even at the early crawling stage. A male of 10 mm already has a penis developed (Fig. 3). Cannibalism was observed before and after hatch-out. The animal was fed by clam. Only 14 individuals were survived out of 90 snails being put together in an aquarium, although they ate 95 Ruditapes and 32 Irus for 2 months. The size of the prey is that is enable to be seized and covered by the snail's foot.

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