Syrinx - the world's largest snail
The Giant Whelk (Syrinx aruanus): Adult and juvenile shells. Egg Case of the Giant Whelk (Syrinx aruanus): beached and dried egg case here shown attached to a gorgonian (fan) coral. Shells of young (from the egg case) are also shown. Australia is home to the world’s largest snail – the giant whelk. This enormous marine gastropod can grow to a shell length of 70cm. They are predatory snails and feed on large tube-dwelling polychaete worms (of the genera Polyodontes, Loimia, Diopatra). Due to their popularity as ornaments or specimens, very large Syrinx are now rarely seen intertidally although juvenile specimens are often washed ashore after storms and cyclones in northern Australia. Mature females produce large (15cm) egg cases which they attach to rocks, shells or gorgonian corals. Within the egg case, the young snails develop in individual egg capsules, then eventually hatch and crawl away as juveniles. This type of life history is known as direct development (that is, the larvae are not released into the sea water). Direct developing molluscs such as these are subject to local extinction because there are no means of planktonic-stage re-seeding from other areas, and hence they warrant protection.
Syrinx occurs from the intertidal zone down to 50 metres water depth and has a range across the northern half of the Australian coastline extending into southern New Guinea and Indonesia.
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