seen? This snail with a large, thin spherical shell is
rarely seen. They are usually found in sandy bottoms in deeper water
and thus living snails are rarely seen on the intertidal. Elsewhere,
they are found in sandy areas especially in seagrass meadows.
Features: 9-10cm. The shell is
thin but strong, nearly spherical with a short spiral and very large
shell opening. Usually with spiralling ridges on the surface. Adult
snails lack an operculum.
The Banded tun (Tonna sulcosa) is about 10cm with a rather
thick shell that has flat spiral ribs. It is creamy white with 3-4
broad spiralling brown bands. It is found on fine sand and muddy bottoms.
The Spotted tun (Tonna dolium) is about 13cm and found on find
sand and muddy bottoms.
Changi, Jan 10
|What do they eat? Mainly echinoderms
such as sea cucumbers and crustaceans. The snail first paralyses the
prey with a salivary secretion containing sulphuric acid before swallowing
it whole! The animal has a large foot and can crawl and burrow rapidly.
tuns: The egg mass is a wide gelatinous ribbon containing many small, transparent
eggs. The planktonic larvae take a very long time to develop, thus
some species are widely dispersed by ocean currents.
Human uses: It is sometimes
collected for food by coastal dwellers and the shell used as decorative
|Tun shell snails on Singapore shores
|Other sightings on Singapore shores
Chek Jawa, Jun 12
Photo shared by Loh Kok Sheng on flickr.
Cyrene, Aug 13
Photo shared by Loh Kok Sheng on his
by a hemit crab.
Cyrene, Aug 11
Tonnidae recorded for Singapore
from Tan Siong
Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The
Molluscs of Singapore.
Tonna sulcosa (Banded
Tonnidae on The Gladys Archerd Shell Collection at Washington
State University Tri-Cities Natural History Museum website: brief
fact sheet with photos.
the Gastropods section by J.M. Poutiers in the FAO Species Identification
Guide for Fishery Purposes: The Living Marine Resources of the
Western Central Pacific Volume
1: Seaweeds, corals, bivalves and gastropods on the Food and
Agriculture Organization of the United Nations (FAO) website.
- Tan Siong
Kiat and Henrietta P. M. Woo, 2010 Preliminary
Checklist of The Molluscs of Singapore (pdf), Raffles
Museum of Biodiversity Research, National University of Singapore.
- Abbott, R.
Tucker, 1991. Seashells
of South East Asia.
Graham Brash, Singapore. 145 pp.