Tonna sulcosa

Tonna sulcosa, common name banded tun, is a species of large sea snail, a marine gastropod mollusk in the family Tonnidae, the tun shells.

Description
Shells of Tonna sulcosa usually can reach a length of 50 - 125 mm, with a maximum of 153 mm. These medium-sized shells are quite strong, oval-globose, with 4 -5 moderately convex turns and flat ridges. The aperture is large, semi-circular, with reflected lip and long, sharp teeth.

The shell surface is white with 3 - 5 wide brown bands.

Thin shell is ovate and ventricose. Its ground color is whitish, with four or five distinct bands of a reddish fawn-color, rarely continued to the outer lip. There is only one upon the two whorls next above the lowest. The spire is brown at top, and is formed of six convex whorls, encircled by projecting, pretty narrow, equal, approximate, flattened ribs, a little more distant towards the upper part..They are separated by shallow furrows. Two of the upper whorls are chequered as it were by intersections of striae. The suture is a little flattened, and slightly channeled. The ovate aperture is white, colored with red at the bottom. The outer lip is arcuated, and presents externally a projecting margin, which is crenulated outwardly by the jutting of the ribs, undulated externally, and dentated within. The columella is twisted. And upon some specimens are observed several crenulations towards the base of the inner lip which partially covers the umbilicus. The periostracum is thin and reddish.

Distribution
This species is widespread in the tropical Indo-West Pacific region - from the Red Sea and the Indian Ocean to the Indo-China, the Philippines and Australia (Queensland and Western Australia).

Habitat
These benthic gastropods live on sandy bottoms in tropical environment at depths of 10 to 70 m.

Life cycle
Embryos develop into free-swimming planktonic marine larvae (trochophore) and later into juvenile veligers.