The Short-tail stingray, Dasyatis brevicaudata, also known as the Smooth stingray, is the largest stingray in the world. It is a member of Dasyatidae, the stingray family. It is one of numerous species sometimes called “bull rays”.
The Short-tail stingray is found on the continental shelf around South Africa (from Cape Town to the Zambezi), Mozambique, Australia (from Shark Bay, around the southern coast and up to Maroochydore, southern Queensland) and New Zealand (mainly North Island and Chatham Islands, uncommon south of Cook Strait and rarely at the Kermadec Islands). It inhabits depths of up to 1541.99 ft (470 m).
The short-tail stingray is ovoviviparous. The diameter of its disk is up to 6 ft (2 m), its length (including tail) is up to 14 ft (4.3 m), and it weighs as much as 770 lb (350 kg). It is plain with a bluntly angular snout and pectoral disc with round tips, a thick-based tail shorter than the body, and with a small upper and a long lower caudal finfold, the lower not reaching the tail tip. The tail ends in a vertically flattened fin-like tip. The disc is smooth except for a large, slender thorn on the tail in front of the stings. There are often 2 stings, the front one small, the rear one considerably larger, which bear toxin glands. Its coloration is grey-brown or bluish-grey dorsally with a row of small, pale blue spots at each pectoral fin base, and white ventrally.
They are generally found on soft bottoms and feed on crabs, mantis shrimps, bivalves, polychaetes, crustaceans and conger eels. Its teeth are flattened and plate-like. It frequently raises its tail with barbs in a scorpion-like fashion when approached. Though it can inflict severe wounds, it is considered more inquisitive than aggressive. A short-tail stingray also killed TV star Steve Irwin.
In summer large numbers gather around the Poor Knights Islands in New Zealand. The reason for this is not understood but it is suspected to be for breeding.
Illustration by Dr Tony Ayling