The extremely long upper lobe of the Thresher Shark's caudal fin is used to herd and stun small fishes upon which the shark feeds.
All the thresher sharks (Family Alopiidae) have an extremely long upper lobe of the caudal fin. The Thresher Shark can be recognised by its pointed, pectoral fins, white colouration of the body above the pectoral fins, and other fin characteristics. In life it is blue-grey dorsally and white ventrally.
Three species of thresher sharks are recorded from Australian waters. The Bigeye Thresher Alopias superciliosus, has very large eyes which extend onto the top surface of the head, and a deep groove which runs from behind the eyes to above the gill slits. The Pelagic Thresher, Alopias pelagicus, can be recognised by a combination of characters including fin shapes and colouration. The side of the body above the pectoral fin is dark.
The species occurs in coastal and oceanic waters. In Australia it occurs in temperate waters from the surface down to about 370 m.
The species has a widespread distribution in temperate and topical waters. In Australia it occurs from southern Queensland to Tasmania, around the south of the country and to the central coast of Western Australia.
The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums.
Feeding and diet
The elongate upper lobe of the tail is used to herd and stun small fishes upon which the shark feeds.
- Last, P.R. & J.D. Stevens. 1994. Sharks and Rays of Australia. CSIRO. Pp. 513, Pl. 1-84.