July

Isistius brasiliensis Quoy & Gaimard, 1824 (Cookie-cutter Shark)

Common name: Cookie-cutter Shark (AMS I.28748-004)

Collected: Off Sydney, NSW in 1989 by Dr John Paxton using an Isaac Kidd Midwater Trawl at depth of 900m

Australian Museum, Sydney, Australia

EMu user since 2002

KE client since 1985

 

july1_small.gif The Cookie-cutter Shark is named after the cookie-shaped wounds that it leaves on the bodies of larger animals. It has small, erect teeth in the upper jaw and large triangular teeth in the lower jaw. It attaches itself to its prey with its suctorial lips and then spins to cut out a cookie-shaped plug of flesh from the larger animal.

In addition to plugs of flesh from larger animals, the Cookie-cutter Shark is also known to eat squid and there are even reports of this species leaving crater-marks on the sonar domes of submarines.

Closely related to the Cookie-cutter Shark, the Large Tooth Cookie-cutter Shark, Isistius plutodus, (shown below) is renowned for its impressive row of nineteen huge triangular teeth in the lower jaw - proportionately the largest of any shark species.

Another curious feature of the Large Tooth Cookie-cutter Shark is that its short snout and anteriorly positioned eyes probably give it binocular vision, no doubt to locate its next victim with precision.

july2_small.gif This specimen (AMS I.28748-004), a 363 mm long female shark, was trawled by the FV Teresa at a depth of about 100 metres off Newcastle, NSW in 1988. It was the first record of this species from Southern Hemisphere waters.

Images: S. Humphreys, C. Bento © Australian Museum