Updated: Oct 21, 2022
The Cookiecutter shark (Isistius brasiliensis), also commonly known as the Cigar shark, is a small dogfish shark that prefers warm oceanic waters, usually near islands. This shark prefers deep waters and has been recorded in waters as deep as 3.7km. It is a diurnal shark, meaning that it makes a nightly migration to the surface and then descends back down during the day. The Cookiecutter shark owes its name to the cookie shaped wounds it leaves in its prey. Funny fact that relative to the size of its body, Cookiecutter sharks have the largest teeth of all sharks. Moreover, Cookiecutter sharks glow greenish due to light-emitting organs in its skin. This green bioluminescence is the strongest known of all sharks and the glow continues even after the shark has been taken out of the water.
Anatomy and appearance of Cookiecutter sharks
The Cookiecutter shark is a small shark that has a long, cigar-shaped body with a rounded snout. At full maturity, it reaches a maximum length of 42cm for males and 56cm for females. It has large, green, oval eyes that are placed forward on its head. Behind its eyes are large spiracles, which lead to its respiratory systems to enable them to breath. The mouth is short and filled with 30 to 37 rows of teeth in the upper jaw and 25 to 31 rows of teeth in the lower jaw. The teeth in the upper jaw are narrow, small, straight, and have a smooth-edged cusp. The lower teeth are larger, wider, and serrated, while the bases of the teeth are locked together to create a saw-like edge. The pectoral fins are short and are four-sided. The two dorsal fins are placed near the end of the body. The second dorsal fin is a little bit larger than the first one. The pelvic fin is the largest of the fins on the body. There is no anal fin. The caudal fin is wide with no visible ventral notch. The body is a dark brown color with lighter counter shading on the underside.
Habitat of the Cookiecutter shark
The Cookiecutter shark inhabits all tropic and sub-tropical oceans and is most commonly found between the latitudes of 20°N and 20°S. It prefers warm water temperatures between 18-26°C. In the Atlantic, it has been documented to be in the Bahamas, southern Brazil, Sierra Leone, southern Angola, Cape Verde, Guinea, and South Africa. In the Indo-Pacific, it has been documented in Mauritius, New Guinea, Australia, Japan, and New Zealand. In the Pacific, it has been documented in Fiji, Hawaiian Islands, Galapagos, and Guadalupe Islands.
By Chris_huh - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2828112 The Cookiecutter shark is known to migrate diurnally, meaning that it migrates from the deep ocean to the upper water column at night. It spends the day at a depth of 1 to 3.5km. The cookie cutter shark migrates up to around 85 meters at night, and occasionally all the way up to the surface. It is most commonly found near islands, probably for reproductive and predatory reasons.