Tiger shark - Galeocerdo cuvier
WHAT TO LOOK FOR
A large shark with an extremely wide, blunt snout and a caudal keel.
Varies from brownish, olive, gray to black above; pale gray, dirty yellow, pale gray or white below. Young sharks have tiger-like vertical dark bars, but as the sharks age the marks fade and they are usually absent in adults.
Most individuals encountered by divers range between 11 and 14 ft [3.4 to 4.3 m] in length. Males mature at 7.4 to 9.5 ft [2.26 to 2.9 m], and reach a length of at least 12.1 ft [3.7 m]. Females mature between 8.2 and 11.5 ft [2.5 and 3.5 m] and reach a length of more than 18 ft [5.5 m]. One large female caught in 1957 was 24 ft [7.4 m] and weighed 3,110 lbs [1,414 kg], and there is an unverified report of a 30 ft [9.1 m] individual.
The teeth in both jaws are identical: heavy cockscomb-shaped cutting teeth resembling diagonally positioned blades. The coarse serrations of the teeth have fine secondary serrations.
Although the shark occurs off oceanic islands and has been photographed at a depth of 1,007 ft [305 m], it is regarded as a coastal species. The shark tolerates a wide variety of marine habitats and may be found in estuaries, turbid waters at river mouths, around jetties and wharves, coral atolls and lagoons.
Circumglobal in tropical and warm temperate seas.
Prey – The tiger shark is omnivorous; it may attempt to consume virtually anything that can fit between its jaws. It feeds on bony fish, sharks, rays, marine turtles, marine mammals, sea snakes, sea birds, crustaceans, octopus and squid, jellyfish, carrion and garbage.
Reproduction – Ovoviviparous. Gestation is slightly over a year and the litters are large: 10 to 82 pups. Pups, born at a length of 20 to 30 inches [51 to 76 cm], double in length within the first year, but their rate of growth slows as they mature. Most will reach sexual maturity within 7 to 10 years.
General – The shark is usually solitary, but may be found in small groups of up to 6 individuals. This species is nocturnal; it comes inshore at night to feed and retreats offshore by day but often feeds near the surface on overcast days.
Feeding – When feeding the shark uses its wide blunt snout to advantage; a tiger shark feeding on a large stingray was filmed pushing the ray’s body into the sand and between rocks — apparently to gain leverage in order to bite off a mouthful of flesh.
A tiger shark is inquisitive, and it may approach submerged divers and circle slowly at close range. Do not be lulled into a sense of security by its slow swimming movement and apparent lack of aggression; this shark may nonchalantly take a bite while remaining cool and casual. Tiger sharks have also become very aggressive toward spearfishermen and divers attracting the sharks in underwater photo sessions.
Danger to humans – the tiger shark, like its jungle namesake, is dangerous; its toll of victims throughout the world is second only to that of the white shark. It is considered the most dangerous tropical shark, and has been blamed for the majority of attacks in Australia and Hawaii. The shark’s large size, inquisitiveness and often aggressive nature, combined with large cutting teeth and indiscriminate feeding habits, dictates that a tiger shark should always be regarded as extremely dangerous.