Bull shark - Carcharhinus leucas
WHAT TO LOOK FOR
A stocky heavy-bodied gray shark with a short bluntly-rounded snout.
Gray with a faint white band on its flank. The fin tips of young sharks are often dusky. Sometimes a bull shark’s back appears grazed, but these areas are actually bald patches caused by fluke infections that result in loss of dermal denticles from the skin.
Males mature at 5.1 to 7.4 ft [1.57 to 2.26 m], and reach at least 9.8 ft [2.9 m]. Females mature at 5.9 to 7.5 ft [1.8 to 2.3 m], and reach a length of 10.6 ft [3.24 m].
Teeth in the upper jaw are triangular and strongly serrated, those of the lower jaw are slender, pointed and edged with fine serrations.
Usually found close inshore in water less than 100 ft [30m] deep.
Tropical and subtropical shallow coastal waters worldwide. This species has the ability to penetrate fresh water; it has been caught 2,294 miles [3,691 km] up the Amazon River in Peru, 340 miles [547 km] up the Zambesi River, and Lake Nicaragua has a landlocked population.
Prey – The shark feeds primarily on bony fishes, but it is a versatile and opportunistic feeder and will eat smaller sharks, skates, turtles, birds, mammals, crustaceans and offal and garbage. The shark uses the teeth of its lower jaw to impale prey, then it swings its head from side-to-side using the heavy triangular teeth of its upper jaw to carve a mouthful of tissue from its prey.
Reproduction – Viviparous, with yolk-sac placenta. Litter size ranges from 1 to 13. Size at birth is 22 to 31 inches [56 to 81 cm]. Gestation lasts nearly a year.
General – divers report that the sharks are rarely seen at the surface; most are observed cruising over the top of the reef, and are frequently hosts to remoras.
This is a large, aggressive shark with massive jaws and it moves like a seasoned warrior. The GSAF has several cases in which the rapid ascent of a diver may have ‘released’ an aggressive response (similar to when an intruder flees from a guard dog). In each case, after a single bite on the diver’s leg (no tissue was removed by the shark), the shark sped back to the reef. More often, when this shark bites, it resembles a pit bull; it makes multiple bites accompanied by head-shaking to remove tissue, and inflicts injuries that are far more difficult to repair than those caused by a white shark. Perhaps because the shark scavenges on carrion and may make forays into polluted areas, wounds caused by this species have a higher-than-usual rate of infection.
Danger to humans – due to its size, dentition and aggressiveness, it is regarded as one of the most dangerous tropical sharks.