SharkoFiles: Bull Shark

Bull Shark, Carcharhinus leucas, Playa del Carmen, Mexico, Caribbean Sea.

The Bull sharks are common sharks who are known for their aggressive behaviors and often live near highly populated areas such as tropical shorelines. Alongside the great whites and tiger sharks, the bull sharks are considered to be the most likely shark species to attack humans. According to the International Shark Attack File (ISAF), bull sharks have been responsible for at least 100 unprovoked attacks on humans around the world, 27 of which have been fatal. However, it is likely that this species may responsible for many more. They earn their name from their short, blunt snout and their tendency to head-butt their prey prior to launching an attack. Bull sharks can survive in both freshwater and saltwater (marine) environment, thus it is not strange to find this species of shark in rivers.

They are voracious feeders, that will eat almost anything they see. Bull sharks sometimes attack people inadvertently and out of curiosity. Due to the economic importance of the bull sharks’ body parts, they are extensively fished around the world for their meat, hides, and oils, which is causing a decline in their population. They are classified as a near threatened (NT) species.

When the bite strength of 13 different sharks and shark-like fish are compared, it was discovered that the bull shark possesses the strongest bite force of any shark. The bull sharks have been known to do well in aquariums (captivity). In the wild, the average life span of the bull shark is 16 years. Meanwhile, in captivity, a species of bull shark have been known to live up to 30 years. Generally, male bull sharks grow to about 7 feet in length, while the female grows to 11 feet.

Taxonomy

The scientific name of the bull shark is Carcharhinus leucas. The shark is one of the largest requiem sharks that is sharks belonging to the family Carcharhinidae.

Morphology

The shark species are difficult to identify due to lack of eye-catching markings or facial features. Bull sharks are distinguished from other sharks by their body’s high width-to-length ratio, which make them appear stout. Similar to several fish, the bull sharks exhibit countershading, whereby they have dark coloration of gray on the dorsal part of their body against a light coloration of white on the ventral side. Adult bull sharks often weigh between 200 and 500 pounds, with a size range between 7 to 11 feet. The bull shark’s first dorsal fin is large and triangular with a pointed apex, while the second dorsal fin is considerably smaller. They have small eyes, which suggests that vision may not be an important feature of this species that are usually found in turbid waters. The upper jaw teeth of the bull shark are broad, triangular, and heavily serrated. Lower jaw teeth have a broad base, and are narrow and triangular with fine serrations.

Adaptation

The bull shark’s countershading ability enable it to blend with the environment and makes it difficult for the prey to recognize. It is capable of fast speed, which enhance its success during hunting. It has a powerful jaw and a mouth that come handy with the type of diet of the shark being a voracious carnivore. The bull shark can regulate its body salt concentration that allows it to survive in both saltwater and freshwater environment.

Feeding

They are generally not a picky predator and will eat anything in their paths. Bull sharks are known to eat a variety of prey such as bony fishes, small sharks, some terrestrial and marine mammals, seabirds, and at times sea turtles. Bull sharks seem sluggish as they cruise along the bottom, but tend to engage in quick bursts of speed that enable them to capture smaller, more agile prey.

Habitat

Bull sharks have been found in rivers, sometimes hundreds of miles from the sea, however, their common habitat is the marine estuarine environment near to the shore. The shark prefers to live in shallow coastal water with a depth of less than 100 feet. They are so comfortable in freshwater environment that evidence suggests they can breed in such environment. Bull sharks can be considered dangerous to humans because of their tendency to find their way to an environment where humans are found, and thus often come into contact with humans, where they are responsible for fatally biting more people than any other shark species.

Reproduction

The bull sharks do not mature until they are 15 to 20 years old. They mate through internal fertilization and give birth to well-developed live young. The bull sharks do not connect to their young ones through a placenta, rather the embryos survive off of yolk sacs attached to each individual during gestation. The gestation period of bull shark is between 10 and 11 months. Bull sharks rarely come together except for mating. Newborn pups typically range between 22 and 32 inches long. Biting of the female by the male is part of mating in this species. The offspring are usually born in the summer or spring, except in warm climates where young may be born year round.

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