Bull Shark (Carcharhinus leucas)

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Bull Shark Carcharhinus leucas

The bull shark, also known as the Zambezi shark in Africa, gets it's name from it's stocky build, it's broad snout, it's aggressive nature, and a tendency to head-butt it's prey before attacking. Bull sharks are arguably the most dangerous shark of all. They are among the top 3 most dangerous sharks in the world, alongside the tiger shark and the great white. Because the bull shark is very common, and lives in coastal shallow waters, often murky waters, they are considered responsible for most of the shark attacks that take place near the shore, even when the actual type of shark is not clearly identified. Due to it's agressive nature this shark has been nicknamed "The Pit Bull of the Sea."

Description

The bull shark's body is compact with a snout that is short and broad which gives it a somewhat blunt appearance. Bull sharks are short, wide and heavy fish, with a very powerful bite. The bull shark is grey with a white belly. They are a chunky species and the dorsal fin is relatively far forward on the shark's back. They have small beady eyes, making scientists believe that their eyesight is poor, hence their ability to thrive in the murky water that is commonly found in rivermouths and rivers. An adult bull shark's teeth are triangular, serrated, very sharp, and approximately 1.5" long.

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Bull sharks grow at about 11 inches a year for their first four years, and then at about six inches a year until fully mature. Females tend to be larger than males, mostly due to their longer lives; females live to be about 16 years old and reach maturity at about 10 years old and seven feet long, males live to about 12 years old, and reach maturity at 9 years and six feet long. The largest bull shark on record was 13 feet long and weighed close to 1000 pounds.

Range and Habitat

Bull sharks are commonly found worldwide in warm, shallow waters along coasts and in rivers, they prefer warmer equatorial, tropical and subtropical waters. Bull sharks are one of the very few sharks that have the ability to live in both salt and freshwater. They can be found in fresh water that connects with salt water (rivers and lakes) and have been caught in the Mississippi River as far upstream as Illinois.

Off the Atlantic coast of the United States, bull sharks are found from Massachusetts to the Gulf of Mexico and are common off southeastern Florida and in the Gulf of Mexico. Off the Pacific coast, bull sharks are found from southern California (rare) to the Gulf of California.

Here is an interactive map depicting the worldwide range of the bull shark.

Diet

Bull sharks are typically solitary hunters, they are very territorial and can be highly aggressive. They are known to make sharp turns, unpredictable bursts of speed (up to 11 mph) and often utilizes the "bump and bite" technique to capture prey, during which it first head-butts prey before attacking. Bull sharks are not picky eaters, they are opportunists and will eat almost anything they see: bony fish, turtles, birds, mollusks, crustaceans, dolphins, other sharks, and rays. They have also been known to eat birds, sloths, dogs, rats, cows and antelope! Like other sharks, they're able to find their prey with their keen sense of smell.

A bull shark cruising the shallow waters of the Carribean.
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Human-Shark Encounters

"Bull sharks inhabit quite shallow waters, which means that they do have a great opportunity to interact with humans, because the two species tend to share the same areas," said George Burgess, curator of the International Shark Attack File at the Florida Museum of Natural History in Gainesville.

According to the International Shark Attack Files, there have been 104 recorded bull shark attacks in the last 150 years, and out of those, 33 fatalities. While this number is probably under-reported due to the wide habitat of the bull shark which includes many third-world countries which do not report attacks, it is still an incredibly low number when you consider the number of people that enter the ocean every year.

Humans are a far greater threat to the shark population than they are to us. We fish them for sport as well as commercially, and their fins are also prized in Asian markets to turn into shark's fin soup.

Tiger Shark (Galeocerdo cuvier)

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Tiger Shark Galeocerdo cuvier

Tiger sharks are one of the top three sharks implicated in unprovoked, fatal attacks throughout the world. Although shark attacks are a relatively rare phenomenon, the tiger shark is responsible for a large percentage of fatal attacks and is regarded as one of the most dangerous shark species.

Description
The tiger shark has many distinctive characteristics making it easy to distinguish from other sharks. The tiger shark is named for the dark black spots and vertical tiger-stripe markings that are very prominent in juveniles but that often fade as they mature. It has a short, blunt snout, and a big mouth with large, saw-edged, cockscomb-shaped teeth.

This is one of the larger shark species; tiger sharks usually range from between 3 to 5 metres in length. Although much larger specimens have been seen, the largest a tiger shark tends to get is around 5.5 metres long.

Range and Habitat
The tiger shark is found in warmer and tropical waters in the Southern Hemisphere. The tiger shark tends to be found in more coastal waters but tigers sharks are also known to go into the deeper ocean if they need to hunt for food. They seem to prefer turbid coastal areas where fresh water runoff occurs as different prey species may congregate to feed in these areas. They are commonly found in river estuaries and harbors.

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In North America, they are found on the East coast from Massachusetts down to the Gulf of Mexico and the Caribbean. On the West coast, they are found in Southern California and in Hawaii. They are also known to seasonally migrate, moving from temperate to tropical waters in the winter; they also make long migrations between islands in the Pacific. Other locations where tiger sharks are seen include Africa, People's Republic of China, Hong Kong, India, Australia and New Zealand.

Diet
These solitary hunters are nocturnal and move inshore into shallow waters at night to feed and then move back to deeper waters in the daytime. Their diets include bony fishes, sharks, rays, porpoises, turtles, crabs, squid, birds, and even garbage. They are not picky eaters.

Shark-Human Encounters
While the tiger shark is considered to be one of the sharks most dangerous to humans, the attack rate is low considering the thousands of people who swim, surf and dive in the ocean every day. The tiger shark is second only to the great white shark in number of reported attacks on humans. Tiger sharks often visit shallow reefs, harbors and canals, greatly increasing the potential for encounter with humans. It’s not known why tiger sharks sometimes bite humans. The idea that they mistake a person for a natural prey item, such as a turtle, is not supported by any evidence. The shark may be trying to determine if a person is a potential prey item, it may come across a person while in a feeding “mode,” or perhaps there is some other explanation. According to the International Shark Attack File (ISAF), there were only 75 confirmed cases of unprovoked shark attacks on humans world wide in 2011.