The Bull Shark – They’re everywhere you wouldn’t expect them to be! Known as the Carcharhinus Leucas in the scientific community, it has a stocky figure and a broad, flat snout. This is one of 43 shark species that can live in both seawater and freshwater. That fact alone makes this one of the best known shark species. This species is known by several different names depending on its whereabouts: Zambezi Shark, Nicaragua Shark, or Ganges River Shark.
But this shark is also known as one of the top 3 sharks most likely to attack humans (the other 2 are the Great White Shark and the Tiger Shark). Of course, we know that shark attacks are extremely rare (less than 4.5 deaths by shark attacks per year globally), but nonetheless, this shark has been nicknamed “The Pit Bull of the Sea” because if its aggressive behavior.
Most sharks have the same salt concentration in the blood as the sea water they are swimming in. This isn’t the case with Bull Sharks. Instead, they only have 50% of the salt concentration in their blood. This makes them very special as they are able to switch from saltwater to freshwater very easily. The only consequence is they produce 20 times more urine when swimming in fresh water.
After about 10 years, they reach maturity. Adults are normally about 3.5 meters (11 feet) long and weigh approximately 300 kilograms (660 pounds). Typically, females are larger than makes and generally live longer. Most males live for about 13 years, while females live to about 17 years of age.
These special hunters are migrants. They are found in many various areas including Oceans, rivers, and even some fresh water lakes! They tend to stay in warm and moderately deep waters around 30 to 150 meters (150 to 500ft) deep.
It seems the Bull Shark favors the Atlantic, Indian, and Pacific Oceans. Some of their favorite rivers include the Brisbane River, Amazon River, Ganges River, Barhamputra River, Potomac River and the Mississippi River. They have been spotted several hundred miles upstream in these rivers, but typically stay within 100 miles of the Ocean. No attacks on humans have ever been recorded in these rivers.
They are in fresh water lakes, too! It’s not too uncommon to see them in Lake Nicaragua and Lake Ponchartrain, just to name a couple. But if there is easy access from a river and the lake is deep enough (about 30 meters or 150 feet), they’ll check it out and maybe even make themselves at home for a while.
This is one of the more social species and sometimes even hunt in groups. There is still quite a bit of mystery surrounding their social structure, but it seems females tend to have dominance over males.
The Bull Shark is known to eat almost anything. The preferred prey includes bony fish, small sharks, turtles, birds, and some species of dolphins.
These sharks are Viviparous, which means pup sharks develop in the womb of its mother, similar to humans. Typically, the pregnancy period is about 1 year, usually during the summer months but sometimes in early autumn as well. Pups are about 60cm (24in) and mothers give birth to 5 to 15 pups at once.
Interactions with Humans
While the Bull Shark is one of just 3 shark species to attack humans unprovoked, attacks are extremely rare. Especially when you consider that thousands of people wash their bodies daily in the Ganges River for religious purposes. This just so happens to be a preferred area for the shark.
This species is not hunted much by humans. The biggest human threat to these creatures are getting caught in fish nets.