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The Extraordinary Bull Shark
Some sharks are named for their appearance like the blue shark, the hammerhead shark and the blacktip shark. Others are named for where they are found, like the Galapagos shark, the Japanese wobbegong and the Greenland shark. Then there are sharks that have the same name as fierce land animals like weasel sharks, houndsharks, the tiger shark and the infamous bull shark.
1. Well Named
Why is it called the bull shark? There are three reasons.
One, the bull shark is heavily built with a stout, rounded body and a large, blunt snout.
Two, the bull shark has a bad temper. In fact, it is known for being one of the most aggressive sharks. It is territorial so if you mistakenly step into its territory, you’re dead meat. It also doesn’t like bright colors and tend to attack brightly colored nets more than lightly colored ones.
Three – what happens when the bull shark has a bad temper? It bites. But before it bites, it bumps using its snout, just like bulls attack headfirst. So when a bull shark bumps into you, beware. It’s no accident and unless you like to lose a chunk, it’s best to get out of the water while you can.
The scientific name of the bull shark is Carcharhinus leucas. Carcharhinus comes from the Greek words karcharon and rhinos, which, together mean ‘sharp-nosed’, referring to the bull shark’s large nose. Leucas is Greek for ‘white’. However, the bull shark isn’t white. It’s gray on top and white on the underside, which allows it to blend into the water. Some juveniles have black-tipped fins.
The bull shark is also known as the Zambezi shark, the Nicaragua shark, the Ganges shark, the river shark, the ground shark, the shovelnose shark and the square-nosed shark.
2. A Good-Sized Catch
The bull shark can grow over 7 feet long. In fact, females average 7.8 feet long and weigh 285 pounds. The males are smaller, growing up to around 7.3 feet long and weighing about 209 pounds. Females are larger because they carry pups. They grow more slowly, though, and live longer – up to 16 years.
Some say, however, that bull sharks can grow over 10 feet and there are reports of bull sharks reaching up to 13 feet long. There are also reports of bull sharks weighing around 1,000 pounds.
3. Some Like It Fresh
Bull sharks are one of the few sharks that can live in both saltwater and freshwater. In fact, they are commonly seen in freshwater habitats, such as rivers, lakes and streams all over the world. Bull sharks can switch from saltwater to freshwater and vice versa because they have only half the concentration of salt in their blood than that of the water around them, whereas most sharks have the same concentration of salt in their blood as there is in the water around them.
In order to maintain this concentration, bull sharks have a special gland called the rectal gland. In saltwater, this gland serves to get rid of excess salt. In freshwater, it conserves salt. The kidneys of the bull shark also adjust. In saltwater, the kidneys get rid of excess salt. In freshwater, the bull shark produces more urine. However, the urine contains mostly urea and less salt. Urea is a nitrogen-rich compound that sharks store in their blood in order to prevent dehydration when in saltwater. In freshwater, however, the bull shark doesn’t have to worry about becoming dehydrated. It can simply absorb water through its gills and so it gets rid of the urea. Also, the bull shark’s liver produces less urea in freshwater.
Amazingly, a bull shark’s kidneys and liver adjust depending on how salty their environment is. The older the bull shark gets, the more tolerant it becomes of saltwater and so adult bull sharks are often found in the ocean.
4. Lurking In Shallow Waters
Did you know that adult bull sharks can survive even if the water is just two feet deep? That’s right. Bull sharks can live in shallow water. In fact, many of them prefer it, which is why they often come in contact with humans. Many female bull sharks also give birth in shallow waters, which prevents their young from getting eaten by the bigger sharks that lurk in deeper waters.
5. A Large Appetite
Like other sharks, bull sharks are efficient hunters which hunt using their keen sense of smell and their sixth sense – detecting electric fields using their ampullae of Lorenzini. They are solitary hunters and can hunt both day and night.
What do they hunt? A bull shark’s diet consists mostly of fishes, including other sharks and stingrays. They also eat dolphins, turtles, starfish, sea urchins, crustaceans, birds and even land mammals that come to drink at the water’s edge such as dogs and pigs. Bull sharks, like all sharks, are opportunistic feeders, which means they will eat anything they can sink their sharp teeth into.
6. Watch Out For That Puke
As fierce as they are, bull sharks are not at the top of the food chain. In the ocean, they can be preyed on by larger sharks, including larger bull sharks, as well as killer whales. In rivers, they can be preyed on by crocodiles. In order to get away, bull sharks employ a special technique – they throw up! The predator gets distracted by the vomit and the bull shark gets a chance to escape. As disgusting as it is, it works. Even some vultures do it, too.
7. Bite That
Guess who has the strongest bite force of all sharks? If you said the great white shark, sorry but you’re wrong. The great white shark may be the largest predatory shark out there and it may be really strong and dangerous but scientists have discovered that bull sharks have the strongest bite, its jaws able to exert a maximum force of 6,000 Newtons. That’s enough force to lift something that weighs about 1,300 pounds like three full grown lions. With such force, you can imagine how much damage a single bite from a bull shark can do.
8. Pups Out
Bull sharks are viviparous, which means they give birth to live young just like mammals do. The female carries her babies called pups – she can have up to 13 of them – for 10 to 11 months, then gives birth. As soon as they are born, the mother swims away, leaving the pups to survive on their own, which they are capable of since they are already over two feet long at birth.
9. Third Deadliest
Because of their preference for freshwater and shallow waters as well as their aggressive temper, bull sharks are considered the third deadliest sharks in the world. They are responsible for 100 confirmed unprovoked attacks on humans, 21 of which were deadly. Bull sharks are also believed to be the ones behind the infamous Jersey Shore attacks of 1916, during which four people were killed in the span of 13 days. These attacks served as the inspiration for the popular movie ‘Jaws’.
Still, the chances of being attacked by a bull shark are less than those of drowning or even getting hit by lightning. And there are things you can do to avoid it such as not swimming near schools of fish, near river mouths and in murky waters where bull sharks like to lurk.
10. Near Threatened
Bull sharks are not endangered as many species of sharks are. However, they are still hunted for their fins, skin, meat and liver oil. They are also caught for sport and for public display in aquariums, since they are one species of shark that can do well in captivity. The pollution and destruction of rivers and lakes can also have a negative effect on their population.