A Bull Shark is strong, fast, aggressive, and adaptable; of the three most dangerous sharks – Great White, Tiger, and Bull – it is perhaps the one we know least about. We love to spend time at warm beaches, wading or swimming close to shore; we enjoy a dip in lakes in rivers on hot summer days. These are the same places where the Bull Shark lives, grows, hunts, and gives birth. These powerful predators call our summer retreats their home, and are closer to your own home than you may realize. We love the same places, why not learn more about them? Take a look!
Their Secret Weapon: They Can Live In Salt or Fresh Water
You may have heard the fact that makes the Bull Shark exceptional among its peers: it can adapt to live in salt water, brackish, and fresh. This truly is an astounding advantage and comes as a surprise to many people.
The Bull Shark can, in theory, survive indefinitely in fresh water. In fact, they are born in fresh water; they are, however, not a fresh water shark and have not been known to live in fresh water conditions permanently.
Instead, they tend to spend much of their lives in shallow, warm waters, preferring 3-100 ft and ranging out to 450 ft. There, in the summer months, they mate, returning to the fresh water to give birth after a 10-11 month gestation.
An exception that we know of at this time is the Breede River of South Africa. Here, while accompanying a team of scientists, Jeremy Wade caught a 500 pound male bull shark. The find confirmed that large males will enter the river, almost certainly in order to feed. Bull sharks here seem to follow boats in order to scavenge from fishermen, and one shark actually stalked the boat Wade was working from. Interestingly, though bull sharks feed in the river, there was no record of any attacks on humans there. If you are interested, this was season 2, episode 6, “Hidden Predator.”
Wade went to this river in part because scientists here had landed the largest bull shark on record: a 1000 pound, 13 foot female.
Did You Know?
- In 1937 a 5 ft Bull Shark was caught in the Mississippi River in Alton Illinois, meaning it swam 1750 miles from the Gulf of Mexico to get there.
- Once thought to be a separate species, it was realized that the Nicaragua Shark was in fact the same species. Bull Sharks had been swimming 2,500 miles up the Amazon River to get there.
- Consider: Between the two of these, that is 4,250 miles of river, and this is only a fraction. The Bull Shark can be found in rivers and lakes around the world and has been consistently seen in Indian (in the Ganges), South African (where they are referred to as Zambezi Sharks), and Australian river systems.
Despite this astounding ability to adapt, Bull Sharks spend most of their lives in brackish and salt water where their main known food sources can be found,
At sea they will eat:
- Bony Fish
- Smaller Sharks
- Turtles
- Stingrays
- Marine Mammals
However, as opportunistic feeders, if their known food sources dwindle they will seek out alternatives, possibly being driven into fresh water in search of new prey.
So, naturally you may wonder:
Do Bull Sharks Eat Humans?
You may be wondering if Bull Sharks will eat humans. Why not?
They spend most of their time in warm shallow water, the same water humans like.
They swim up freshwater rivers, the same ones where humans wade often without considering a hungry 300 lb carnivore may be right beside them
In practice, this close proximity serves to show the opposite is true: with Bull Sharks and humans so close, it would be very clear to us if they considered humans as a food source. Thankfully they are not known to actively hunt humans.
OK, they don’t hunt humans; not a threat then?
Be careful with this one: not actively hunting us does not mean that they are safe to be around, and it does not mean they will never see you as food. They have been known to attack cows and hippos, if they are hungry enough they will taste you as well. This is not to spread fear but awareness: they are not hunting you, and rarely are humans ever attacked, but these are wild animals; there is no rule stopping them and when food is scarce these highly adaptable creatures will experiment with new sources.
The Most Dangerous Shark?
Although, like other sharks, the Bull Shark will most likely injure or kill a human ‘by mistake’, the intention is little comfort to those at the receiving end, and the Bull Shark has a few traits that make it perhaps the most dangerous of all sharks to be around.
The Bull Shark is:
- Highly territorial
- An opportunistic feeder
- Very aggressive
In fact, their aggressiveness helped earn them their name, reminding observers of an angry bull. The similarity does not end there either, they head-butt their prey like a bull before going in for their kill.
their aggressiveness helped earn them their name, reminding observers of an angry bull
Their High testosterone makes them so aggressive. Or does it?
Although you will hear that Bull Sharks have the highest testosterone of any animal, this is not a well-backed claim and could even be called a myth. The highest number came from a study which only tested 3 sharks, and only tested each shark once. Although one male had a level of 358 nanograms per mililiter, another had just 2.7 while a female had only 0.1. The one male was high but so far as we know he was a freak of nature.
The other male had 2.7 ng/mL. Let’s compare that to the average human male, who has a range of 2.5-9.5 ng/mL. This second male Bull Shark has low testosterone even for a human! The two other studies were equally inconclusive.
With a total of 121 recorded attacks, including 25 unprovoked fatal attacks, Bull Sharks are among the top three dangerous sharks to humans, numbers one and two being the Great White and Tiger Shark respectively. Scientists speculate some of these attacks previously attributed to other species may have actually been Bull Sharks as well.
Are Bull sharks Aggressive? Yes. Are Bull Sharks Dangerous? Yes. Are Bull Sharks testosterone driven indiscriminate killing machines with a thirst for human blood? No. They are a powerful and unique wild animal to be respected and feared, but within reason and with consideration to their place in the ecosystem and respect to the environment with which these organism perform the ultimate dance as they play out their cycle of life. In conclusion, they are incredible creatures best enjoyed from a distance.
Normal adult bull shark size ranges from 7 feet (2.1 meters) length for males with the females even larger at 11 feet (3.3 meters). They weigh 200-500 pounds (91-227 kg).
Myth: The movie “Jaws” was inspired by a series of shark attacks in New Jersey, 1916, thought to be by a Bull Shark.
Fact: “Jaws” was based on a book of the same name by Peter Benchley. He says the book was not inspired by the 1916 attacks, but by a combination of childhood shark hunting experiences and an especially impactful story of a 4500 pound Great White shark captured near Long Island in 1964.