Bull sharks are characterized by their unique width-to-length ratio that gives them a stocky and hulking appearance that differentiates them from other sharks. The coloring of the bull shark  is a form of countershading, in which the parts of the organism that are light are the ones exposed to the shadows and the parts that are dark are the ones open to the sky.

In this instance, the bull shark’s light underbelly helps the creature blend into the sky and waters lit by sunlight above, and it’s dark top side helps to camouflage it with the gloomy water beneath. 

Female bull sharks are much larger than the males, growing to 11 feet while the males stop around 7 feet. These massive critters can weigh anywhere from 200 to 500 pounds. Bull shark teeth are larger on the upper jaw and thinner on the lower.

Bull sharks can thrive in both saltwater and freshwater environments all over the world; however, they tend to reside around shallow waters that are close to the coast and are less than 100 ft. deep. Another interesting fact is that they can travel from the ocean into rivers and lakes.

Bull sharks typically feed on fish, rays, smaller mammals, and birds. They seldom feed on other species of sharks, and even more rarely due they commit cannibalism and feed on other bull sharks, but it has been known to happen, especially if one bull shark is injured within the group. 

The “bump-and-bite” hunting technique is used by the bull sharks when searching for a bite to eat. The sharks quite literally bump into their prey before proceeding to continuously bite and harass their food until the prey has no choice but to surrender.

Bull sharks reproduce via internal fertilization and give birth to young that are well, but not fully, developed. Bull sharks are unique in that instead of gestating their offspring in a placenta, the fetuses gain their nutrients through the yolk sacs that each is connected to. Each litter of bull shark offspring consists of 1-13 pups.

Bull sharks demonstrate more parental care than is probably expected- they create “nursery areas” in the mouths of large rivers to protect the pups after they are born. It’s believed that this increases chances of survival due to protection from predators as well as a larger food supply. Additionally, the bull shark is one of the few shark species that is able to explore freshwater areas, meaning that other sharks are unable to hunt the bull shark pups.

Two adaptations are essential to the survival of the bull shark in freshwater environments: the ability of the kidneys to produce a large amount of urine to prevent a build up of salts and excess water, and the ability of the liver to produce amounts of urea that are dependent on the salinity of the bull shark’s environment.

However, even with these adaptations, bull sharks can only live in freshwater environments for 4 years at a time.