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Bull sharks, Carcharhinus leucas, are inherently smart,

independent sea creatures. These mammals fall under the

class of Chondrichthyes which give them their large jawed

vertebrates and skeletons made of cartilage rather than bone.

The bull shark is viviparous, and they age to reach sexual

maturity depends on the geographic region but usually the age

is 10 years old for males and 11 years old for females. Since

bull sharks like to stay close to shore in shallow waters, they

are known for the most registered human attacks (Edmonds &

Kiger, 2008). These sharks enjoy waters ranging from South

Africa to Kenya and from India and Vietnam to Australia.

These creatures will feed off of anything that comes their

way…especially in freshwater. The Bull sharks most

interesting feature is that it they can tolerate freshwater for

long periods of time.

ABSTRACT

HABITAT

Bull sharks are capable of living in saltwater and

freshwater environments, this is possible because of a process

called osmoregulation. Osmoregulation is the ability to

maintain an constant concentration in its body. If you compare

a tiger shark and a bull sharks blood, you will find that the

bull shark has about 50% less of the salt concentration of the

blood of a tiger shark. When bull sharks are swimming in

saltwater they are consistently drinking salts while their

kidneys are simultaneously excreting them through their

rectal glands with small amounts of urine. When these sharks

are in fresh water they take in more water through their cells

and decreases the amount of salts in the the large amounts of

urine they excrete. Many organs rely on salts to continue

functioning, without them they would die. With the help of

special glands near their tails, bull sharks, are able to store

excess salts for when they need them (Reilly 2011).

FRESHWATERINTOLERANCEBull sharks eat almost anything that comes along its

path, from boney fish and sea turtles to other small sharks

and from shrimp to stingrays and birds. These sharks are

known to be one of the deadliest in the world considering they

have no fear towards humans, yet attacks are still extremely

rare. Due to inhabiting murky waters, their sense of smell is

heighten and the use of their long nose comes in handy; the

bump-bite technique is most commonly used. When they find

their prey, they swim directly towards it reaching speeds of

about 11mph (Curtis 2018).

FEEDINGHABITS

REPRODUCTION

A bull sharks reproductive cycle begins at the end of the

summer months in shallow and low salinity river mouths.

Since bull sharks are viviparous, the female bull shark carries

her pups (usually anywhere from 2-10) for approximately 10-

12 months. Once the pups are born they naturally free

themselves from their mother, which is the reason for the high

mortality rate, where they find ‘nursery’ habitats which

consist of shallow river mouths, coastal lagoons, and brackish

water estuaries. Since the pups can immediately swim away,

they are normally born in a flat-bottomed fresh water river

because of the amount of security. Although we don't know

much about the mating behavior of bull sharks we do know

that the female needs to reach two meters in length before she

is ready to produce eggs for successful fertilization. Males

reach their sexual maturity around 14 years. When beginning

to mate, the male approaches the female, bites her tail leaving

significant scratches, and then continues to do so until the

female flips over insinuating she is ready to reproduce

(Cascio 2017).

REFRENCES

Bull sharks have a wide range of places they resort to

but they mostly enjoy tropical and warm waters worldwide,

with temperatures ranging from 69 to 86 degrees Fahrenheit.

They inhabit coastal areas, such as the coast of The Gulf of

Mexico, eastern coast of North and South America, and the

western coast of Africa (Curtis 2018). Bull sharks stay within

depths of 150m, but typically stay at depths less than 30m.

With bull sharks having the unique capability to move freely

throughout salt water and fresh water, they are often found

long distances up rivers around the world. The Amazon,

Mississippi, and Ganges river are just a handful of freshwater

areas that have been know to house these sharks.

San Diego Miramar CollegeBy: Brittany Buckley

Bull Sharks

Bull shark in the Bahamas. Photo © David Snyder

Bull Shark distribution at a global level. Map © ChondrichthyanTree of Life

Saltwater osmosis ©2016 Joshua k. Moyer and William E. Bemis

Freshwater osmosis ©2016 Joshua k. Moyer and William E. Bemis

Bull shark eating tuna head. © Sascha Janson www.uw-pix.com

Bull Shark Reproduction. (n.d.). Retrieved fromhttp://www.private-scuba.com/sea-life/marine/vertebrates/sharks/bull-sharkreproduction.html.

Cascio, K. (2017). Carcharhinus Leucas Club Shark. Retrieved from https://animaldiversity.org/accounts/Carcharhinus_leucas/#reproduction.

Curtis, T. (2018, October 18). Carcharhinus leucas. Retrieved from https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-leucas/.

Edmonds, M., & Kiger, P. J. (2008, June 05). The 10 Most Dangerous Sharks. Retrieved from https://animals.howstuffworks.com/fish/sharks/most-dangerous-shark9.html.

Heupel R. M., Simpfendorfer A. C. (2008, February 5). Movement and distribution of young bull sharks Carcharhinus leucas in a variable estuarine environment. Retrieved from https://www.int-res.com/articles/ab2007/ 1/b001p277.pdf.

Lee, Y. L., Lemckert, J. C., Otway, M. N., & Werry M. J. (2012,November 16). Retrieved from https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0049796.

Reilly D. B., Cramp L. R., Wilson M. J., Campbell A. H., Franklin E. C. (2011). Retrieved from http://jeb.biologists.org/content/214/17/2883.

Simpfendorfer, C. & Burgess, G.H. (2009). Carcharhinus leucas. Retrieved from https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-leucas/.

Snelson, F. F., Mulligan, T. J., & Williams, S. E. (1984, January 1). Food Habits, Occurrence, and Population Structure of the Bull Shark, Carcharhinus Leucas, in Florida Coastal Lagoons Retrieved fromhttps://www.ingentaconnect.com/content/umrsmas/bullmar/1984/00000034/00000001/art00004#.

Carcharhinus leucas