Bull Sharks - San Diego Miramar Collegefaculty.sdmiramar.edu/faculty/sdccd/alowe... · 2018. 12....
Transcript of Bull Sharks - San Diego Miramar Collegefaculty.sdmiramar.edu/faculty/sdccd/alowe... · 2018. 12....
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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