Carcharhinus leucasCub shark(Also: Ground shark; Shark)

Geographic Range

The Bull Shark inhabits coastal waters in tropical and subtropical seas worldwide. (Enchanted Learning 2000)

Habitat

Although Bull Sharks have been caught in considerably deeper water, they most often reside in water between 30 meters and waist deep. The sharks also seem to favor murky water for hunting. It is one of the only sharks that is able to survive in freshwater for extended periods of time. (Australian Museum 1999, Smith 1999)

  • Aquatic Biomes
  • reef
  • lakes and ponds
  • rivers and streams
  • coastal

Physical Description

The Bull Shark can be recognized by its unique body shape, which is much wider in comparison to its length than other sharks, and its snout, which is wider than it is long. These features give the Bull Shark an almost stout appearance. The shark is gray on the top half of its body and off white underneath. Several individuals have been found with pale stripes on the sides of their bodies. The Bull Shark also has two dorsal fins, the second of which is much smaller than the first. Males of the species are approximately 7 feet long and weich 90 kg while females grow to 11.4 feet on average and weigh 230 kg. The young sharks can be distinguished by the dark edges on their fins. (Australian Museum 1999, Enchanted Learning 2000)

  • Sexual Dimorphism
  • female larger
  • Range mass
    90 to 230 kg
    198.24 to 506.61 lb

Reproduction

Bull Sharks are viviparous, meaning they give birth to live young that are nourished inside the mother shark. Sexual maturity is reached between the ages of 8 - 10. Bull Sharks breed in the summer months and the young sharks are born approximately one year later. The pups are born in litters of up to 13 and are around 28 inches at birth. A common breeding place for the Bull Shark is the brackish water where freshwater rivers meet the saltwater oceans. (Microsoft Encarta 1997, Enchanted Learning 2000)

  • Average age at sexual or reproductive maturity (female)
    Sex: female
    6570 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    6296 days
    AnAge

Lifespan/Longevity

Behavior

The Bull Shark is a solitary species that hunts by itself. Most individuals are not migratory, however many Bull Sharks in South America have been known to migrate thousands of miles from the Amazon River to the Atlantic Ocean. The largest threat to the shark is the large number of humans who fish for it commercially. It also is preyed upon by other large sharks especially in its juvenile stage. One interesting behavior is the Bull Shark's willingness to enter freshwater areas. The shark has been found far up the Mississippi and Amazon Rivers and also in Lake Nicaragua. Scientists thought the sharks in Lake Nicaragua were a separate species until they discovered that Bull Sharks were jumping the rapids, much like salmon, to enter the lake. (Enchanted Learning 1999, Bilson and Bilson 1999)

Food Habits

The Bull Shark is an omnivorous animal. It routinely preys upon fish, sharks (especially young sandbar sharks), rays, turtles, echinoderms, birds, mollusks, dolphins, and almost anything else it can find. Remains of everything from humans to hippopotami have been found in Bull Sharks' stomachs. (Australian Museum 1999, Bilson and Bilson 1999)

Economic Importance for Humans: Positive

The Bull Shark is one of the most commonly caught sharks in the world. It is frequently used as food in coastal areas and its skin is used to make leather. (Smith 1999)

Economic Importance for Humans: Negative

Bull Sharks have an appetite for young Sandbar Sharks. Because many Sandbar Sharks do not reach maturity, this has a negative impact on the large commercial businesses that fish for them. (Smith 1999)

Conservation Status

Other Comments

The Bull Shark is considered by many people to be the most dangerous shark alive. Its close proximity to populated shoreline areas and its aggressive behavior makes it extremely dangerous to humans. Despite the notoriety of other sharks such as the Great White and the Tiger Shark, the fact that they live in deeper ocean waters makes them less dangerous. (Australian Museum 1999)

Contributors

Rick Crist (author), West Windsor-Plainsboro High School, Joan Rasmussen (editor), West Windsor-Plainsboro High School.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

References

1997. "Sharks". Microsoft Encarta Encyclopedia. The Microsoft Corporation.

Australian Museum, 1999. "Bull Shark, Charcharhinus leucus" (On-line). Accessed 4/11/01 at http://www.austmus.gov.au/fishes/fishfacts/fish/cleucas.htm.

Bilson, S., M. Bilson. 2000. ""Dangerous Sharks"" (On-line). Accessed 8/3/00 at http://www.ozemail.com.au/~bilsons/Sharks2.htm.

Enchanted Learning, 2000. "Zoom Sharks" (On-line). Accessed 8/3/00 at http://www.enchantedlearning.com/subjects/sharks/species/Bullshark.shtml.

Smith, W. 1999. ""Bull Sharks"" (On-line). Accessed 8/3/00 at http://www.caske2000.org/sharkbull.htm.