Creature Feature: Bull Sharks

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  • By Melissa Johnson
  • Posted in Events
Creature Feature: Bull Sharks

During our dive, we often see marine animals like fish, eels, lobster and rays. We may even encounter dolphins swimming alongside the boat, or Goliath Grouper gathered around a wreck. Occasionally, we spot a seahorse or an octopus nestled under the Blue Heron Bridge, one of our favorite shore diving spots. Sometimes, however, divers meet an animal even more rare (and much larger) as they drift over the reef. If you have observed a bull shark cruising along in the sea, consider yourself lucky!

As “apex predators,” bull sharks are an important indicator that our reef system is healthy. Unlike many shark species, bull sharks aren’t limited to their saltwater surroundings.

 

Bull sharks are unique, in that their bodies undergo osmoregulation. Osmoregulation facilitates the retention and regulation of the amount of salt in their systems. This allows them to transition comfortably between saltwater and freshwater habitats.

 

Image courtesy of Force-E Photo Pro Nikole Heath.

 

Perhaps surprisingly, bull sharks have been found in freshwater rivers as far inland as a few thousand miles. In fact, one bull shark was recorded swimming in the Mississippi River as far north as Illinois!

 

Female bull sharks, in particular, take advantage of this unique ability. They birth pups in brackish estuarine habitats. Females give birth to up to 13 pups at a time. Baby bull sharks are born free swimming.

 

Bull sharks have a number of other distinct attributes.  Most sharks have a sleek, stream-lined appearance. Many divers, however, describe bull sharks as “stocky” in appearance. They feature a broad, triangular dorsal fin, with a smaller second dorsal farther along their backs.

 

Image courtesy of Matt Heath.
 
 Typically, female bull sharks are larger than their male counterparts. The largest bull shark on record weighed in at around 500 lbs. It measured over 11 feet in length.

 

Bull sharks have a broad, short snout. This is a key feature that led to their name. When hunting, bull sharks ram into, or “head-butt,” their prey to stun it.

 

They have relatively small eyes. Their propensity for spending time in brackish estuaries and murky river water means that they do not rely heavily on their sight. Bull sharks are also inherently curious animals, and opportunistic, indiscriminate feeders. Coupled with their poor vision, these factors often contribute to their label as an aggressive shark species.

 

Bull sharks have a very strong bite, when compared pound-to-pound with those of other sharks. This helps them chomp through thick shells. They are some of the least picky eaters of the marine world. Bull sharks will munch on fish, birds, marine mammals, and even other sharks.

 

Unfortunately, bull sharks’ home of coastal regions puts this important species at risk. Habitat loss due to coastal development directly impacts bull sharks and their pups. They are also more likely to be effected by chemicals and pollutants often found in freshwater runoff.

 

To learn more about sharks, follow us on Facebook! Check out all of our “shark facts” posted throughout the month of September.

 

If you love sharks as much as we do, book a dive with us to see them in person! We can arrange charters going to some of our local sharks’ favorite hangouts.

 

We hope you have a “jawsome” week!