Bull Sharks : Unusual habitat adaptation


Bull sharks are quite common. These type of sharks  live near the tropics, they love the heat and are quite adventurous. Brackish waters do not deter them. They can venture inland through the rivers and its tributaries. So beware as it can live near densely-populated shorelines along the tropics. It can thrive both in saltwater and freshwater.  While most sharks can only live in saltwater, this species have edged higher in the evolution by adapting through keeping salt in their body  even they are in freshwater. Their kidneys and special glands at the tail end serve as the “salt reservoir” and marine experts are still conducting researches when or how the bull sharks have developed this extraordinary ability. Another interesting tidbit: bull sharks especially the female one go to freshwater when they’re pregnant and ready to give birth.

Why did they give birth in freshwater when they can tolerate high salinity in saltwater? one of the major reasons is the protection freshwater gives. According to marine scientists, the young bull sharks can fully develop and mature in freshwater as their is lesser threats of larger sharks and alos big fishing vessels unlike in the wide open sea.

Bull sharks also give birth live while other sharks lay eggs. The female bull shark is pregnant for 10 to 11 months.  It starts to mate and reproduce starting at the age of 15 (for male bull sharks) while females wait until it turns 18 years.

Since bull sharks have developed an ability to stay longer in freshwater, its population increased as its survival rate is quite high.

Some marine explorers and photographers of National Geographic considered the bull sharks as one of the most deadly attackers. Alongside the great  white tiger shark (the legendary hunter) , the bulls sharks can smell blood. Its usual diet is the fish. It also eats dolphins and other smaller sharks. Historically, humans are not part of its usual prey but since it will eat anything and the fish catch are dwindling, then reports of human attacks have increased.


They found in areas with warm oceans, estuaries, rivers and lakes and can stay in water with a depth of 150 to 30 meters.

It ha sbeen found in major rivers of Brisbane and Queensland,  Australia. A good numbe ris also sighted in Amazon River and Iquitos in Peru, Lake Nicaragua and Ganges River in India. It is also found in South Africa in the St. Lucia Estuary , which is considered with the highest salt content in its water.

After several disaster like Hurricane Katrina, there were also several sightings of bull sharks in Mississippi River,  Potomac River.  In fact, several bull sharks trapped during the 1990 flooding in Queensland in one gold course served as a local attraction.

,The bull sharks (Carcharhinus leucas) got its name from its blunt snout and its capacity to kill through its butting its head onto its prey. They are usually medium-sized, colors grey and body is white with dark fins. The young bull sharks usually are the most curious ones. As humans are not on their usual menu, these young ones are reported to attack people and marin experts think this is out of curiosity and/or  in self-defense.

Deadly attacker and ferocious hunter, the bull sharks hunt during the day and night.


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