Habitat
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- Sharks have adapted to living in a wide range of aquatic habitats at various temperatures. While some species inhabit shallow, coastal regions, others live in deep waters, on the ocean floor and in the open ocean. Some species, like the bull shark, are even known to swim in salt, fresh and brackish waters.
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- Sharks have evolved in a tight inter-dependency with their ecosystem. They tend to eat very efficiently, going after the old, sick, or slower fish in a population that they prey upon, keeping that population healthier. Sharks groom many populations of marine life to the right size so that those prey species don’t cause harm to the ecosystem by becoming too populous.
The ocean ecosystem is made up of very intricate food webs. Sharks are at the top of these webs and are considered by scientists to be “keystone” species, meaning that removing them causes the whole structure to collapse. For this reason, the prospect of a food chain minus its apex predators may mean the end of the line for many more species. A number of scientific studies demonstrate that depletion of sharks results in the loss of commercially important fish and shellfish species down the food chain, including key fisheries such as tuna, that maintain the health of coral reefs.
- Predatory sharks prey on the sick and the weak members of their prey populations, and some also scavenge the sea floor to feed on dead carcasses. By removing the sick and the weak, they prevent the spread of disease and prevent outbreaks that could be devastating. Preying on the weakest individuals also strengthens the gene pools of the prey species. Since the largest, strongest, and healthiest fish generally reproduce in greater numbers, the outcome is larger numbers of healthier fish.
- Sharks keep food webs in balance
- Sharks keep prey populations healthy
- Sharks keep sea grass beds and other vital habitats healthy