Everyone knows that sharks live in the water, but you may not know many other details about sharks and their habitats. Sharks can be found in all five of the Earth’s oceans: the Atlantic, Pacific, Indian, Arctic and Southern. These creatures can also be found in freshwater lakes and some rivers; for example, the bull shark is known to travel great distances up the Amazon River. Unlike many other animals, sharks aren’t territorial by nature, so they tend to change their habitat quite often. One of the biggest factors in determining where a shark will migrate is water temperature.
Sharks and Water Temperature
Sharks may be classified by the surface temperature of the water that they inhabit. The three major classifications are tropical, temperature and polar.
Polar sharks live in oceans near the polar ice caps. These sharks have adapted to survive in frigid waters that are only a few degrees above the freezing point. Examples of polar sharks include the black dogfish shark and the Greenland sleeper shark.
Temperate sharks live in waters that lie between these polar and tropical regions. Larger temperature sharks, like the great white shark and the basking shark, sometimes venture out of the temperate ocean zone and migrate to tropical waters; smaller temperature sharks can’t handle such drastic changes in water temperature and stay within regions where the temperature is more comfortable for them.
Common Shark Habitats
Different species of sharks will be found in different habitats around the world. The following list provides a few examples of habitats where you’re likely to find sharks:
Estuaries: An estuary is a body of water found in locations where rivers meet oceans. A variety of sharks can be found in this brackish mix of saltwater and freshwater, including sandbar sharks and lemon sharks. Lemon sharks tend to dwell in a type of tropical estuary called a mangrove swamp. These swamps are teeming with crabs, shrimp and small fish that provide a steady diet for young lemon sharks, and the mangrove roots found in these estuaries offer a safe place for newborn sharks to hide from predators.
Rocky coastlines: A rough, rocky coast may not seem like a hospitable environment for ocean life, but a diverse variety of species live beneath the surface. Tiny sea creatures seek shelter among the rocks, and algae and coral flourish here. This steady food supply attracts multiple species of sharks, including spiny dogfish sharks, white sharks and scalloped hammerhead sharks. The spiny dogfish shark is often described as an “underwater rat”, but its smaller size doesn’t prevent it from being a successful predator. Its sharp teeth and powerful jaws allow it to take bites from species much larger than itself.
Sandy plains: The shallow regions that comprise most of the continental shelf are known as sandy plains. These sandy, muddy areas support a wide variety of marine life, including small fish and crustaceans. Angel sharks, great hammerhead sharks and saw sharks thrive in the sandy plains, sniffing out prey even when it’s buried in the mud or sand. The angel shark acts as an “ambush predator”, hiding itself in the sand to make itself invisible to prey and lying in wait for days on end. Its jaws snap like a bear trap and make quick work of most small prey after a typical ambush.
Coral reefs: Although coral reefs inhabit just a tiny sliver of the earth’s surface, these structures are home to over 25 percent of the planet’s sea life. Gray reef sharks, Caribbean reef sharks and zebra sharks tend to live near coral reefs, feasting on the diverse marine life found in these communities. Zebra sharks have sleek bodies that can squeeze into coral crevices to hunt their prey. They usually hunt at night and spend their days resting on the ocean bottom.
Open ocean: Over 300 million cubic miles of the ocean are classified as the “pelagic zone”: the open water that’s far from the shore. In this region of the sea, fish tend to move about in large schools, and they can be difficult to catch. Sharks that live in the pelagic zone have adapted to become extremely fast-moving, able to catch their prey with swift movements. Blue sharks, thresher sharks and shortfin mako sharks are just a few examples of species that thrive in the open ocean. The shortfin mako shark is an especially fast-moving species and has been observed reaching a swimming speed of 50 miles per hour.
Deep ocean: The ocean has an average depth of 2.5 miles, and the deepest parts of the sea are rich with unusual-looking creatures. The goblin shark is one common inhabitant of the deep ocean; it earns it name from its eerie, elfin appearance, and it’s often referred to as a “living fossil”. Another denizen of the deep sea is the frilled shark. This species is rarely observed by humans and has a long, dark-brown body that resembles an eel. Its unusual body has evolved to meet the challenging requirements of the deep oceans.
Freshwater: Most people don’t envision sharks living in freshwater environments, but they do exist in some lakes and rivers. Bull sharks are the most common species of shark found in freshwater, but they need to travel to a saltwater environment in order to reproduce. They usually migrate to the brackish environment of a river’s mouth during mating season. Several shark species have been observed living full-time in the freshwater rivers of Australia and Southeast Asia.