Sharks have been around for hundreds of millions of years and are among the deadliest creatures on Earth. Sharks can unhinge their jaws and destroy large prey with their rows of razor sharp teeth. But even though sharks' jaws and teeth make them fierce predators, it's their sensory perception that truly makes them great hunters. Sharks can track large prey by following their low-pitch sounds, plus they can smell blood in the water from miles away. Sharks also have two extra senses which allow them to sense electrical fields and vibrations in the water. So, even the slightest movement in the water can trigger a shark's predatory instincts.
Once a shark has sensed the presence of prey, it uses its incredibly strong tail to propel itself through the water. Sharks deftly maneuver through the water by adjusting the angle of their fins. Sharks don't have a swim bladder like most other fish, so they regulate their vertical position by moving forward. Another unique aspect of the shark's body is that its skeleton is composed of cartilage rather than bone.
Sharks tend to be loners, swimming and hunting by themselves. They occasionally travel in schools, but typically hunt alone. They sometimes follow the annual migration patterns of fish and even fishing boats in search of an easy meal, but sharks manage to find food in all circumstances. When food is scarce, they use camouflage along with their incredible speed to surprise their prey, making an escape almost impossible. The element of surprise is important to sharks because it is advantageous for them to kill their prey in one bite, which conserves their much-needed energy.
Sharks are rarely the prey of other aquatic predators, but they encounter numerous problems with fisherman, particularly in Asia, where shark is considered a delicacy. Over-fishing and accidental bycatch have dramatically reduced shark populations around the world. Those factors, along with sharks' infrequent mating habits and small litter size, are putting the shark population in jeopardy.
Interesting Shark Facts
- Shark species vary in length from a few inches to 45 feet.
- A great white shark could detect a single drop of blood in an Olympic-size swimming pool.
- Between 75 and 100 shark attacks are reported each year, but less than 20 result in human death.
- Some sharks can live to reach the ripe old age of 100! However, most sharks live about 25 to 30 years. Sadly, the shark's average lifespan is decreasing as a result of over-fishing and accidental bycatch.
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- Dehart, Andy. Personal correspondence. July 18, 2008.