Not terribly long ago, feelings of terror were almost always associated with sharks. The idea that man-eating sharks lurked beneath the surface waiting for hapless victims was definitely influenced by the movie “Jaws.” Peter Benchley, who authored the book by the same name, realized that he hadn’t painted the best picture of sharks with his writing; today, he is an ocean activist who works diligently for shark conservation causes. In addition, he is on the board of advisors for environmental Defense on Shark and Marine Fisheries issues.
The largest sharks in the ocean are often referred to as gentle giants; that’s because two of the largest species, the whale shark and basking shark, are plankton eaters. They do consume small fish along with the plankton they gulp up, however this is not hunting activity. These sharks are just not interested in eating people, mammals, birds, or large fish of any kind.
This moniker might as well be extended to include many more of the 475 shark species or so which roam the seas; of all these, only four types have been known to aggressively attack human beings, and all known attacks have occurred when the shark has been confused over the shape of an item such as a surfboard or a kayak, or when the shark has felt threatened. The four species involved in attacks are the Great White Shark, the Tiger Shark, the Oceanic White Tip Shark, and the Bull Shark.
It’s a sad and sorry fact that human beings are more of a threat to sharks than they are to us. Their very existence is threatened by human activities including fishing and shark finning. Habitat loss, loss of prey, and pollution are some additional risks sharks face each day in their ocean homes.
To stay safe while diving in areas where shark encounters are common, there are some general rules you can follow. These include:
- Never follow or touch a shark
- Don’t get into a shark’s space; keep a respectful distance
- Avoid the water if bleeding
- Do not wear shiny objects that could be mistaken for prey
- Stay with your group
- Stay out of the water at dawn, dusk, and after dark
- Do not feed sharks
In addition, if you are diving from a kayak, keep a close watch for sharks and carry shark repellent. Sharks are often fooled by the shape of the kayak, believing that it is a seal or sea lion when viewed from below.
Shark Basics
Sharks are fascinating creatures. Knowing more about them can help you to gain affinity for them and understand their behavior.
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A shark’s skeleton is made up of cartilage; unlike many other fish, these animals do not have rib cages. When on land, their own weight can crush their internal organs.
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Shark jaws have layers of hexagonal plates which provide it with support and strength. The bull shark, tiger shark, and great white shark have two to three layers of plates, while the white shark has as many as five layers of plates.
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A shark’s teeth are replaced throughout its lifetime; it’s estimated that some sharks go through as many as 30,000 teeth during their lives. The shape of a shark’s tooth can provide clues about its diet.
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It’s impossible for a shark to swim backwards – its’ fin shape prevents it from doing this.
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Different shark species have different-shaped tails. A shark’s ability to accelerate, as well as the level of speed it can reach depends on its tail.
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Sharks have huge livers which are full of oil. These organs help the animals to maintain their buoyancy.
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Most sharks need to keep swimming to breathe, so they do not really sleep; you’ll see them “napping” in sheltered areas, but even then, you can perceive slight movements which help to keep them afloat.
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Sharks have a set of spiracles behind the eyes; these also known as gill slits. Most sharks have between five and seven gill slits.
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Most sharks have an internal body temperature which is the same as their external body temperatures; only the great white shark and mako shark are known to have higher internal body temperatures.
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Sharks have strong senses; their smell, hearing, and eyesight are powerful.
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Sharks have electrical receptors on their heads which aid them in detecting prey.
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Sharks are equipped with a special organ called the lateral line, which helps them to detect vibrations in the water.
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The average shark has a twenty to thirty year life span
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Almost all sharks live in saltwater. The river shark and bull shark can live in either fresh, brackish, or salt water; these two species can move far up large rivers in areas where they are known to live.
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Sharks generally migrate long distances to mate and feed; migration is believed to be seasonal.
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When a shark feels threatened, it will make exaggerated swimming motions which will intensify as the threat to the animal increases. If you see a shark making strong movements in your vicinity, move away slowly and stay calm.
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Sharks have specialized skins with dermal denticles. These apparatus help the shark to swim rapidly; they also help to protect the skin from damage and keep parasites from hanging on.
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As a rule, sharks are carnivorous.
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Sharks mature slowly. They also reproduce slowly, giving birth to only a few healthy offspring throughout their lives.
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Sharks are smarter than we gave them credit for in the past. They are social, playful, and capable of solving problems.
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The average speed of a shark is 8 kilometers per hour; this speed increases to as much as 19 kilometers per hour when attacking or feeding.
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Great white sharks are aggressive and have instilled fear in people because they do have the capacity to attack humans. However, they attack only when they feel threatened and when they feel the need to protect themselves. The great white shark is the only shark species that will bring its head up out of the water to look around; it has a pointed nose and rows of huge white teeth, which give it a truly fearsome appearance.
While it’s true that some sharks are aggressive; most, though, are shy and retiring. Remembering that we are visitors in the shark’s world and treating these magnificent animals with respect goes a long way toward preventing shark-related diving accidents.