Sharks: Myth vs. Reality
Sharks are among the most feared animals on the planet. They inspire both awe and terror, and prevent some people from going into the ocean beyond knee-deep water. However, this reputation is inaccurate and unjust. There are very few shark attacks reported each year, and only a handful of shark species have ever been known to attack humans. Although almost all sharks are carnivores, some of the largest species prey on nothing bigger than plankton, a microscopic organism that drifts freely in the open ocean. In fact, a shark is far more likely to be killed by a human than the other way around. Millions of sharks are killed by fishermen each year, dramatically reducing shark populations worldwide. And without conservation efforts, the future of many shark species is uncertain.

Kings of the Ocean
Sharks live in just about every saltwater habitat and occur in all of the world’s oceans. They first appeared on earth about 400 million years ago, long before the age of dinosaurs. There are about 375 different species of shark, ranging in size from just a few inches to about as big as an 18-wheeler. They are different from other groups of fish in that they have skeletons made of cartilage instead of bone, skin that feels like sandpaper, and continuously regenerating teeth, with new ones replacing the old as they loosen and fall out. Sharks also lack a swim bladder, the gas-filled structure that gives fish buoyancy. Instead, sharks move through the water in a wavelike fashion or rely on their tails to propel them forward. It is because of the lack of a swim bladder that a shark will sink if it stops swimming.

Sharks have a variety of features that make them extremely successful predators. For example, they have very good eyesight and an excellent sense of smell. They can also detect the vibrations of their prey in the surrounding water using the ultrasensitive lateral line that runs the length of their bodies. And if all of those methods fail, sharks can pick up the weak electrical charges produced by other animals through the pores of their skin, allowing them to find prey in total darkness.

Despite the unlikelihood of being attacked by a shark, there are a number of things that people should do to avoid an encounter with a shark. First, check the beach warning signs for shark sightings. Don’t swim alone, at night or when there is no lifeguard on duty. Also, look for and avoid fish or fish bait in the water. This could mean that sharks and other predators are nearby. Don’t swim when the water is murky, such as after a heavy rain. And try not to swim if you have cuts or are bleeding in any way. Sharks are very sensitive to the smell of blood. They are also attracted to jewelry and brightly colored clothing or anything that makes you look like a delicious tropical fish. If you do see a shark, don’t panic; leave the water quickly and calmly and inform a lifeguard immediately.

Cocos Island: A Shark Haven
Cocos Island, located about 300 miles southwest of Costa Rica in the Pacific Ocean, is a tropical island with a rugged coastline and an astonishing degree of biodiversity. It is a favorite destination for marine biologists, scuba divers and anyone with an appreciation for natural wonders. In addition to being a Costa Rican national park, Cocos Island is a World Heritage Site because of its unique wildlife-rich environment. The waters of Cocos Island provide critical habitat to a bounty of exotic fish, many of which are endemic, as well as dolphins, eels, sea turtles, hammerhead sharks and silky sharks.

The Hammerhead: An Ocean Oddity
Cocos Island is known worldwide for its populations of hammerhead sharks, a particularly fierce species that gets its name from the shape of its head, which looks very much like a hammer. Hammerheads are found in open ocean as well as shallow coastal waters. They are migratory sharks, with schools traveling to the tropics in the winter months. In Cocos Island, schools of hammerheads are often observed by divers in the undersea mountains just off the coast. They are considered to be one of the few shark species that can be dangerous to humans.

There is a great deal of speculation about hammerhead shark anatomy. What could be the purpose of such an oddly shaped head? Many believe that hammerheads give the shark increased speed. Some theorize that the hammerheads are used in mating rituals. Others believe that it helps the shark to track and pin down prey. Whatever the original function, hammerhead sharks have certainly become successful hunters, preying on fish, crustaceans, rays and other sharks.

Sharks in Peril
Sadly, shark populations around Cocos Island have declined drastically in recent years. Overfishing is the primary reason, but sharks also get caught in fishing nets and trawls set for other species. This is especially true of silky sharks, another species found in the waters of Cocos Island. But perhaps the main reason for the decline in shark populations is "finning," a particularly destructive and wasteful fishing process in which fins are removed from the shark and the remainder of the body is thrown overboard. Finning has increased in recent years due to the rise in popularity of shark fin soup, an Asian delicacy.

About 25 percent of the known species of shark are under threat of extinction. Sharks have long gestation periods, low numbers of offspring and slow growth rates. These factors combine to make it extremely difficult for them to recover from population declines. The impact of depleted shark numbers on marine ecosystems is difficult to gauge but will undoubtedly upset the delicate balance between predator and prey in the global oceans. Unless the destructive fishing practices are stopped and shark protections are put in place, we risk losing these ancient and awe-inspiring animals forever.

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Take action now to help put an end to shark hunting in Cocos Island!