Sharks - Friend or Foe?

People tend to think about sharks in one of two ways. Either they fear sharks intensely or they are completely fearless and see them as harmless animals they can pet. Probably the most realistic view of sharks is somewhere in between. The vast majority of shark species are completely harmless to humans, but there are some that when provoked or mistake humans for prey can cause injury.

Sharks, members of the phylum Chordata, have skeletons of cartilage and occur in a variety of shapes and sizes. In addition to their tough skin, all sharks are equipped with streamlined bodies, allowing them to swim effortlessly through the water. The teeth of sharks are calcified and are lined in several rows in their jaw. The difference between sharks that will do damage to humans and those that are harmless can be linked to the type of teeth they have. Sharks, such as the infamous Great White, have large triangular shaped upper teeth with serrated edges used for tearing flesh, whereas non-threatening sharks have long, pointy teeth made for holding prey. Breathing is a challenge for sharks because they lack a gill covering; thus most have to move constantly in order to get oxygen from the water. As sharks move through the water they can detect electricity of every living thing around them through a series of tiny pores called ampullae di Lorenzini, allowing them to identify the presence of prey even in cloudy water. In the hunt for prey, sharks are also equipped with fairly good eyesight and an excellent sense of smell (sharks can detect blood in the water ? miles away). Of the 250 species of sharks, most prefer to roam in the open ocean and there is evidence of shark species associated with nearly every marine habitat.

Reef Brief is a weekly column published in the San Pedro Sun
The dominant shark species around San Pedro is the nurse shark (Eugomphodus taurus), and can be found in abundance around Shark Ray Alley, an area five miles south of town. These brown sharks are essentially harmless and tame; thus they are often caught and held by tourist guides out to impress their guests. This practice is increasingly discouraged because of the apparent harassment inflicted on the sharks. Due to the presence of the world's second largest coral reef, Black Tip Reef sharks (Carcharhinus melanoptenis) are also common in Belize. This species has a classic-shaped body and prefers to swim in the clear and shallow water found around reefs. Sometimes these harmless sharks can be seen jumping clear out of the water over patches of coral! Occasionally, these curious animals are attracted to splashing water and will nip on the fins of a passing snorkeler.

Perhaps the most famous shark of Belize is the Whale shark (Rhincodon typus). Known as the largest fish in the world, this shark can reach the length of 45 feet with a mouth opening four feet wide! Despite its intimidating presence, the whale shark has no teeth and feeds only on plankton; thus, it is not a threat to humans.

In addition to the three above species, both Lemon sharks and Hammerheads can be found in Belize. There is still much to be learned about the fascinating biological and behavioral aspects of all sharks. Today, sharks are frequently hunted for sport, leading to the endangered status of some species. Only when we learn more about these amazing animals and let go of irrational fears of what they may do to us can we begin to appreciate them.

Like all living things in the sea, sharks play an important role in the ecosystem (especially in the food chain) and for this reason they should be respected.

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