Sharks are one of, if not the most widely recognized fish in our oceans. They invoke a wide range of emotions from fear to inspiration and everything in between. People that fear sharks and think of them as mindless killing machines don’t know a fraction of the story. Don’t let television drama fool you, truth is, you are more likely to be struck by lightning than be bitten by a shark. People that are bitten are usually mistaken for a normal prey item or are just in the wrong place at the wrong time. No matter your opinion of them, they are important to us and our oceans. Sharks are at the top of their respective food chains and regulate populations of species below thus keeping oceanic ecosystems in check.
There are more than 440 described species of sharks and they come in a variety of sizes. They range from the deep water dwarf Lanternshark, Etmopterus perryi, which maxes out at about 17 cm to the Whale shark, Rhincodon typus, which reaches approximately 12 m. Often identified by most people as a shark by their distinct fin structure, the modern shark as we know it has been around for roughly 100 million years. Although they looked very different than modern day sharks, fossil evidence has been found that shows sharks existing roughly 420-450 million years ago.
Shark diets vary and include crustaceans, invertebrates, other fish, plankton, mammals and even the occasional sea turtle. An individual shark’s diet can generally be identified by its teeth that are constantly being replaced throughout its lifetime. Although they also eat other items, flattened teeth like those of the Leopard shark, Traiakis semifasciata, are generally used for crushing prey like crabs, shrimp and clams. Needle like teeth like those of the Sand tiger or Spotted ragged-tooth shark, Carcharias taurus, are used for gripping fish that are captured. Sharks that eat larger prey like the Great white, Carcharodon carcharias, have a combination of angular and pointed teeth with serrations that can be used gripping, cutting and tearing. Oddly enough the largest of the shark species, the Whale shark, Rhincodon typus, eats plankton and has small nonfunctional teeth. In order to find their prey over long distances, they utilize an electro sensory system. Once the prey is located, sharks can then combine this with their smell, hearing and vision to home in.
Shark bodies are all about saving energy and maximizing efficiency. Their structure is maintained by cartilage rather than bone which is durable, flexible and is about half the density of bone. Their skin is a complex weave of flexible collagenous fibers arranged in a helical network surrounding their body. This structure acts as an outer skeleton and provides attachment for their swimming muscles as well as gives them hydrodynamic advantages by reducing turbulence when swimming.
Like many fish populations, most shark species face high amounts of pressure from humanity making encounters with them less and less likely. There are however locations where people can go to see significant shark populations such as the Caribbean, the Galapagos and Cocos Islands. The populations of sharks in these locations can be breath taking and of course provide fantastic photo opportunities. Fun shots of sharks can include close ups, silhouettes, feeding, schooling and even shots of sharks employing camouflage. Before you start taking pictures, take time to watch and appreciate these majestic animals, you’ll be glad you did.
Lemonshark and tigersharks in Bahamas
By Sven Hewecker
