Sharks are a group of fish characterised by skeletons made of cartilage and light flexible tissue. Sharks are currently diversified into over 470 species, with the largest shark/fish in the world being the Whale shark. Though sharks are generally not found in freshwater, exceptions like the Bull shark and River shark can be found in both seawater and freshwater. The general view about sharks describes them as solitary and vicious hunters, but this is applicable only to a few species. A few well-known sharks encountered frequently at diving destinations around the world are listed below:
Bull sharks are quite common and quite aggressive, often found near high-population areas like tropical shorelines. Unlike most sharks, they can swim in both seawater and freshwater and sometimes even stray far inland up rivers and tributaries. A short, blunt nose, a confrontational disposition and a tendency to head butt its prey gives this shark its name. The bull shark is medium sized and has a thick stout body with long pectoral fins. These sharks generally do not attack humans, but may be aggressive due to curiosity.
The bull shark frequents the shallow waters of the oceans. Due to their preference for shallow water close to the shore and in rivers, they are found in close proximity to humans. Bull sharks can be found at dive sites like Andros, Berry Islands, Nassau and Bimini in the Bahamas; Cancun and Puerto Morelos in Mexico; the Cocos Island and Playas del Coco in Costa Rica; and Beqa Lagoon in Fiji.
Great White Shark
The Great White shark is a legendary creature, more fearsome in imagination than in reality. The Great White shark’s image as a ruthless killer is slowly disappearing after scientific research on its behaviour. They have slate-gray upper bodies, which fit in with the rocky coastal sea floor, while deriving their name for their white underbellies. At fifteen feet long, they are the largest predatory fish on Earth. Similar to whales, they occasionally leave the water and breach the surface to attack their prey from underneath. Although it does not prey on humans for food, it often mistakes humans for seals or otters, which is the major cause of attack on humans.
These sharks can be spotted in cool coastal waters throughout the world, but there are only four places where a diver can go cage diving with these sharks. These four famous dive sites are False Bay/Seal Island in South Africa, Isla de Guadalupe in Mexico, Farallon Islands in California and the Neptune Islands in South Australia.
The Whale shark is the biggest fish in the sea and grows to lengths of forty feet or more. Even though they have an enormous menu to choose from, they prefer eating plankton and consume them by scooping the tiny creatures with their huge gaping mouths. They feed by a process called filter feeding, thrusting out their jaw and passively filtering the water flowing into the mouth for food.
Preferring warm waters, whale sharks can be found in all the tropical oceans and seas. The whale shark is a migratory species and migrates every spring to Australia’s west coast. They can be spotted by divers and snorkellers at locations like the Bay Islands in Honduras, Coiba Island in Panama, Holbox Island in the Caribbean Sea, Koh Tao in the Gulf of Thailand and Maldives.
Grey Reef Shark
One of the most common reef sharks, the Grey Reef shark is frequently spotted in the Indian and Pacific Ocean. They have broad, round snouts and large eyes. These fast swimming agile predators feed extensively on bony fishes and cephalods.
A coastal, shallow-water dwelling species, the Grey Reef shark is found at depths of less than sixty metres. They make up one of the three most common sharks inhabiting the Indo-Pacific reefs and are found at dive sites like Muri Muri and Tapu Dive in French Polynesia, Middle Point and Cocoa Corner in Maldives and Sharm el Sheikh in Egypt.
Named for their dark vertical stripes, Tiger sharks have earned a reputation as fearsome man-eaters, and are second only to the Great White sharks in the number of attacks on humans. The Tiger shark is usually between two to four metres long, though it can grow up to eight metres.
These scavengers have a brilliant sense of smell and sight and an almost unlimited diet, as proved by stomach contents of captured Tiger sharks containing sea snakes, squids, seals, birds and also license plates and tires. Tiger sharks are common in tropical and sub-tropical waters throughout the world, with sightings at various diving sites like Shark Alley, Tiger Beach, Cat Island in the Bahamas, Hurghada in the Southern Red Sea in Egypt and Anquar and Blue Corner in Palau.
Great Hammerhead Shark
Hammerhead sharks are aggressive hunters that use their visual prowess improve their ability to find prey. Gifted with a better visual range than other sharks due to their wide set eyes, these sharks use their hammer-shaped heads to find prey. They are coloured gray-brown to olive green on top and sport grey-white underbellies, along with highly serrated triangular teeth.
Although their enormous size and fierceness makes them potentially dangerous, the Hammerhead rarely attacks humans. They are found in temperate and tropical waters worldwide and are often seen in mass summer migrations seeking cooler water. Diving locations where Hammerhead sharks are sighted frequently include Gordon Rocks and Enderby in Ecuador, Punta Maria and Bajo Alcyone in Costa Rica and Big Island in Hawaii.
The Nurse shark owes its name to the sucking sound it makes while hunting for prey. These slow moving sharks are bottom-dwellers and are for the most part harmless to humans. The Nurse shark is gray-brown and has prominent tail fins that can be up to one-fourth their total length. They are nocturnal creatures and usually rest on the sea floor in groups of up to forty sharks, sometimes piled on top of each other.
They are found in the warm, shallow waters of the western Atlantic and eastern Pacific oceans in diving sites like Shark Buoy and Cat Island in the Bahamas, Shark Cave in Tahiti, the Blue Holes in Palau and Silverado in Costa Rica.