Great White Sharks
Great white sharks are large mackerel sharks that are found in the surface waters of all the world’s major oceans. They can grow up to 20 feet (6.1 meters in length) and weigh up to 4,200 pounds (1,905 kilograms) when mature, with some living as long as 70 years or more. Great white sharks are a primary predator of a variety of marine animals, including fish and seabirds. They can swim at speeds of over 35 miles per hour (56 kilometers per hour) and to depths of 3,900 feet (1,200 meters).
The behavior and social structure of sharks are not well understood. They’re believed to hunt alone and have been known to bite one another if approached too closely. It is one of only a few shark species that lifts its head above the surface of the water to observe prey in a behavior known as “spy-hopping”. Great whites are carnivorous eaters. They feed on a diverse range of fish, cetaceans, sea turtles, and sea otters, as well as sea birds when the opportunity arises. They like prey with energy-rich fats and are renowned for their ability to detect blood in the water from great distances.
Cage diving with great white sharks has become a popular adrenalin activity in coastal regions frequented by the animals, including South Africa, Baja California, and South Australia. Many tourism operators chum the water with pieces of fish to lure the sharks. There is a concern by some that this is exacerbating the problem of unprovoked great white shark attacks on humans in the surrounding waters. Despite its reputation as a predator killer in “Jaws” and occasional attacks recorded on humans, great white sharks are listed as a vulnerable species by the IUCN. Also, they are protected by many governments around the world.
Killer (Orca) Whales
Killer whales (also known as orcas) are the largest member of the oceanic dolphin family. They can grow up to around 30 feet (9 meters) in length and weigh up to 14,550 pounds (6,500 kilograms). Their large size and strength allow them to reach speeds over 35 miles per hour (56 kilometers per hour). While this is similar to great white sharks, they can sustain these speeds over greater distances. Orcas can be found in all of the world’s oceans, including the Arctic and Antarctic regions. They socialize in matrilineal pods that are among the most stable of any animal species.
Killer whales are renowned for their sophisticated hunting techniques, with their prey including seals, dolphins and baleen whale calves. Some populations are considered threatened or endangered by the IUCN due to habitat loss, prey depletion, and pollution. In some cases, orcas have also been captured for use in marine theme parks. It is in these settings only that attacks on humans have been recorded. Killer whales have long been intertwined in the mythologies of indigenous peoples. Some groups revere them as the souls of humans, while others believe they are merciless killers.
Generally speaking, there are three different types of killer whales. Some scientists believe they may be distinct enough to be separate subspecies:
Resident killer whales are those most commonly sighted along the coast, and they return to the same areas year after year. They feed primarily on fish and squid in family pods and are characterized by their rounded dorsal fin, which ends in a sharp corner.
Transient killer whales roam widely along coasts and travel in smaller groups. They are also referred to as Bigg’s killer whales after cetologist Michael Bigg. Transient killer whales feed on marine mammals such as seals and sea otters and have a more pointed dorsal fin compared to resident killer whales. They also exhibit a solid grey or white area around their dorsal fin that’s known as the “saddle patch”. This differs from resident killer whales whose patch exhibits some black coloration.
The third type are offshore killer whales and were only discovered as recently as 1988. As a result, they are the least studied of the three groups. They travel and feed far from coastal areas in large groups of up to 200 individuals. However, they appear to be smaller and with a continuously rounded dorsal fin tip that distinguishes them. While they feed primarily on schooling fish, it is also believed that they eat marine mammals and sharks. It is these killer whales that are thought to be the culprits in the great white shark attacks seen recently in South Africa.