Tuesday, August 15, 2006

Animal Encounters XI

The Great White Shark

The great white shark is a streamlined swimmer and a ferocious predator with 3,000 teeth at any one time. This much-feared fish has a torpedo-shaped body, a pointed snout, a crescent-shaped tail, 5 gill slits, no fin spines, an anal fin, and 3 main fins: the dorsal fin (on its back) and 2 pectoral fins (on its sides). When the shark is near the surface, the dorsal fin and part of the tail are visible above the water.


Only the underbelly of the great white shark is actually white; its top surface is gray to blue gray. This is useful in hunting its prey. The great white usually strikes from below and its grayish top coloration blends in with the dark water, enabling it to approach the prey unobserved. Great whites average 12-16 feet long (3.7-4.9 m) long. The biggest great white shark on record was 23 feet (7 m) long, weighing about 7,000 pounds (3200 kg). Females are larger than males, as with most sharks. Shark pups can be over 5 feet (1.5 m) long at birth. Young great white sharks eat fish, rays, and other sharks. Adults eat larger prey, including pinnipeds (sea lions and seals), small toothed whales (like belugas), otters, and sea turtles. They also eat carrion (dead animals that they have found floating dead in the water). Great whites do not chew their food. Their teeth rip prey into mouth-sized pieces which are swallowed whole. A big meal can satisfy a great white for up to 2 months.

Shark going for the bait

The great white shark has 3,000 teeth at any one time. They are triangular, serrated (saw-edged), razor-sharp, and up to 3 inches (7.5 cm) long. The teeth are located in rows which rotate into use as needed. The first two rows are used in obtaining prey, the other rows rotate into place as they are needed. As teeth are lost, broken, or worn down, they are replaced by new teeth that rotate into place. Great whites are propelled through the water by their powerful tails. The fins are only used for balance. Their movement is more like an aircraft's flight than other fishes swimming. They can swim 30 miles per hour in short bursts. They swim constantly or they will sink since, like other sharks, they have no gas filled swim bladder to keep them afloat like bony fish do. Like other sharks, their large, oily liver provides some buoyancy, but they are still heavier than water and will sink unless they are propelling themselves through the water. Also like other sharks, they cannot swim backwards or even come to an abrupt stop, because their fins are not flexible like other fish. In order to go backwards, they must stop swimming and fall backwards, using gravity to propel themselves backwards. Great white sharks can also jump out of the water (called breaching). They jump into the air from deep water in order to catch fast-swimming seals.

Shark breach!

And its a male!

No one knows the life span of the great white shark. Some people estimate it to be about 100 years, but this has not been proven. Great whites are decreasing in numbers and are rare due to years of being hunted by man. They are a protected species along the coasts of California, USA, Australia, and South Africa.

Cage diving

The organisation I work with (White Shark Projects) undertakes much cage diving with sharks. This was originally thought of as a bad idea, as it was believed that by baiting humans in cages, sharks would associate humans as food, through the process of conditioning. However, this is disputed as sharks are highly nomadic animals, their territory ranging over vast areas, even across continents. Recently a female great white that was tagged in South Africa was found swimming of the coast of Southern Australia. And a couple of months later, she was back in South African waters. Personally, I see a different shark every time I go out on the boat. We get about 6-9 different sharks a day approaching our boat. Hence this and other research show that a shark would never stay in a place long enough to become conditioned. The organisation also disagree that cage diving is a dangerous on the basis that a shark cannot mentally seperate the human diver from the cage.

Note: Many thanks to Dean for his wonderful underwater camera and photography tips !

Update: There was a shark attack on a swimmer off False Bay, Cape Town, yesterday. He lost a foot.

Sunday, August 06, 2006


I'm now in Gansbaai, the world capital of the Great White Shark, with Dyer Island ( about 25km off Gansbaai) presenting the best place in the world to discover, observe and dive with these elusive and wonderful animals. From June through December, Gansbaai becomes home to the Southern Right Whale. This coastline and the many bays then become the breeding area for these giants of the Oceans. I've seen a couple a whales from the coast in the mornings when I go out to sea on the boat.

Gansbaai Harbour

Gansbaai itself is a very small fishing village. You can basically walk from one end of the village to the other in just 15 mins. It has a harbour where the fishing boats come in at about 2-4pm in the afternoon. The fishermen here fish a kind of fish (hope that sounds right) called Snoek. And you can also buy it fresh straight off the boat, where the fisherman will help you descale and fillet it.

Fisherman with Snoek

Descaling & filleting

Along with the fishing industry, Gansbaai has grown into a charming village and holiday resort. It has primary school, churches of various denominations and shops to provide for every need. Fishmongers are stocked with fresh catches daily. Gansbaai is a popular holiday resort for boating and fishing enthusiasts and whale watchers. Dyer Island near Gansbaai is a breeding colony for jackass penquins while seals breed on nearby Geyser Rock. There is a narrow channel in the sea between Geyser Rock and Dyer Island which is home to up to 60 000 Cape Fur Seals.

60,000 seals! Just imagine the smell!

The narrow channel is called shark alley. The sea around these islands have become the feeding ground of the endangered great white shark and regular shark safaris are undertaken from Gansbaai. Since the area around Dyer Island has been declared a nature reserve, boats may only enter this area with a permit given by the Department of Nature Conservation.

Shark cage diving!

I'm staying in a nice house by the coast. The view from my room is magnificent! It looks out to the sea. And I sleep and wake up to the sound of crashing waves!

Room with a view!

The winds and waves are very strong. Sea conditions can change in a blink of an eye. When there is a storm, it is like being in a middle of a hurricane, except the locals here just call it a storm. Many ships have run aground on the treacherous rocks around here, with the legendary Cape of Good Hope just around the corner (about 100 miles).

Treacherous swells