Sharks in African Waters 

Our location was Protea Banks - a deep reef eight kilometres off the southern coast of KwaZulu-Natal in South Africa. It was midwinter, a time when millions of sardines leave the cooler waters of the Cape and move northwards, en masse, taking with them an entourage of pursuing predators, including sharks. Revelling in the feast, as we arrived at the dive site, were copper sharks. But they weren't the focus of our expedition. We wanted to film the sharks that, we hoped, were on the reef below.

Twenty metres down, we perceived the outline of the reef. Five metres closer and we distinguished many dark shapes moving slowly over it - at least 60 ragged tooth sharks, or sand tigers, were peacefully floating above the coral. Shifty-eyed, they accepted us among them. With a permanently open mouth lined with rows of jagged teeth, this shark seems the embodiment of a lethal and terrifying predator. But it's not. Every winter, South African divers look forward to "Raggie season", whenthey can dive with these seemingly placid sharks.

"Raggies" (as they are affectionately called by divers) migrate from their cool-water summer habitat to the reefs off KwaZulu-Natal to breed. Although no diver has ever witnessed mating, we know that it is a violent affair. In fact females have evolved a thicker skin to cope with the bites given by the males. The violence within the species continues in the mother's womb during the nine-month gestation period. In her two separate uteri the developing shark pups eat each other until there's only one left in each uterus. This gruesome act is known as intra-uterine cannibalism.

Not all sharks' unborn are so vicious. The embryos of the Zambezi or Bull shark develop within their mother nourished by the food in the maternal blood, in a manner similar to that of mammals. After a gestation period of a year the mother looks for a safe estuary on Africa's south-eastern coast to give birth. Her strategy serves two purposes: her young will be safe from adults and other predatory sharks that live in the Indian Ocean, and the youngsters do not have to compete for food in the sea. Most young reach maturity within the fresh waters of the river, sometimes venturing far upstream. Zambezi sharks have been seen as far as 1200km up the Zambezi River.

When the young adults leave the estuary for the sea, they become members of a species dangerous to man, as their favoured hunting grounds are the murky waters near river mouths and along African beaches. The Zambezi shark has been responsible for more deaths in South African waters than any other shark species - even the Great white.

The Great white shark's reputation is mythical in proportion, resulting in the unjust slaughter of many individuals. This has diminished numbers so alarmingly that, eventually, the species became officially protected in South Africa waters. At last the Great white shark was acquitted. It was never the relentless killing machine it was made out to be by the media.

While at a seal colony on a group of small islands, filming for a documentary on Great whites off Gansbaai in South Africa, we noticed that this shark was almost shy and reserved. According to its reputation this should have been a killing field. The islands support more than 70,000 seals who hunt and swim daily in the small channels in between. Yet we were extremely lucky to see a shark actually killing a seal.

When hunting, the Great white swims close to the rocky bottom, its dorsal, grey coloured blending in with the mottled shades of the channel floor. Once it has chosen its victim it propels itself upwards with incredible speed. As its mouth gapes open to grab the ill-fated seal, a thin membrane moves over its eyes to protect them during the attack. With a 44,000 pound-per-square-inch bite pressure, there's no escape for the prey.

But sharks don't always use the full potential of their bite. Having no hands they use their mouths to feel foreign objects. We had placed an underwater camera over the side of the boat to film the sharks swimming past when one, more curious than the rest, bit the camera. The teeth left no marks in the aluminium housing.

I once interviewed a spear-fisherman who was bitten by a Great white shark, but he thought that the shark only bit through his body after he inflicted pain on it. Before that, the shark had merely grabbed him in a sturdy but gentle grip and dragged him underwater.

Sharks have been on Earth far longer than dinosaurs. They were swimming in ancient seas more that 415 million years ago. Since the time of the dinosaurs, 60 million years ago, little of the shark's basic design has changed - they are the most ingeniously designed predators of the earth's oceans. Today, of the 370 or so known species of sharks, only 25 are potentially dangerous to man and the largest of sharks is also the most gentle of giants. Reaching lengths of up to 18m, the whale shark is the largest fish in the sea but it feeds on the smallest of prey: plankton.

It spends its days following the currents of the oceans looking for concentrations of its favourite food. Once it finds clouds of plankton it opens its mouth wide and filters incoming water through specially designed gill rakers that separate plankton from the water. During the day whale sharks are generally found near the ocean surface and around Africa they can be seen swimming slowly along the entire east coast, from the Red Sea to the southernmost tip of Africa. Recent satellite tagging programmes have revealed that at night these gentle giants dive to incredible depths, exceeding 100m. We can only speculate why - could they be accessing deep sources of food?

Another mysterious creature in the lineage of shark species is the hammerhead shark, particularly the schooling scalloped hammerheads. There are only a few sites worldwide where they may almost certainly be observed during specific periods of the year; in Africa there is one particular dive site in the Red Sea, off the coast of Sudan, called Sha'ab Rumi. Here, silent squadrons swim up from the blue depths and hover over the sea-mound.

Recent studies have revealed that the "hammer" houses the most elaborate and highly developed electro-receptors of any of the shark species. All sharks have a special electricity-detecting organ called the ampullae of Lorenzini situated in their snouts, which enables them to detect one-millionth of a volt. This makes them incredibly acute, able to detect the tiniest of charges produced by the nerves of a fish's body. In hammerhead sharks, it is thought that this ability is especially refined.

Through evolution, many shark species developed, altered or perfected certain physical characteristics to suit their way of life. The hunters like the Great white and the Silvertip sharks streamlined their bodies for quick mid-ocean hunting, their fins designed for speed and teeth developed for grabbing and tearing. Some sharks chose a more placid and sedentary lifestyle, preferring to rest on the bottom waiting for prey to come to them. These sharks, like the ragged-tooth, have developed the ability to pump water over their gills to breathe without having to move. Another species that can do this is the leopard shark.

When filming for a documentary on sharks off Mozambique at a resort called Barra Lodge, near the town of Inhambane, we decided to explore a new reef further out to sea. We descended 25m to a beautiful coral-covered ledge, clearly untouched and unspoilt by human interference, and noticed something large lying on the sandy floor beyond. It was a two-metre leopard shark (one of my favourite sharks) placidly pumping water through its gills. Suddenly it raised itself off the floor, quickly moved over the sand and plunged its face into it, seemingly blowing sand away. We realised it was feeding. Leopard sharks eat molluscs and crustaceans found buried in the sand. Their mouth parts have evolved into perfect crushing tools and their teeth have fused into hard plates to do this efficiently. Once it had finished eating it turned and realised it was being watched but, instead of fleeing alarmed at our presence, it came towards us. For the duration of the dive it followed us like a puppy. It was an overwhelming experience, knowing that the shark chose to stay with us rather than flee.

It's sad that such an incredible species is so misunderstood and generally known worldwide only for its commercial value. Every year thousands of sharks are slaughtered for their meat, skin, fins, liver oil and cartilage - a tragic end for a creature that has ruled the Earth's oceans for over 400 million years.

Although much more work has to be done to reach the programmed psyche of the general public and the shark hunters, there are some people, especially divers, who are beginning to understand and enjoy the experience of a shark encounter. For now, only a handful of countries see the importance of protecting the shark species. We can only hope that in the future more will see it too.

Johannesburg based Stefania Lamberti is a successful underwater photographer and expert on sharks. She runs a film company making wildlife documentaries.

Published in Travel Africa Edition Fifteen: Spring 2001 Text is subject to Worldwide Copyright (c)