Sharks are among the oldest species on the planet. The oldest sharks lived over 420 million years ago. This was before most land animals existed. They were alive during the time of the dinosaurs (large extinct reptiles) and outlived them. The oldest prehistoric sharks would look very different to today’s sharks. However, for the last 70 million years they have remained largely unchanged. African waters hold some of the most famous and deadly sharks to have ever existed.
Also known as bull sharks, these are one of the most aggressive living sharks. Generally a solitary hunter, they primarily eat bony fish and smaller sharks. Zambezi sharks are one of the only sharks to be diadromous. This means they can live in both freshwater rivers and the salty ocean. This is partly because zambezi sharks can regulate the amount of salt in their body by controlling its release by their organs. Salt is more likely to be released from the body in freshwater as there is less salt in the water.
If you spot a zambezi shark in a river, it will likely be young or pregnant. Infants need time to develop this tolerance to salty water. When they are ready to mate they will migrate (move) to the sea. Pregnant zambezi sharks return to rivers to give the intolerant babies a better chance at survival. Rivers are also safer as there are fewer predators.
Zambezi sharks in the sea prefer shallow coastal waters. This is where they hunt. Remember to keep an eye out for these sharks here and in rivers, as they are one of the top four most dangerous sharks.
GREAT WHITE SHARKS
Great White sharks are listed as the most dangerous shark to humans. They are found in large groups around Dyer Island and Seal Island in South Africa. Great Whites have been in African waters for 16 million years.
Great Whites are known for their unusually long migrations. One African shark swam to Australia and back in under nine months. This was likely due to seasonal hunting or mating. Resistant and powerful, these sharks can grow over 6 meters long.
Many people know great whites for shark attacks on humans. There is a mistaken belief that sharks deliberately hunt people. Most shark attacks are cases of mistaken identity, as sharks attack from below. This means that sharks confuse swimmers for seals, their main prey. Shark attacks mainly occur at sunrise and sunset, as this is when great whites hunt. To be safe, avoid the ocean at these times.
Other dangerous African ocean sharks include tiger sharks and oceanic whitetips. These four sharks mentioned make up the four most dangerous sharks to humans. Oceanic Whitetips engage in ‘feeding frenzies’. This meant that following a shipwreck in 1945 in Africa waters, 1000 of its passengers were killed by these sharks. Most other African sharks are not dangerous to humans. The whale shark, despite being the largest shark, only eats plankton. These are tiny sea creatures.
The megalodon is an extinct prehistoric gigantic shark. It lived from around 23 to 2.6 million years ago. Although scientists debate whether it was a direct ancestor to great white sharks, it would have looked similar to them. We know this because of megadolon fossils (bones) and teeth.
It was much larger than a modern great white, reaching up to 17 meters. This gigantic shark preyed on large animals such as whales.
THREATS TO SHARKS
Although sharks are the world’s most powerful water-based predators, many are endangered because of humans. They have lived millions of years, but due to over-fishing and ocean habitat destruction sharks may soon die out.
Shark finning is the practice of removing fins from sharks, for foods like shark fin soup. The practice has increased since 1997. Although eaten, shark fins have very few nutrients. This means there are little benefits to eating shark fins. All four living sharks we have discussed are killed for their fins, and are endangered.
Sharks are also killed for fun, or because they are seen as a threat. In reality, around 5 people are killed by sharks per year worldwide. This is much less than the 22 killed by cows. To prevent any possible threat, avoid splashing or wearing bright colours that will attract hungry sharks. Also avoid wearing metal jewellery, as when light reflects off of the metal, sharks may mistake it for fish scales.