Sharks — Misunderstood Predators

Sharks are some of the most amazing animals on Earth. They have lived in our oceans for more than 450 million years — that is longer than trees have existed on land! Scientists have discovered more than 500 different species of shark. Some are tiny, like the dwarf lanternshark, which is small enough to fit in your hand. Others are enormous, like the whale shark, which can grow up to 12 metres long — about the same length as two school buses.

Sharks live in every ocean in the world. Some prefer warm, shallow water near beaches. Others live in the deep, cold parts of the ocean where it is completely dark. Some sharks, like the bull shark, can even swim into rivers and live in fresh water for a time.

Sharks are fish, but they are very different from most other fish. Most fish have skeletons made of bone. Sharks have skeletons made of cartilage — the same flexible material that makes your ears and the tip of your nose bendy. This makes sharks lighter and helps them swim more efficiently.

One of the most impressive things about sharks is their teeth. Sharks do not just have one row of teeth — they have several rows, one behind the other. When a tooth at the front falls out, a new one from the next row moves forward to replace it. During their lifetime, a shark may grow and lose more than 30,000 teeth. If only human teeth worked the same way!

Many people are very afraid of sharks. Films like "Jaws" — made in 1975 — showed a great white shark attacking and killing people, and it made millions of people scared to swim in the sea. But is this fear based on the truth?

The reality is that shark attacks on humans are extremely rare. According to researchers, about 70 to 80 unprovoked shark attacks happen worldwide every year. On average, fewer than 10 of these are fatal. To put this in perspective, falling coconuts kill more people every year than sharks do. You are also more likely to be struck by lightning than to be killed by a shark.

Most shark attacks are cases of mistaken identity. A shark in the water cannot see very well from below. A person lying on a surfboard with their arms paddling looks very similar to a sea turtle or a seal — which are animals that sharks do eat. When a shark bites a person, it usually lets go quickly when it realises its mistake. This is why most shark attack survivors have one bite wound rather than many.

Great white sharks, tiger sharks, and bull sharks are responsible for most attacks. But even these sharks do not actively hunt humans. Humans are not part of a shark's natural diet. We do not have enough fat on our bodies to be a good meal for a shark — sharks much prefer seals and fish.

Interestingly, humans are far more dangerous to sharks than sharks are to humans. People kill an estimated 100 million sharks every year, mainly for their fins, which are used in shark fin soup.

Sharks have some extraordinary abilities that make them incredible hunters and survivors. Understanding these abilities helps us appreciate just how perfectly designed for ocean life they are.

The most famous ability is the shark's sense of smell. Sharks can detect blood in the water from up to one kilometre away. They can smell one drop of blood in an Olympic-sized swimming pool. This incredible sense of smell helps them find food over huge distances in the ocean.

Sharks also have a special sense that humans do not have at all. They can detect tiny electrical signals produced by the muscles and heart of other animals. These electrical sensors, called the ampullae of Lorenzini, are found in small holes around a shark's nose and mouth. This means a shark can find a fish hiding under the sand on the ocean floor, because the fish's heartbeat produces a tiny electrical signal that the shark can feel.

Another amazing ability is a shark's lateral line — a row of sensors running along each side of its body. This system detects tiny movements and vibrations in the water. It is a little like a sixth sense that tells the shark about everything moving around it.

Great white sharks can also maintain a body temperature slightly warmer than the water around them. This helps their muscles work faster and makes them more powerful hunters in cold water. Most fish are cold-blooded, meaning their body temperature matches the water — so this gives the great white shark a real advantage.

Sharks also heal incredibly quickly. Scientists have observed that some shark species can recover from serious injuries in just a few weeks.

Sharks have been swimming in our oceans for hundreds of millions of years, but today many species of shark are in serious danger. Scientists believe that around one third of all shark species are now threatened with extinction. This means they could disappear from our planet forever — and that would be a disaster for the entire ocean.

Sharks are what scientists call apex predators. This means they are at the very top of the ocean food chain. They eat sick, weak, and old fish and sea animals, which keeps populations healthy. Without sharks, some fish species would grow too numerous and eat too many smaller creatures, which would then upset the entire ecosystem. Healthy oceans need sharks in the same way that healthy forests need wolves and lions.

The biggest threat to sharks is overfishing. Millions of sharks are caught every year, often just for their fins. Shark fin soup is considered a luxury dish in some countries, particularly in parts of Asia. The fins are cut off the shark while it is still alive, and then the shark is thrown back into the water to die. This practice — called shark finning — is now illegal in many countries, but it still continues in parts of the world.

Sharks are also caught accidentally in fishing nets set for other fish. This is called bycatch. Climate change is another growing threat, as warming oceans affect the fish that sharks depend on for food.

The good news is that many people around the world are working to protect sharks. Some countries have made it illegal to fish for sharks in their waters. Scientists are tagging sharks with electronic trackers to learn more about where they travel and what they need to survive. And slowly, public attitudes are changing — as people learn the truth about sharks, more and more people want to protect them.