Interesting facts about sharks

Sharks have been in existence on earth for millions of years, even before dinosaurs. Possibly the most significant extinct ancestor of modern-day shark was the megalodon. It was about 20 meters long and weighed up to 48 tons.

Out of the over 500 species of sharks, only 3 are responsible for a majority of the reported human attacks. These three are the bull shark, great white shark, and the tiger shark. But such attacks are also quite occasional. In fact, for each human a shark kills, there are two million sharks killed by humans worldwide. This has led to a massive reduction in the world’s population of sharks putting them on the brink of extinction. More so, there is 75% probability of humans to be killed more by lightening than sharks.

Sharks never stop growing teeth. They get up to 30,000 teeth during their lifetime. Shark teeth grow from the back and move forward when required, thus for every tooth that is broken in front, there is a row behind to replace it at all times.

There are a few species of sharks that possess the ability to move into freshwater and not stay restricted to saltwater systems only. In places like South Africa, the Bahamas, and Australia, bull sharks move up and down rivers. This movement consumes a lot of their energy but also gives them a new batch of prey too. Meanwhile, around the coral reefs in Australia and New Guinea lives the epaulette shark. This shark has the capacity to climb out of water in low tide and ‘walk’ between pools to hunt for prey that has been stranded.

Talking about size, this great predator can grow up to an astounding 6.1 in length and weigh more than 2000 kg. The females typically grow larger than the males.

Sharks have great eyesight. They see in color and have the ability to see clearly whether it’s day or night. Sharks, although, do not have eyelids so they have to roll their eyes to the back of their heads to protect them.

While humans have only five senses, the great white shark possesses six. This sixth sense is used to detect a natural stimulus and notify the sharks of the objects around them. Sharks are able to find prey easily because this special sense allows them to detect signals of the electric field transmitted by all animals.

In addition, the great white sharks have the most potent sense of smell of all sharks and can perceive the littlest drop of blood in a million parts water. They are also quite specific about what they will or will not eat than other sharks. This is due to the taste buds located in their throat and mouth.

Brief Shark History

For close to 450 million years now, sharks have been swimming in the oceans. But sharks are not only known for their prolonged existence. They are also known as the perfect predators. They have, over the many years of evolution, developed many astonishing abilities.

Life is said to have come into being on earth about 3.8 billion years ago. Life started on earth as bacteria and did not develop beyond the one-celled stage until about 580 million years ago. The very first fish surfaced about 510 million years ago. These fishes were called ‘Ostracoderms’. They were jawless fishes with armour. After these fishes then came the sharks. Although there is a little disagreement between paleontologists as to when exactly they came into being, whether 455 0r 425 million years ago.

A lot of people assume that dinosaurs dominated the ancient world. This isn’t quite accurate because dinosaurs did not surface until around 230 million years ago. Around the same time that mammals came into being. Although modern humans only date back roughly 60,000 years ago, the first animal that was human-like, also known as a hominid, dates as far back as about 4.5 million years ago. More so, documented civilization has lasted just about 5,000 years. All these indicate that sharks have existed almost 100 times longer than the first human-like animals and about 3 times longer than dinosaurs (or say twice as long as dinosaurs in birds are included).

The oldest shark fossils

The oldest fossilized proof of ancient sharks come from shark-like scales that date back to the Ordovician period (about 455 million years ago). Although some paleontologists argue that these scales are not sufficient enough to be called shark-like scales, there is no argument that the scales found dating back to the Silurian Period (about 420 million years ago) are from sharks. The shark scales from this period were found in Mongolia and Siberia. The most far dated shark teeth are from the Devonian Period, around 400 million years ago, and they were found in Europe. Other than these scales and teeth, nothing else has been found to tell us more about those early sharks.

A complete shark fossil found remain dated to around 380 million years old. This includes a fossilized shark braincase found in Australia, most likely a Xenacanth. Remains of this species or similar species have also been found in Saudi Arabia and Antarctica.

Sharks have survived all five mass extinctions

There are numerous proofs, throughout history, of disastrous events that considerably changed the environment, resulting in the mass extinction of a large percentage of species. In the most brutal of such events, about 251 million years ago, as much as 95% of species on earth were wiped out, possibly due to either volcanic activity or a comet impact. Over the past 439 million years, five major mass extinction events have taken place.

For species that survived, this destruction presented an opportunity to thrive and prosper if previous predators were killed or new, uninhabited territories opened up. These, therefore, have often given rise to ‘adaptive radiations’ or a significant rise in new diverse species. Sharks, due to their adaptable design, have survived all of these five mass extinctions. They have also gained from some adaptive radiations resulting in the appearance of many new interesting sharks.