They have been here for more than 400 million years. They have evolved. They have survived. Now, Sharks are at risk of extinction at the hands of the human species, with their populations declining at an alarming rate- some species down by 90%.
The History
Sharks have existed substantially longer than people. There are suggestions of evidence dating back 450 million years, from the Ordovician Period. Certain paleontologists believe that those first discoveries were of another species and that the first shark fossils originated in the Silurian Period- 420 million years ago.
During that time, the physical appearance of sharks differed greatly. They did not take on their modern appearance until about 100 million years.
The Evolution
Sharks have had plenty of time to evolve, fine-tuning everything from their appearance to their organ functions. There are approximately 500 known species; at their smallest, dwarf lantern sharks are only a few inches long and at their largest, whale sharks have been known to be 40 feet long. Despite their size, they are known as gentle giants and do not seem bothered when divers swim alongside them.
Species like the bull shark have the unique ability to change the function of their liver to survive in both saltwater and freshwater. Spiny dogfish and whale sharks can live to one hundred years, exceeding the normal lifespan of a shark by 70-80 years.
Shark skeletons are made of cartilage to reduce body density and maximize energy usage. It is possible for sharks to be crushed by their own body weight if they are on land.
The Threat
In Asia, it is believed that sharks can cure cancer and increase social status. There is no scientific evidence whatsoever that proves cancer-curing properties are in sharks, and certain species have even fallen prey to the disease.
The idea that social status holds prevalence over life itself is part of the reason why more than 125 species are currently at risk of extinction. There are several cultures that do not realize the tragic truth about endangered and at risk shark species.
In Japan and Australia, shark fin soup is a common delicacy but many people do not realize that acquiring fins is often done illegally and cruelly.
Fishermen capture live sharks, use hot metal blades to remove the fins, then throw the shark -still alive- back into the ocean. Since sharks need to be constantly moving to breathe, without fins they are either attacked by predators or suffocate in the water. Despite the laws in place, the rising market for fins is responsible for millions of deaths each year.
The Reproduction
From seafood to the cure of cancer, sharks are being killed much, much faster than they can reproduce. The female bull shark does not reach sexual maturity until she is eighteen years old. Frilled sharks sometimes wait three and a half years before giving birth. For species that usually only live twenty to thirty years anyways, people are incredibly threatening.
The Reality
It is estimated that, in total, 100 million sharks are killed every year. Whether it is direct or indirect, humans are undoubtedly the cause. From pollution to fishing, some species' populations have declined by 90% in less than 30 years. Without stronger enforcement of the laws that exist, raising awareness about the severity of this situation, and actively working to protect these magnificent fish, sharks will be extinct in as little as 20 years. The impact of their extinction would have incomprehensibly negative consequences.
