Sharks: The Elders of the Ocean
Dinosaurs have long fascinated scientists, eager children, and curious adults alike. As relicts of the past, they have captivated our imagination and we have spent considerable effort to learn about their ways. Incredibly, there are descendants of animals living today that existed long before the age of the dinosaurs and continue to swim today. The earliest record we have of a shark fossil is from 420 million years ago (dinosaurs first appeared around 230 million years ago). Sharks have existed long before and even after dinosaurs, and yet we often do not have the same level of admiration for sharks as we do for dinosaurs. Sharks are some of the longest surviving animals on earth, which is why they are sometimes (erringly) referred to as living fossils. The shark lineage has survived asteroids, historic climatic events, mass extinctions, and rising temperatures and sea levels that caused the extinction of many other lineages of plants and animals.
Scientists believe sharks adaptations including niche-radiation, the ability to repair DNA, flexibility in their diet, and electric sensors (called ampullae of Lorenzini) have all contributed to their longevity. Now sharks face their gravest threat – humans. Scientists estimate that 100,000,000 sharks and rays are killed each year by humans. These sharks are actively killed for their fins or other body parts, their meat or are caught and thrown away as by-catch in fishing nets by the tons in the case of rays.
Humans are obsessed with being killed by a shark, stoking unfounded fears that sharks are hunting humans, yet only around 10 humans die a year from shark encounters. It is we who are killing sharks to extinction. Once a prolific open ocean predator, for instance, oceanic whitetip populations (Carcharhinus longimanus) have now declined by up to 95%.
It that would be terrible tragedy if sharks were to go extinct by our hands, after surviving so much for so long. Imagining a world without sharks is both emotionally heartbreaking and ecologically frightening. We need top predators to maintain a healthy ecosystem. Without sharks, the marine world becomes unbalanced. There is much to learn about how sharks have survived for so long. Doctors want to understand how sharks avoid cancer and rapidly heal wounds. Shipbuilders want to mimic sharks engineering to save on fuel and improve navigation. Scientists want to understand sharks’ migration patterns to better predict climate events. There are endless discoveries we would never learn about if we kill sharks to extinction. The full consequences of wiping out sharks are hard to predict, but the bottom line is that it would be disastrous in both ways we already see and ways we cannot yet fathom.
Typically humans revere and respect those who have lived a long time. If we can shift the way we see sharks, perhaps we will care more about protecting them. Sharks are not the mindless killers of the ocean, but rather the knowledgeable and wise grandparents who have lived through many tumultuous times.
Our elders deserve our respect and care.
|Guest contributor, Christina Briegleb is a writer and works in non-profit development In San Francisco California, and is a volunteer on the Shark Stewards team|