The Owners of the Ocean: The True Story of the Sharks

The Silent Predator of the Depths

In the depths of the ocean, where light barely penetrates and life develops in unimaginable ways, lives a being that has captured the imagination and fear of humanity for centuries: the shark. These majestic predators, with their impressive anatomy and hunting skills, represent one of the most fascinating enigmas of the marine world. However, their reputation as "killing machines" is being reconsidered in light of new research.

Anatomy of a Superpredator

Sharks have been around for more than 400 million years, long before dinosaurs walked the Earth. This evolutionary longevity speaks to their efficiency as predators. With more than 500 species, these cartilaginous fish range from the small dwarf lantern shark, which fits in one hand, to the formidable whale shark, which can reach 12 meters in length. Their bodies are designed for speed and agility, with skin covered in dermal denticles that reduce friction with water and powerful musculature that allows them to charge their prey with great force.

True Monsters or Victims of Public Perception?

Despite their ferocious reputation, the reality is that sharks rarely pose a threat to humans. In 2022, fewer than 100 unprovoked attacks were recorded globally, with only a handful of these proving fatal. Contrary to popular belief, sharks do not actively seek out humans as prey. Many of the attacks are cases of misidentification, where sharks mistake swimmers or surfers for seals or fish.

The Real Threat: Extinction

What should concern us most is the alarming decline in shark populations. Overfishing, habitat destruction and poaching for their fins have brought many species to the brink of extinction. Shark fins, coveted for shark fin soup, are especially valuable, prompting a brutal practice called "finning," where sharks' fins are cut off and the rest of the body is returned to the sea, leaving them at a slow and painful death.

Guardians of the Marine Ecosystem

Sharks play a crucial role in the health of the oceans. As top predators, they regulate the populations of other marine species, maintaining the balance of the ecosystem. Its disappearance could trigger a domino effect that would seriously affect marine biodiversity. Scientists have observed that in areas where sharks have been eliminated, populations of their prey are increasing uncontrollably, which in turn negatively affects coral reefs and other marine structures.
The oldest known shark is the Cladoselache, which lived approximately 380 million years ago, during the Devonian period. These primitive sharks are known from their fossils, which have been found primarily in North America.

Characteristics of Cladoselache

Anatomy: Cladoselache was relatively small compared to many modern sharks, measuring around 1.8 meters long. It had a slender body and a heterocercal tail (where the upper lobe is larger than the lower one), similar to that of modern sharks.
Diet: Cladoselache is believed to have been a fast, agile predator that fed on small fish and cephalopods.
Structure: This shark lacked many features found in modern sharks, such as placoid scales. However, it had simple, sharp teeth that were suitable for catching and holding prey.
Importance in the Evolution of Sharks
Cladoselache is important because it represents one of the first examples of sharks exhibiting characteristics that would define this group of cartilaginous fish. Their fossils help scientists understand how sharks evolved and adapted to their environment over hundreds of millions of years.

In evolutionary terms, sharks like the Cladoselache provide a crucial window into ancient marine life and the evolution of aquatic predators, demonstrating the impressive longevity and adaptability of these magnificent animals.
During the Devonian period, approximately 419 to 359 million years ago, Cladoselache played a crucial role in marine ecosystems. This period is often referred to as the "Age of Fish" due to the great diversity and abundance of aquatic life forms. The Cladoselache, as one of the oldest known sharks, had several important functions in its environment:

Role of Cladoselache in the Devonian Ecosystem

1. Top Predator
The Cladoselache was an agile and efficient predator, occupying a high level in the marine food chain. Their diet consisted mainly of small fish and cephalopods. By hunting and controlling the populations of these species, the Cladoselache helped maintain balance in the marine ecosystem, preventing overpopulation of its prey and contributing to the stability of the biological community.

2. Natural Selection
As a predator, Cladoselache also played a role in natural selection. By hunting weaker or diseased prey, it helped ensure that only the strongest and healthiest individuals survived and reproduced. This process of natural selection promoted the evolution of prey species, driving adaptations that improved their survival, such as greater speed, camouflage or escape strategies.

3. Diversification of Ecological Niches
The presence of predators such as Cladoselache stimulated the diversification of ecological niches. Prey developed various strategies to avoid predation, leading to greater biological diversity and the emergence of new species with specific adaptations to escape or defend themselves from sharks.

4. Ecosystem Health Indicator
Cladoselache and other top predators are considered indicators of ecosystem health. Their abundance and well-being reflect the wealth and balance of marine communities. An ecosystem with a healthy population of predators generally indicates a well-structured and functional food chain.

Conclusion: A New Perception

It is imperative that we change our perception of sharks. Instead of fearing them, we should admire their vital role in the ecosystem and take steps to protect them. Shark conservation is not only crucial for the health of the oceans, but also for the well-being of the planet. Through education and conservation, we can ensure that these incredible predators continue to reign in the depths for millions more years.

References
https://www.artefactmagazine.com/2024/02/29/7-things-shark-tale-got-wrong-about-the-ocean/
https://www.surfertoday.com/environment/ocean-ramsey-the-shark-whisperer
https://ocean.si.edu/ocean-life/sharks-rays/great-white-shark
https://www.csiro.au/en/research/animals/marine-life/Sharks/When-sharks-meet-people