Why Dolphins Look Like Sharks?

What Finches, Sharks, and Octopuses Teach Us About Survival

Bees and scorpions both have stingers. Bats and birds both have wings. But did you know a bat's wings are more like a human hand than a bird's wing? Strange, right?

Evolution works in surprising ways. Sometimes unrelated species end up looking alike because of similar challenges like bats and birds flying. Other times, species from the same ancestors become completely different, like whales and wolves.

These fascinating processes, known as convergent and divergent evolution, show how life finds its way in a changing world.

Understanding Evolutionary Patterns

Evolution isn't just about survival of the fittest—it's also about adaptation in fascinating ways. Two patterns often stand out when we look at how species evolve: convergent evolution and divergent evolution. These reveal how life finds solutions to survive in a changing world.

Convergent Evolution: Similar Solutions, Different Histories

Convergent evolution happens when unrelated species develop similar traits because they face similar challenges or environments.

Take wings, for example. Bats, birds, and insects all fly, but their wings evolved independently. Bats are mammals, birds are descendants of dinosaurs, and insects belong to a completely different group. Yet, all three found their own way to conquer the skies.

Or think of dolphins and sharks. Dolphins are mammals, and sharks are fish, but both have sleek, torpedo-shaped bodies. Why? Because that shape is perfect for slicing through water efficiently.

Even on a microscopic level, convergent evolution is present. The spike protein of the SARS-CoV-2 virus, for instance, shows similar adaptations across variants to help it infect hosts despite different origins. Nature finds what works and sticks with it.

Unrelated species often develop strikingly similar traits, not because they’re related, but because they face similar challenges. Here are some of the most fascinating examples.

The Perfect Swimmers: Sharks, Dolphins, and Ichthyosaurs

Look at a shark, a dolphin, and an ichthyosaur lined up side by side. At first glance, they look surprisingly alike—sleek, teardrop-shaped bodies built for speed. But their evolutionary stories couldn’t be more different. Sharks are fish, dolphins are mammals, and ichthyosaurs were marine reptiles that went extinct millions of years ago.

Despite these differences, all three developed the same streamlined shape to solve the same problem: how to move through water quickly and efficiently. It’s a classic example of convergent evolution, driven by the demands of aquatic life.

Eyes That See the Same Way: Mammals, Octopuses, and Squids

Camera-type eyes are another brilliant example. Mammals, octopuses, and squids aren’t closely related, but they’ve all developed eyes with lenses, retinas, and optic nerves. These similarities didn’t come from a shared ancestor—they evolved independently. Why? Because these components are the best solution for clear, detailed vision in their environments.

Octopus eye doesn’t have a blind spot!! We have a blind spot where optic nerve connects to the eye and retina is absent. Image taken from here.

Even more fascinating, scientists have discovered shared genetic markers that guide the development of these eyes, highlighting how similar environmental needs can lead to similar biological solutions.

Echolocation in Whales and Bats

What is the similarity between whale navigating the deep ocean and a bat darting through the night sky? Both rely on echolocation—using sound waves to “see” in the dark. Despite their vastly different habitats, whales and bats have developed this ability independently. The most surprising part? They share genetic mutations, particularly in a protein called prestin, that enhance their hearing sensitivity. This is molecular convergence at its finest, showing how similar needs can even shape evolution at the genetic level.