Answer:
Imagine seeing a dolphin, which is an aquatic mammal, walking around on land. While hard to imagine, it's actually where the modern dolphins' ancestors lived long ago. Dolphins began living in the ocean around 50 million years ago and never returned to land. They had arms that evolved into flippers, legs that evolved into a tail, and nostrils that evolved into a blowhole.
Physical Adaptations
The most important dolphin adaptation is the blowhole located on the top of the body. The blowhole allows a dolphin to come up to the surface, easily take in air, and continue swimming. When a dolphin pup, or baby, is born, the mother gives the baby a lift to the surface. Here the dolphin pup gets its first gulp of air.
The dolphin's sleek, elongated body shape allows them to zip through the water with ease. Because dolphins are mammals, they once had hair. They still have hair follicles, or tiny holes, all over their bodies. However, through evolution, they've lost all of their hair to reduce drag when swimming.
Dolphins also have several adaptations that aid them in catching and eating food. To find food, a dolphin uses the process of echolocation, whereby it makes a clicking sound that bounces off of an object and back to the dolphin. This helps a dolphin determine where an object is located. Once a dolphin finds food, it moves very quickly through the water to catch it.
A dolphin can hold its breath for up to 12 minutes, which allows it to dive and hunt when needed. Scientists believe that when a dolphin is asleep, only half of its brain is really sleeping, allowing the other half of the brain to signal that dolphin to surface and take in air even while asleep.
