11 Adaptations-High

Adaptations Written by Ron Fridell

Introduction Afternoon sunlight filters through the trees in a city park. A small bird called a warbler sits on a high tree branch, singing a beautiful song. Suddenly, he stops and dives to catch an insect out of midair. The insect struggles, but it can't escape. The warbler returns to his perch to enjoy his snack. Down on the ground, a bright red cardinal cracks open seeds with his hard bill. A quick, hard rat-tat-tat-tat sound splits the air, and splinters fly as a woodpecker drives her hard, chisel-like beak into a tree. On the hunt for grubs, she drills through the bark as a jackhammer breaks up concrete. On a pond nearby, some ducks float along lazily. Their heads dip down into the water and back up, their wide bills dripping with water.

These birds are all looking for a meal, but what they eat is different. Because their food is different, their beaks have different shapes. The warbler's beak— thin and pointed, like tweezers— is designed for grabbing insects. The cardinal's short, hard beak is made for cracking seeds. The woodpecker uses its long, strong beak to bore into wood, where insects lay their eggs. Ducks have wide bills for straining plants and small fish out of the water. Over hundreds of thousands of years, these birds' beaks changed to help them gather the food they need to survive. All plant and animal species have adaptations— changes that help them survive in their habitat. Why do certain adaptations develop, and how do they help each plant or animal? Let's find out.

Survival of the Fittest Species adapt to changes in their environment in order to survive. How do adaptations develop? Individual organisms within a species are born with differences called mutations. These mutations may change the way an animal or plant grows and how it behaves. Some individuals have beneficial traits and behaviors to help them live in a certain environment. These individuals are able to survive and reproduce. Then those traits and behaviors are passed on to the next generation. Individuals that do not have the beneficial traits and behaviors may not survive. Therefore, they may not reproduce. Over many generations, more and more organisms are born with the beneficial traits and behaviors. These changes become adaptations for the whole species. This notion of species adapting to survive is known as natural selection, or survival of the fittest. The person who first brought this theory to the world's attention was Charles Darwin, a British naturalist. He wrote about it in his book On the Origin of Species by Means of Natural Selection, which was published in 1859.

Let's consider an example of one adaptation and how it developed. Millions of years ago, all whales had teeth and breathed out of holes at the end of their snouts. Over many generations, some whales developed a breathing hole farther up their head. These whales could breathe more easily in deep water. They could rise to the water's surface and take a breath without sticking their snouts above the water. As whales began to spend more time far out in the ocean, away from shore, more whales with higher breathing holes survived. Their babies also had breathing holes high on their heads. The high breathing hole became a characteristic of, or feature that identifies a whale.

Today a whale's nose, called a blowhole, is atop its head. The blowhole makes it much easier for the whale to breathe. When a whale arches its body, its blowhole breaks the water's surface briefly to allow the whale to take a breath. Then, with its lungs filled with a fresh supply of air, it flexes its tail and returns to the ocean's depths.