Rana Catesbeiana (Bullfrog) Essay
I was amazed to find out just how ancient frogs are. For 190 million years, the ancestors of modern frogs have roamed the earth, looking much the same as they do today. This means that at one time when there was a huge dinosaur eating a plant, there could have been some type of frog down by its feet. About 3,800 species of frogs and toads have developed since the dinosaur days. The secret to their success is their amazing adaptability. Frogs have evolved to live in a large variety of climates. They can be found just about anywhere there is fresh water- on all continents except Antarctica. Though they thrive in warm, moist tropical climates, frogs also live in deserts and high on 15,000-foot mountain slopes.
They can be so adaptable because they are cold blooded, which means that their body temperature can change along with the temperature around them. When temperatures drop, some frogs dig burrows underground or in the mud at the bottom of ponds. They hibernate in these burrows until spring, perfectly still and scarcely breathing. A frog’s skin also plays a big role in their survival. It is through their skin that they both drink and breathe. Frogs don't swallow water; they get all the moisture they need through their skin, which must stay moist. If it dries out, oxygen can't pass easily through it and the frog can suffocate. Frog skin secretes mucus that helps keep it moist. Even so, their skin tends to dry out easily, which is why they usually stay near bodies of water. About once a week, frogs shed their skin. The process begins with the frog doing a lot of twisting, bending, and stretching to loosen the old skin. Then the frog pulls the skin over its head like a sweater and usually eats it.
Two other parts of the frog have helped it to survive all these years as well. First, the hind legs of the frog, which enable some frogs to jump twenty times their body length. This would allow them to quickly get away from...
Please join StudyMode to read the full document