Types of Animals on Earth

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Earth is the only known planet up to date which sustains life. A few millions years ago, Earth was home to the one of the most vicious and devastating creatures well-known to mankind ̶ dinosaur. Wrapped in a cocoon of evolution, Earth, along with most living beings, had endured metamorphosis, transforming the world to what it is now. Gigantic deadly dinosaurs went extinct, whilst only a minority that survived mutated into smaller-sized animals. Animals that roam the Earth are classified into three major categories, namely mammals, reptiles and amphibians, where each category is further divided into their respective orders (refer to Figure 1 in Appendix 1).

The first major type of animal is mammal. There are more than 4,000 different species of mammals. The smallest is the hog-nosed bat, which weighs 0.05 ounces. The largest is the blue whale, which can be 100 feet long and weigh 150 tons. But whether they live on land or water, all mammals share some common characteristics. All mammals are vertebrates. They have either a backbone or a spine. Besides, all mammals are endothermic, also known as “warm-blooded”. They regulate their own body temperature which allows them to live in almost every climate on Earth. Mammals have hair or fur on their bodies. Furthermore, they produce milk to feed their babies. This allows them to spend more time with their young and teach them important skills they need to survive on their own.

As Peterson (2006) mentioned, the word mammal is derived from the milk-producing mammary glands that are unique to the class Mammalia. Mammals owe their spectacular success to many features. Many of the most important and most diagnostic mammalian characteristic serve to further intelligence and sensory ability, t...

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...alliday, 2002). Caecilian is a type of Gymnophionan.

Works Cited

Vaughan, T. A. (1986). Mammalogy. New York, NY: Saunders College Publishing.
Eisenberg, J. F. (1999). Mammals of the neotropics (volume 3): the central neotropics: Ecuador, Peru, Bolivia, Brazil. New York, NY: University Of Chicago
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O’Shea, M. & Halliday, T. (2001). Reptiles and amphibians. New York, NY: DK
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Ballinger, R. E. & Lynch, J. D. (1983). How to know the amphibians and reptiles.
New York, NY: Wm. C. Brown Company Publishers Dubuque, lowa.
Tyning, T. F. (1990). A guide to amphibians and reptiles. New York, NY: LB, Little,
Brown and Company
Cook, F. R. (2007). Amphibians. Retrieved from www.thecanadianencyclopedia.ca/en/article/amphibian Peterson, R. L. (2006). Mammal. Retrieved from
http://www.thecanadianencyclopedia.ca/en/article/mammal/

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