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Animal Classification |
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Since there is a large number of very different living things on Earth, you need a simple classification system. A manageable way to classify animals would be to choose one feature to divide the large group into smaller groups. What is a biological key?In this lesson, you will be looking at how animals were classified in ancient times. That is, you'll be understanding and using a classification system. Biologists have made understanding and using a classification system easier by writing keys. A biological key is like a door key because it unlocks. But a biological key unlocks information, not a room. A biological key unlocks information about a classification system. There are many different types of keys, such as branching keys, dichotomous keys and circular keys. In this lesson, you will be learning how to use biological keys. You will be using a key for Aristotle's classification system. With the key, you can deduce the features that Aristotle used to classify animals. Classifying animals in ancient GreeceAristotle was one of the great thinkers of his time. He lived in the 4th century BCE. One of his many achievements was to outline a scientific classification of animals. He carefully observed many animals to find features that he could use to classify. Red blood was one of the features that Aristotle used. (He also used ways of reproducing and habitats.) For example, Aristotle observed and classified mammals, lizards, birds, fish, insects, shellfish and jellyfish. The diagram below shows how Aristotle grouped these animals.
Biological key for Aristotle's animal classification system This diagram is called a biological key because it classifies living things. It is also a branching key because each group of animals is split into smaller groups, like branches off a tree trunk and twigs off a tree branch. And it is a dichotomous key. Dichotomous comes from a Greek word that means cut into two parts. So this is a dichotomous key because each group is cut into two new groups. Did you wonder why the words in the key become smaller as you move down through the key?
This is a way of reminding you that a key divides the main group at the top of the key into smaller groups.
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Lesson 12 - Animal classification |
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