Keys and identification

Keys are used to identify different species. A key will usually ask questions based on easily identifiable features of an organism. Dichotomous keys use questions to which there are only two answers. They can be presented as a table of questions, or as a branching tree of questions.

Branching tree example

This tree could help you identify a new vertebrate. For example, if it had no fur or feathers and dry skin, you would follow the right-hand pathway at the first and second junctions, but the left-hand pathway at the third junction. This would lead you to identify the animal as a reptile.

Fur then mammal (ie badger). No fur but feathers then bird (ie owl). No feathers but dry skin, then reptile (tortoise).  Moist skin and scales then fish. Moist skin no scales then amphibian (ie frog).
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