Question

Can more than one dichotomous key be developed to identify the same group of organisms? Explain. To answer this question, refer to this lesson’s dichotomous key for birds.

Answer 1

Certainly. Every organism has a variety of different characteristics. One person writing a key might choose to use different characteristics than another person would use.

For example: Here's a key for separating fish, snake, frog and mouse

1.
A. Has scales on its skin ... 2
B. Has no scales on its skin ... 3

2.
A. Breathes with gills - fish
B. Breathes with lungs - snake

3.
A. Has hair or fur - mouse
B. Has no hair or fur - frog

Here's a different key for the same four animals:

1.
A. Has four legs ... 2
B. Does not have 4 legs ... 3

2.
A. is warm-blooded - mouse
B. is cold-blooded - frog

3.
A. has fins - fish
B. has no fins - snake