Karthikeyan

What is a dichotomous key?

• A dichotomous key is a tool used to identify organisms.

• It works by giving two opposite choices at each step.

• The word dichotomous means “two branches.”

• By choosing the correct option each time, you can find the correct group or class of an organism.

How does a dichotomous key work?

• You start with general features.

• Then you move step by step to more specific features.

• Each choice sends you to another step or gives you the final answer.

Understanding the given vertebrate key

Step 1:

• Cold-blooded → go to Step 2

• Warm-blooded → go to Step 4

Step 2:

• Has fins but no limbs → Fish

• Has four limbs → go to Step 3

Step 3:

• Has no scales → Amphibian

• Has scales → Reptile

Step 4:

• Has feathers → Bird

• Has fur → Mammal