How to use a Dichotomous Key

One of my guilty pleasures is taking personality quizzes online with silly titles like, “Which Flavor of Ice Cream are you?” or “Which Teen Heartthrob is Your One True Bae?”. They ask questions like “Do you like long walks on the beach?” and you answer “yes” or “no” before it leads you to a new question, ultimately ending (you hope) by telling that yes, indeed, Zayn Malik is your One True Bae! These quizzes, though often frivolous, are utilizing a very scientific process to lead you to an answer. This tool is called a Dichotomous Key.

A Dichotomous Key is a tool used to categorize living organisms based off their characteristics using simple yes / no questions. The process of using a dichotomous key is simple; begin by observing the whole organism you want to identify. The key will ask questions that lead to alternate possibilities or end in your desired identification. Let’s walk through our example below!

1. Choose an animal you want to identify
2. Does this animal have a backbone?
   1. If NO – Octopus
   2. If YES – continue
3. Is the animal a fish?
   1. If NO – Catalina Island Fox
   2. If YES – continue
4. Does the fish use camouflage to blend in?
   1. If NO – continue
   2. If YES – Giant Kelpfish
5. Is the fish pink?
   1. If NO – Juvenile Garibaldi
   2. If YES – Juvenile California Sheepshead

-Max Veenema wrote this How to.