Question: do you know what dichotomous means?

Keywords: ,

  1. I think it just means to divide something into two distinct parts or classifications. Where did you hear the word and in what context dmath56?


  2. Blaire is right.. dichotomy or dichotomous is to split something in to two. so in taxonomy we use dichotomous questions to find the name of an animal. The questions are divided into to groups or types, you follow the yes answers…. for example…

    1a: animal has fins …………………………….. yes go to question 2
    1b: animal has legs…………………………….. if yes go to question 3

    2a: animal has calcium bones ………………. yes – you have a fish
    2b: animal has cartilaginous bones ………… yes – you have a shark

    3a: animal has fur, four legs, dribbles and barks….. yes you have a dog
    3b: animal has fur, four legs, sharp claws and meows …… yes you have a cat

    This is just an example,….


  3. I think Shona sums it up.



  1. i heard it while we where doing a subject on science on dichotomous keys. i want to know in like a dichotomous key.


  2. i get it now so does it basically mean a key that is like cut into parts and then you finally get to the part.


  3. Yes that’s right dmath56.

    Shona’s example is a good one as you can see how you just follow the questions until you find out what species you are looking at. Sometimes these keys can get a little complex. I remember I was trying to identify a species of tick once, which is difficult because they are so small. The dichotomous key asked me to look for some very subtle changes in the shape of the tick’s legs under the microscope (e.g. tick hind leg, third segment has three protrusions – something crazy like that). I’m not a tick specialist so I found it really hard to know if I was looking for the right thing!

    Here’s a pdf that gives you a simple example of a dichotomous key in both written and graphical form –


  4. Awesome explanation


  5. Great Question!


  6. Blaire that website is so awesome and l love that it has all these things like Shona’s example.