Complete a dichotomous key for the 10 leaves on the common leaves sheet

A dichotomous key might be considered a significantly useful tool to classify organisms. The key provides an easy and fast way for identification by describing different morphological traits, leading you to the correct taxonomic classification.

When you have an organism -or part of it-, and you need to identify it taxonomically, you use a dichotomous key. The key provides morphological descriptions about different taxonomic groups in an easy way to identify these traits in your individual.

It is simple to read a dichotomous key. The term dichotomous refers to how information is provided. You will always have two options (a and b, or 1 and 2), and you will have to choose one of them according to the characteristics of your organism. The key describes specific morphological traits of organisms that are useful for differentiation.

Probably you might need an atlas or a dictionary to understand some of the technical terminologies. You will also need to carefully observe your specimen, to get to distinguish different traits. If the specimen is too small you might need a loup.

Let us analyze simple example using a group of 5 organisms. Let us assume that you do not know their names, and you need to know what is the individual in the red circle (You will find it in the attached files).

Dichotomous key

Statement 1a ----------- The organism is a vertebrate ----------- Frog

Statement 1b------------ The organism is invertebrate ----------- Go to 2

Statement 2a ---------- The organism has a multisegmented

                                    and elongated body, with too many  ----- centipede

                                    legs.

Statement 2b ---------- The organism has a relatively short body

                                    and with fewer legs ------------------------------ Go to 3

Statement 3a ----------- The organism has 8 legs ----------------------- Spider

Statement 3b ----------- The organism has 6 legs ----------------------- Ant

As you can see, this a very simple example, but ilustrates how the key provides enough information for you to reah the correct option.

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