ID Keys:

Lizards & Snakes

How to key


Lizards & Snakes


Cortland Herpetology Connection

How to use the identification keys

The usefulness of the Amphibian and Reptile Atlas depends on its accuracy. It is essential that each animal you report is accurately identified. But that's not too hard using the identification keys we provide.

These keys are called dichotomous keys. At each step of the key you compare two descriptions to see which best fits the animal you are identifying. Then you go on to another choice until you've identified the animal.

For example, suppose you are holding some kind of reptile or amphibian from New York and wanted to classify it in the correct group (frogs, salamanders, snakes and lizards, or turtles). You could use the following key. Start at Step 1, below.

1.a. Has external gills salamanders
1.b. No external gills 2

This step means that if your animal has external gills (line 1.a.), then it must be a salamander, and you now know in which of the groups your animal belongs. If you click on the linked text "salamander," your browser will take you to the detailed key to salamanders. If your animal lacks external gills (line 1.b.), then go to Step 2. If you click on the 2, you'll jump down to the next step in the key.

2.a. Has scaly skin or a shell 3
2.b. Has neither scaly skin nor a shell 4

In other words, if it has scales or a shell go to Step 3. If not, jump to Step 4.

3.a. Has a shell turtles
3.b. No shell present lizards and snakes

Again, clicking on turtle will take you to the turtle key, and clicking on lizards and snakes will take you to the lizard and snake key.

4.a. Has a tail as an adult salamanders (and newts)
4.b. No tail as an adult frogs (and toads)

When you go to the key for each major group (frogs, salamanders, turtles, or lizards and snakes) you should start with the key to the families at the top of the page. This will tell you the name of the family in which your animal belongs.

Then you'll jump down the page by clicking on the family name to the key for the members of that family to determine the correct name for the species you are identifying. In the species keys, we provide common and scientific names. Click on the name and see a picture of the animal. (If the name isn't linked, that means we don't have a picture of that species yet.)

Some of the terms used in the keys that might be unfamiliar to you are linked to definitions in the glossary. For example in the salamander key you'll find:

3.a. Costal grooves present 4
3.b. No costal grooves Salamandridae

Clicking on costal grooves will take you to that entry in the glossary. Use the back button on your browser to return to the key. Most browsers will return you to the exact spot in the key where you were. With others you may find yourself dropped off somewhere else in the key.

Take your time when using the keys to get a correct identification. If you don't understand a particular term or can't tell if your animal has this trait, check the definitions we provide, look in the books we've sent, or email duceyp@cortland.edu with your question.

Remember the accuracy of the Atlas depends on you making the correct identification.


Dr. Peter Ducey, Project Director
Biology Department, SUNY Cortland
Email: duceyp@cortland.edu
Craig Cramer, Webmaster
Email: cdcramer@clarityconnect.com

Special thanks to all those who generously loaned images and other help. See our credits page for more information.