Biology Lab assignment/Salamander Dichotomous Key

A dichotomous key is a way to identify an organism using a chart based on paired statements. These keys are organized with statements that begin general and end specific. Please complete the attached lab by putting your answers in the document. Be sure to answer the pre-lab questions, fill in the chart, and answer the post-lab questions. Use the scale on the Figure rather than using a ruler for any measurements. If you are unsure about the descrptions in the dichotomous key, please ask for clarification. Salamander Dichotomous Key Suppose you find a large colorful salamander while walking near a pond. Chances are the salamander has already been named and classified, but how can you learn its identity? As an aid to help others identify unknown organisms, biologists have developed classification keys. These classification keys are often called dichotomous keys (the word dichotomous comes from the word dichotomy meaning “two opposite categories”). A dichotomous key presents the user with two opposite statements about some trait of an organism. By choosing one of the two statements that best describes the unknown organism, the user is lead to further pairs of statements. By going from one set of statements to another, the name of the organism or its classification group is determined. Pre-lab questions: 1. How many choices does a dichotomous key provide at each step? 2. What are some of the differences you see among the salamanders illustrated? Procedure: It will be easiest to complete this assignment if you print out the attached pages so you can look at both at the same time. Use the dichotomous key provided on page 2 to identify the species of salamander shown in Figure 1 on page 3. Begin by looking at a picture of one salamander and read statements 1a and 1b. One of the statements describes the salamander; the other statement does not. Follow the directions for the statement that applies to that salamander and continue following the correct statements until you have identified it. Record the scientific and common names of the salamander in the data table below. Repeat step 2 for each of the other salamanders in Figure 1, always starting with statements 1a and 1b and working your way to the answer. Each name will be used only once (one picture per name). Data table: Salamander Scientific Name Common Name 1 2 3 4 5 6 7 8 9 10 11 Post-lab questions: Answer the following using complete thoughts. 3. As you used the classification key to identify the salamanders, did the characteristics you used start out general and become more specific, or did you start with specific characteristics that became more general? 4. What two names make up the scientific name of each salamander?