Chapter 26 Reptiles

Chapter 26 Reptiles Examining Adaptations in Lizards

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Introduction Reptiles are ectothermic, or cold-blooded, vertebrates that are covered with dry scaly skin. They are adapted for reproduction on land. Most species are land dwelling, but some species spend much time in water. Turtles, snakes, lizards, crocodiles, and alligators are reptiles. Reptilian skin is dry, thick, and waterproof, protecting the body from drying out even in very dry climates. The skin is covered by tough scales that protect the animal from injury.

The anole, or American chameleon, is a common lizard found throughout the southern United States. It can be found on shrubs, trees, and fences, and on the ground. Often it is found around homes, and it seems to thrive in areas inhabited by humans. The anole is best known for the ability of its skin color to change from green to brown or gray. This change in skin color is thought to be stimulated by changes in light intensity, temperature, and emotional state. In this investigation, you will observe the external structures of an anole. You will also design an experiment to observe its response to environmental change.

Problem What are the external structures of a lizard? What changes occur in a lizard’s coloration in different environments?

Pre-Lab Questions: Read the entire investigation. Then, work with your lab group to answer the following questions on your lab paper. 1.Anoles are found in dry environments. What type of skin would you predict anoles to have? 2.What evidence would indicate that anoles are land-dwelling rather than water-dwelling animals? 3.What is the difference between Part A and Part B of this investigation? 4.What kinds of things are easier to examine in a preserved anole than in a live animal? What can you learn from the live animal that you can’t learn from the preserved specimen? 5. What is the purpose of averaging the measurements and calculations you will make in Step 2 of Part A of the investigation? Suggested Materials (per group) plastic gloves metric ruler preserved anole dissecting tray live anole paper towels 6 sheets of construction paper (green, yellow, brown, red, black, and white)

Safety Put on safety goggles, plastic gloves, and a laboratory apron. Always use special caution when working with laboratory chemicals, as they may irritate the skin or cause staining of the skin or clothing. Never touch or taste any chemical unless instructed to do so. Follow your teacher’s instructions for storing or disposing of the preserved anoles. Follow your teacher’s directions and all appropriate safety procedures when handling live animals. Part A. External Anatomy of the Anole 1. Feel free to put on safety goggles, plastic gloves, and a laboratory apron. Obtain a preserved anole. Rinse the anole with water to remove excess preservative. CAUTION: The preservative used on the anole can irritate your skin. Avoid touching your eyes while working with the anole. Dry the anole with paper towels and place it on a dissecting tray.

2. Measure the entire body length of the anole in centimeters. Record this measurement in Data Table 1. Also measure the length of the tail alone in centimeters. Record this measurement in Data Table 1. Obtain the measurements of other groups of students and record this information in Data Table 1. Determine the average length of the five anoles and their tails and record this information in Data Table 1. Data Table 1: Copy onto your paper Anole Entire Body Tail Length Only Length (cm) (cm) 1 2 3 4 5 6 Average

3. Observe the texture and color of the anole’s skin. Answer questions 1 and 2 in Analysis and Conclusions.

4. Identify the sex of your anole. Males are generally larger than females and have a dewlap, or fold of skin under the neck. Females have only a small, primitive dewlap. Answer question 3 in Analysis and Conclusions.

5. Locate the head, trunk, and tail of the anole.

6. Examine the head of the anole. Look for the presence of eyelids and external ear openings. Look for the presence of nostrils.

7. Open the mouth of the anole. Look for the presence of teeth.

8. Examine the feet of the anole.

9. In Figure 1 label the following external structures of the anole: head, trunk, tail, dewlap, foot, nostrils, and external ear opening. QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.

Figure 1 : External Anatomy of the Anole 10. Follow your teacher’s instructions for disposing of the anole or storing it for further use.

Part B. Your Own Experiment 1.Formulating Hypotheses: Does an anole change color to adapt to changes in its environment? Record your hypothesis in the space provided.

2.Designing Experiments: Obtain a live anole. Design an experiment to investigate how an anole responds to changes in the color of its environment. Outline the steps in your procedure in the space provided.

3.Obtain your teacher’s approval for your experimental procedure. Then carry out the experiment.

4. Complete a Lab Write up with these Steps: Hypothesis: Independent Variable: Dependent Variable: Controlled Variables: Material: Procedure: Observations: Copy and Use Data Table 2 (Test at least 5 different background colors) Conclusion: What did you conclude? Was your hypothesis correct?

Data Table 2: Copy onto your Paper Background Color Original Color of Anole Anole Color After Several Minutes

Analysis and Conclusions: Answer on your Paper 1. Observing: Describe the texture and appearance of the anole’s skin. 2. Observing: What is the color of your anole? 3. Inferring: What is the sex of your anole? How can you tell? 4. Analyzing Data: How does the anole’s average tail length compare to its average body length? 5. Formulating Hypotheses: What is the possible function of the dewlap? 6. Inferring: What is the function of the eyelids on the anole? 7. Inferring: What is the function of the teeth of the anole? 8. Inferring: How are the anole’s feet adapted for life on land? 9. Analyzing Data: Review your hypothesis and the observations you recorded in Data Table 2. Use your observations to confirm or reject your hypothesis. 10. Inferring: The anole has the ability to lose its tail and then regenerate a new one. How is this a useful adaptation for the anole? 11. Observing: Name three adaptations that anoles have for living on land.