Name Date Class

Frog Anatomy

Many of the inside organs in a frog are like those found inside your own body. In both frogs and humans these structures often work the same way. In this activity you will examine the external (outside) parts of the frog. Then, you will dissect the frog carefully to observe the internal (inside) parts.

Strategy

You will observe and compare certain external parts of the frog with similar parts in humans.
You will prepare a table from your observations showing similarities and differences among frogs and humans.
You will identify the internal parts of the frog by matching the frog parts in the diagrams with the actual parts in the animal.

Materials

frog (preserved)
dissecting pan
scissors
dissecting pins
forceps
glue

Visit the Glencoe Science Web site at msscience.com for an alternate activity.

Procedure

  1. Examine the external structure of a frog. To open its mouth, use scissors to cut the sides of the mouth slightly. Look inside. Identify each body part shown in Figure 1.
  2. Compare the frog with a person. Use Table 1 in Data and Observations to record similarities and differences you observe. Also record the functions of each body part.
  3. Place the frog on its dorsal (back) side on the dissecting pan. Pin the legs to the pan.
  4. The frog should now be in a position that will allow you to open its body cavity. Carefully use scissors to cut through the skin and muscle from between the hind legs all the way to the lower jaw. WARNING: Use care when cutting to avoid injury to yourself and others. NOTE: Do not cut too deeply. You do not want to damage the internal structures.
  5. Cut through the bone in the chest region with scissors. Then cut the body wall toward the sides. Fold the tissue to each side and pin it to the dissecting pan. See Figure 2.



  1. Observe the internal organs. Some organs will be hidden from view. Those organs on top must be moved to the side in order to see all parts. NOTE: Female frogs are often filled with eggs. Use forceps to carefully remove the eggs in order to see the organs. Study Figure 3 to help you identify the internal organs. Use the forceps to lift and move the organs.
  2. With scissors, cut out each of the paper organs and glue them onto the frog outline, Figure 2, in the position you found in your frog. Remember to glue first those organs that are found underneath other organs.
  3. When you are finished constructing the paper frog, label each of the body parts.

Data and Observations

Table 1

Frog Structure
Frog Part Similarities and Differences Between Frogs and Humans Function
1. Nostril (outside)

2. Nostril (inside)

3. Teeth

4. Eye

5. Ear

6. Tongue

7. Eustacian tube

8. Esophagus

9. Glottis



Questions and Conclusions

  1. Frogs are insect eaters. Compare the frog tongue and its attachment on the lower jaw to the human tongue and its attachment. How is the frog tongue well adapted for the type of food it eats?



  2. Describe the function of the following organs: (Use your textbook or other references.)
    1. stomach



    2. pancreas



    3. gallbladder



    4. liver



    5. lungs



    6. small and large intestines


Strategy Check

_____ Did you observe and compare the external parts of a frog with the similar parts in humans?

_____ Did you identify the internal parts of a frog?