Purpose: To learn the parts of the frog mouth and the functions of each part. To compare the mouth of the frog with the human mouth.

Procedure: Open the mouth by cutting, with the scissors, directly back through the angle of the jaw on each side. Extend the cut posteriorly to a point slightly posterior to the tympanic membrane. Pull the floor of the mouth ventrally, exposing the mouth cavity. Locate all the parts in bold print from the data section below.

Data: Mouth Cavity

A large tongue lies on the floor of the mouth cavity. It is attached anteriorly in such a way that its forked posterior end can quickly be flicked out of the mouth toward an insect or other small animal upon which it feeds. A sticky secretion is produced by glands in the mouth and coats the tongue so prey sticks to the tongue and is pulled back into the mouth.

The frog has two sets of teeth found on the upper jaw. Locate the maxillary teeth around the edge of the jaw. Two patches of vomerine teeth are found on the roof of the mouth cavity. The teeth of the frog help hold prey, which is swallowed whole. The lower jaw has no teeth.

Paired nasal passages open into the roof of the mouth and are known as internal nares. These are located lateral to the vomerine teeth. Air enters the lungs by way of the glottis, a short longitudinal slit in the floor of the pharynx. Above the glottis is the opening to the esophagus. The esophagus leads to the stomach.

Find the eustachian tubes at the posterior corners of the upper jaw. Probe with your dissecting probe to see where they lead. These tubes equilize pressure within the ear.
The soft palate on the roof of the mouth is known as the floor of the orbit. This is the area of the mouth directly under the eyes.
If your specimen is a male, look for openings of the paired vocal sacs. These are found on each side of the mouth floor slightly medial to the cut angle of the jaw.

Look at the picture of the human mouth below. What parts do frogs and humans have in common? Compare and contrast the similar parts and functions. What parts differ? Explain the differences.

Analysis Questions:

1. Why is the point of attachment of the frog tongue considered an advantageous adaptation?
2. Does the frog chew its food with the vomerine teeth? Explain.
3. Which structures provide evidence that the frog has a partially aquatic life? Explain.

Conclusion: What did you learn about the frog mouth by doing this dissection? What special features does the frog mouth have that make it uniquely adapted to it's environment? Of what adaptive value is each of these structures to the frog? How does the frog mouth compare to the human mouth.