Frog Anatomy Lab Activities (PDF)

**Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Score \_\_\_\_\_\_\_\_** **Laboratory Activity No. 6** **ANIMAL CLASSIFICATION** **Objectives:** - To observe and identify the morphological characteristics of a frog and classify it wit...

**Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Score \_\_\_\_\_\_\_\_** **Laboratory Activity No. 6** **ANIMAL CLASSIFICATION** **Objectives:** - To observe and identify the morphological characteristics of a frog and classify it within the Phylum Chordata, Subphylum Vertebrata, and Class Amphibia. **Activity:** 1. Place the frog on the dissection tray with its dorsal side facing up, ensuring the back is fully visible for proper observation and classification 2. Insert one image of a toad and one image of a frog in dorsal view into the designated box provided. Indicate the taxonomic classification of the specimen. A. Toad B. Frog **Frog (Dorsal View)** **Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Score \_\_\_\_\_\_\_\_** **Laboratory Activity No. 7** **THE EXTERNAL ANATOMY OF THE FROG/TOAD** **Objectives:** 1. To familiarize the external anatomy of the frog/toad. 2. To identify the body parts of the medial axial region and the peripheral appendicular region. Materials: - Alive frog/toad - Aquarium half filled with water - Stopwatch The body of an animal has a definite form and is composed of various structural parts. These enable the animal to carry out the activities necessary for life, the physiological processes within the body, and the external relationships with its environment. The Frog is a convenient representative animal for an introductory subject because of its cheap and abundant supply and size. The life cycle can be observed easily, and it shows resemblance in form and structures to higher vertebrates and man. The details of its structures readily demonstrated, and its life habits are easily observed The body of the frog is divided into a *medial axial* region, composed of the *head* and *trunk*, and a peripheral *appendicular* region, composed of the paired *forelimbs* and *hindlimbs*. *Frogs can be recognized from toads very easily. The table below will help you.* --------------------------- ------------------------ ----------------------------- **Bases** **Frogs** **Toads** Texture and color of skin Slimy, darkly colored Rough, warty, light colored Shape of the head Pointed, elongated Blunt, wide Shape of the body Elongated and slim Flat and wide Shape of the tongue Notched at the base Oval and broad Habitat Trees and grassy areas Rocky, stony places --------------------------- ------------------------ ----------------------------- Activities: 1\. Put the specimen on a pan. Secure the frog so that it cannot escape. Notice the way it breaths. 2\. Locate the eyes. Notice that it is protected by three eyelids. It has thick upper and lower eyelids and a thick transparent membrane called *nictitating membrane*. In man, this third eyelid is a vestigial structure called plica semilunaris found as a triangular fold at the inner corner of the eye. Touch the eyeball. Give the action of each eyelid in closing the eye. What is the role of the third membrane when the animal is on land? 3\. Observe the two pairs of appendages. Push the animal from behind to induce it to jump -- relax the strings so they can jump freely. Observe the action of each pair of legs when the animal jumps; lands; hops; rests. What is the correlation between the size of the legs and their functions? 4\. Feel the skin on the dorsal and ventral sides. Note any difference? Why? Examine the coloration. Any variation? Why? Locate the enlarged glands below the tympanic membrane at both sides of the neck. These are the poison glands. What are they for? The tympanic membrane is not necessarily an organ for hearing. What is its special function? 5\. Determine the sex of your specimen -- use a suitable reference. Upon dissection, you will verify if you were right. Why? 6\. Put the specimen in an aquarium half filled with water. Let it swim freely. Notice the action of both legs. Look at the toes and note the webs. Do the webs perform any special function? 7\. Draw and label the dorsal view of a frog/toad showing all the external parts mentioned. 1. **Documentation of Frog pithing and pinning. Make sure you are included in the pictures.** -- -- 2. **Picture of actual frog specimen with a corresponding label of its external anatomical parts.** -- -- DOCUMENTATION REFERENCE Figure 1. External anatomy of the frog **Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Score \_\_\_\_\_\_\_\_** **Activity No. 8** **DISSECTING OF FROG/TOAD** **Objectives:** 1\. To familiarize the procedure in dissecting a frog/toad. 2\. To be able to dissect a frog/toad following correct procedure. **Materials:** - Dissecting pan - Dissecting Set - Live frog/toad - Chloroform and formalin - Preserving bottle **Pithing Procedure:** a. Hold the frog facing away from your body, with the lower extremities extended. b. Grasp the frog with your first two fingers: first finger on the nose, second finger under the jaw. Flex the head forward (away from your body). c. Move probe down midline until you come to the soft spot. Do not use undo pressure on the frog skin. Frog skull is fairly hard cartilage; soft spot is at the end of the skull. d. Insert the probe quickly into the cranial vault and sever the brain and spinal cord. e. Move the probe into the cranial vault and move it from side to side to destroy the brain. You can feel inside the cranial vault, but the frog can't feel anything. Without the brain, perception of any sensory phenomena is impossible. f. Test for reflexes to confirm that sensory perception has been destroyed and ensure that the spinal cord is still intact, although it is now in shock. **Dissection Instructions:** a. Place the frog in the dissecting pan ventral side up. b. Use scissors to lift the abdominal muscles away from the body cavity. Cut along the midline of the body to the forelimbs. c. Make transverse (horizontal) cuts near the arms and legs. d. Life the flaps of the body wall and pin back. \*If your specimen is a female, the body may be filled with eggs. You may need to remove these eggs to view the organs. **Activities:** I. Locate each of the organs below. Check the box to indicate that you found the organs. Fat bodies Heart Small intestine Large intestine ------------ -------------- ----------------- ----------------- Peritoneum Lungs Pancreas Spleen Liver Gall Bladder Stomach Esophagus 1\. Fat Bodies \--Spaghetti shaped structures that have a bright orange or yellow color, if you have a particularly fat frog, these fat bodies may need to be removed to see the other structures. Usually they are located just on the inside of the abdominal wall. 2\. Peritoneum ­ A spider-web like membrane that covers many of the organs, most easily seen covering the heart. 3\. Liver\--The largest structure of the the body cavity. This brown colored organ is composed of three lobes. The right lobe, the left anterior lobe, and the left posterior lobe. The live secretes a digestive juice called bile which is needed for the proper digestion of fats. 4\. Heart - at the top of the liver, the heart is a triangular structure. The left and right atrium can be found at the top of the heart. A single ventricle located at the bottom of the heart. The large vessel extending out from the heart is the conus arteriosis. 5\. Lungs - Locate the two spongy lungs by looking behind the heart and liver. 6\. Gall Bladder \--Lift the lobes of the liver, there will be a small green sac under the liver. This is the gall bladder, which stores bile. (hint: it kind of looks like a booger) 7\. Stomach\--Curving from underneath the liver is the stomach. The stomach is the first major site of chemical digestion. Frogs swallow their meals whole. Follow the stomach to where it turns into the small intestine. The pyloric sphincter valve regulates the exit of digested food from the stomach to the small intestine. 8\. Pancreas - This structure is located on the inside curve of the stomach. It it a gland that often falls apart during the preserving process so it many not be visible on your frog. 9\. Small Intestine\--Leading from the stomach. The first straight portion of the small intestine is called the duodenum, the curled portion is the ileum. The ileum is held together by a membrane called the mesentery. Note the blood vessels running through the mesentery, they will carry absorbed nutrients away from the intestine. Absorption of digested nutrients occurs in the small intestine. 10\. Large Intestine\--As you follow the small intestine down, it will widen into the large intestine. The large intestine leads to the cloaca, which is the last stop before solid wastes, sperm, eggs, and urine exit the frog\'s body. (The word \"cloaca\" means sewer.) The opening to the outside of the doy is the anus. 11\. Spleen\--Return to the folds of the mesentery, this dark red spherical object serves as a holding area for blood. 12\. Esophagus\--Return to the stomach and follow it upward, where it gets smaller is the beginning of the esophagus. The esophagus is the tube that leads from the frogs mouth to the stomach. Open the frogs mouth and find the esophagus, poke your probe into it and see where it leads. II. 1. Ensure to have proper documentation of frog pithing, pinning and dissecting. 2. Always take pictures of your specimen alone and another picture of the specimen with you. 3. Pin the Frog in a dissecting pan. 4. Observe the beating of the heart. Count the number of beats per minute. Get the average of three trials. Compare with your own heartbeats. Describe the heart of the frog/toad as it beats. 5. Expose all the internal organs. Try to identify them. How do the organs of the frog/toad compare with that of man? Describe the organs of the frog/toad. 6. Draw the specimen showing the correct placement of these organs. 7. Put back the specimen in the bottle or beaker. Ask for formalin or ethanol from the teacher to preserve your specimen. **Diagram:** **Observations:** 1\. Frog's Heartbeat 1st trial \_\_\_\_\_\_\_\_\_\_\_\_ 2nd trial \_\_\_\_\_\_\_\_\_\_\_ 3rd trial \_\_\_\_\_\_\_\_\_\_\_\_ Average \_\_\_\_\_\_\_\_\_\_\_ 3.Describe the beating of the heart 4.How do the organs of the frog compare with that of man? **Name \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Date \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Score \_\_\_\_\_\_\_\_** **Activity No. 9** **ANATOMY OF THE FROG'S MOUTH** **Objective:** 1. 1\. To identify and describe the internal structures of the frog\'s mouth, including the tongue, teeth, and openings. 2. To understand the functional adaptations of the frog's mouth anatomy in relation to its feeding habits and ecological role. **Materials:** - Frog - Dissecting pan - Dissecting kit - Scissors - Probe **Procedure**: Pry the frog\'s mouth open and use scissors to cut the angles of the frog\'s jaws open. Cut deeply so that the frog\'s mouth opens wide enough to view the structures inside. 1\. Locate the **tongue**. Play with the tongue. Does it attach to the front or the back of the mouth? \_\_\_\_\_\_\_\_\_\_ (You may remove the tongue). Draw a sketch of the tongue, paying attention to its shape. Tongue Sketch: 2\. In the center of the mouth, toward the back is a single round opening, the **esophagus**. This tube leads to the stomach. Use a probe to poke into the esophagus. 3\. Close to the angles of the jaw are two openings, one on each side. These are the **Eustachian tubes**. They are used to equalize pressure in the inner ear while the frog is swimming. Insert a probe into the Eustachian tube.                 To what structure does the Eustachian tube attach? \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 4\. Just behind the tongue, and before you reach the esophagus is a slit like opening. (You may need to use your probe to get it to open up). This slit is the **glottis,** and it is the opening to the lungs. The frog breathes and vocalizes with the glottis. Use your probe to open the glottis and compare that opening to the esophagus. 5\. The frog has two sets of teeth. The **vomerine teeth** are found on the roof of the mouth. The **maxillary teeth** are found around the edge of the mouth. Both are used for holding prey, frogs swallow their meals whole and do NOT chew. Run you finger over both sets of teeth and note the differences between them. 6\. On the roof of the mouth, you will find the two tiny openings of the **nostrils**, if you put your probe into those openings, you will find they exit on the outside of the frog. 8. Complete the table Structure Function Location ------------------- ---------- ---------- Vomerine Teeth Eustachian Tubes Tympanic Membrane Esophagus Glottis Tongue