Name:
Date:
Frog Dissection Lab
Period:
PRE-LAB DISCUSSION:
Frogs or Anurans are classified as amphibians, meaning “both sides” or living on land
and water. Frogs have four life cycles starting out as an egg, then tadpole,
metamorphosis, and then adult. The adults are well suited for jumping due to the
large, long muscles and long ankle bones. The Australian Rocket frog can even jump
over 50 times its body length! Frogs also do not have a tail like other closely related
organisms such as lizards. The eyes of the frog have three protective membranes, one
of them being the nictitating membrane. Behind the eyes of some frogs are glands
that release poison toxins. Some of these toxins have been applied with medicine as
painkillers and are 200 times more potent than morphine. The respiratory system of
the frog is unique such that it can take in water and oxygen through its skin.
Therefore when the frog is under the water it can take oxygen in through the skin and
then transport it to the bloodstream or when it’s on land, it can breathe through the
nostrils or nares and force the air into the lungs.
ALTERNATE ASSIGNMENT & videos:
http://www.roketoyun.com/frog-dissection.asp
virtual lab: http://www.mhhe.com/biosci/genbio/virtual_labs/BL_16/BL_16.html
external & internal video: https://www.youtube.com/watch?v=9Y8Ysek4Vac
external only video: https://www.youtube.com/watch?v=u-LqS5AVRio
internal only video: https://www.youtube.com/watch?v=bOJyhk4QZvc
MATERIALS:
One frog specimen
Rubber Gloves
Safety Glasses
Dissection kit
Dissection tray
Paper towels
SAFETY:
Handle all specimens carefully and respectfully. Please be careful using the scalpel
and scissors. Clean all equipment completely when finished. Specimens have been
preserved in chemicals therefore safety glasses and gloves are required. If the
specimen or liquids contact skin, wash thoroughly.
DISSECTION ASSIGNMENTS:
Group Leader:______________________________________________
Double S (Sanitary Specialist):____________________________
Data Specialist:_____________________________________________
BEFORE DISSECTION:
1. Put on gloves and goggles.
2. Take tools out of kit and place on dissection tray
3. Return empty kit to Mrs. Taylor.
Name:
PROCEDURE:
1. External Anatomy
Dorsal side:
Date:
Period:
Ventral side:
Head:

Eye: Has a nictitating membrane that protects the eye and keeps it
moistened. Locate the nictitating membrane & write observation:

Tympanic Membrane: Located right behind the eyes and transmits sound
waves to the inner ear of the frog.

Nares: Nostrils located on the anterior portion of the head and can be
found on the inside of the mouth.

Mouth: write down observation
Skin: Observe the skin. Is it rough or slimy? Observe the limbs and write
down observations.
Skin:
Hind limbs & feet:
Fore limbs:
INTERNAL ANATOMY
Muscular system on leg:
1. Starting on the ventral side where the hind leg meets the
abdomen, grab the skin with the forceps and take scissors to cut
the skin off of the leg.
2. Peel the skin off of one hind leg to expose the muscles.
3. Flex and contract the hind leg observing the muscles.
Thoracic cavity:
1. Pin the frog ventral side up on the dissecting tray by pinning down each of the
limbs.
2. Lift the frog’s skin with forceps between the rear legs.
Name:
Date:
Period:
3. Make a small cut through the lifted skin with the scalpel. Take care to cut only the
skin.
4. Use the scissors to continue the incision up the midline all the way to the frog’s
chin.
5. Make sure the cuts are shallow as to not damage the underlying tissue.
6. Next make perpendicular cuts at the ends of the initial cut. One incision cutting
between the shoulders and the other incision between the hips.
7. Then carefully pull back the skin and pin it down. (you may need to use a scalpel
to separate the skin from the muscle layer.)
8. Observe the skin and how it can help in gas exchange for the frog. MAKE
OBSERVATIONS
9. Next make another incision following the same pattern as above and pin back
the muscle tissue.
10. If the frog is female, there may be many dark colored eggs in the abdomen or if
your frog is larger, there may be many spaghetti-like fat bodies.
11. Observe if present and then remove them to continue observing the rest of the
abdominal cavity.
WRITE OBSERVATIONS OF INTERNAL ANATOMY
1. Liver
2. Gallbladder (under the lobes of the liver)
3. 3 chambered Heart
4. Lungs
5. Stomach
6. Small intestine
7. Large intestine
8. Pancreas
9. Spleen
Name:
10. Esophagus
Date:
Period:
11. After you have located all of these organs, remove the stomach and look for
the Kidneys (located at the lower back of the frog near the spine).
12. Bladder (empty sac located at the lowest part of the body cavity).
13. Reproductive Organs (oviducts and eggs OR Sperm Sac)
CLEAN UP:
1. Contain all organs and tissues from the dissection and place inside gloves.
2. Raise hands for disposal of specimen.
3. Completely clean with soap and water and dry your dissection
instruments.
4. Clean and dry the dissection tray. Place a dry paper towel on the tray.
5. Place dry tools and pins on paper towel on tray.
6. When complete, bring your tools and the tray to be approved by the teacher.
7. Return all tools back to kits.
8. WIPE OFF TABLES WITH DISINFECTANT.
9. Return goggles.
10. Complete the lab observations and Dicey Dissection Follow Up.
Images and ideas from http://www.biologycorner.com/resources/dissection-cut.gif