1. pets
2. reptiles

Frog Dissection
Background Information
Amphibians, such as frogs, are examples of animals that have structural adaptations for living in or near
water and for living on land. As tadpoles, they have gills, but adult frogs have lungs. Tadpoles have tails,
but adult frogs have legs. Many changes occur in the metamorphosis of a tadpole. The structures that
frogs have depend in the stage of the frog’s life cycle. In this lab, you will dissect a frog in order to
observe the external and internal structures of frog anatomy.
DAY ONE
1-The frog life cycle:
Create a game (cards, flipbook, memory game, etc…) or manipulative that will teach First graders about
the life cycle of a frog. Your activity needs to incorporate color, pictures and a description of what is
happening at least the 5
stages .
DAY TWO
2-External Anatomy of the frog
 GET A FROG FROM YOUR TEACHER.
 RINSE AND PLACE IN DISSECTING TRAY
a) Locate, observe
and label the
external parts
and organs of
your frog.
10
*YOU NEED
TO BE ABLE
TO LOCATE
AND NAME
THE PARTS
FOR THE
TEST*
b) Write the function of the labeled parts:
Part
Mouth
Hindlimb
Forelimb
Eye
Digits of the forelimb
Tympanum
Web foot
Chromatophores
Nictitating Membrane
External Nares
Function
c) Observe the dorsal and ventral sides of the frog. Dorsal side color:_____________________________________
Ventral side color:_____________________________ How does the frog use this adaptation?_________________
________________________________________________________________________________________________________________
d) Examine the hind legs: How many toes are present on the foot?__________ Are they webbed?_________
How does the frog use this adaptation?____________________________________________________________________
e) Examine the forelegs: How many toes are present on the foot?__________ Are they webbed?_________
How does the frog use this adaptation?____________________________________________________________________
3-Measurements
a) Measure the length of the foot and leg of the frog. Compare this to the length of your own foot and
leg.
Frog
You
Foot length
Leg length
Ratio of foot/leg
b) How does the ratio of the foot/leg in frogs and humans compare? Is this an advantage or
disadvantage for the frog? Why?
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
c) Use a ruler to measure your frog, measure from the tip of
the head to the end of the frog backbone ( do not include the legs
measurement). Compare the length of your frog with other frogs.
Your
frog
(cm)
Frog 2
Frog 3
Frog 4
Frog 5
Average=total/5
d) Convert the average measurement from cm to mm (1cm=10mm):
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
e) Convert the average measurement from cm to m (1m=100cm):
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
4-Other external observations
a) Feel around the body cavity of the frog. DO NOT SQUEEZE TOO HARD. What major part of the
skeletal system is missing in the frog? Is this an advantage or a disadvantage? Why?
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
b) Just behind the eyes on the frog’s head is a circular structure called the tympanic membrane. The
tympanic membrane is used for hearing. Measure the diameter (distance across the circle) of the
tympanic membrane.
Diameter of tympanic membrane: _____________________cm
Compare the diameter of your tympanum with other frogs. Determine if the frogs are male or
female.
Your frog (cm)
Frog 2
Frog 3
Frog 4
Frog 5
Male tympanum is larger than female.
c) Another way to determine the frog’s sex, look at the hand digits, or fingers, on its forelegs. A male
frog usually has thick pads on its "thumbs," which is one external difference between the sexes, as
shown in the diagram below. Male frogs are also usually smaller than female frogs. Observe
several frogs to see the difference between males and females.
Frog gender:__________________________
Teacher Check:_______________________
d) Feel the frog’s skin. Is it scaley or is it smooth?______________________________________________________________ _____
Moist or dry? _____________________________________________________________________________________________________________

PLACE YOUR FROG IN A BAG, CLEAN YOUR SPACE and MATERIAL, DRY ALL TOOLS.
DAY THREE


GET YOUR FROG AND PLACE IN THE TRAY
WEAR YOUR SAFETY GOGGLES
4-Anatomy of the Frog’s Mouth
a) Feel around inside the mouth. Are there teeth on the top jaw? _________________________________________________
b) Are there teeth on the bottom jaw? ________________________________________________________________________________
*Follow the instructions for cutting open the mouth*
c) Describe how the tongue is attached to the jaw. How does that compare to the way a human’s
tongue is attached?
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
d) Consider how a frog captures its food. Why would it be an advantage for the frog’s tongue to
attach where it does?
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
e) The tip of the tongue in a live frog is sticky. What would be the advantage of this?
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________
f) In the center of the mouth, toward the back is a single round opening. This is the Gullet. This
tube leads to the stomach. Use a probe to poke into the gullet/esophagus.
g) Close to the angle of the jaws 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? _______________
________________________________________________________________________________________________________________________
h) Just behind the tongue, and before you reach the gullet is a slit like opening. This slit is the glottis
and is the opening to the lungs. The frog breathes and vocalizes with the glottis.
i) The frog has two sets of teeth. The vomarine teeth are found on the roof of the mouth. The
maxillary teeth are found around the edge of the mouth. Both are used for folding prey, frogs
swallow their meals whole and do not chew.
j) On the roof of the mouth, you will find two tiny openings, if you put your probe into those
openings, you will find they exit on the outside of the frog. These are the internal nares.
k) Complete the chart below
Structure
Vomarine teeth
Eustachian tubes
Tympanic membrane
Esophagus
Glottis
Tongue
Function
l) Locate, observe and label the mouth parts.
*YOU NEED TO BE ABLE TO LOCATE AND NAME THE PARTS
FOR THE TEST*





Internal nares
Glottis
Vomerine teeth



Gullet
Tongue
Eustachian tube opening
PLACE YOUR FROG IN THE BAG.
CLEAN YOUR SPACE AND MATERIALS. DRY ALL YOUR TOOLS.
DAY FOUR



Eye Socket
Vocal sac opening
Maxillary teeth
5-Internal Anatomy of the Frog
 WEAR YOUR SAFETY GOGGLES
 FOLLOW THE INSTRUCTIONS IN THE BOOKLET FOR THE DISSECTION.
 YOU WILL BE USING SCISSORS TO CUT YOUR FROG.
Heart of the Frog
Observe and label the following parts.
 Right Atrium

 Left Atrium

 Ventricle

Vena Cava
Conus Arteriosus
Left Truncus Arteriosus


Pulmonery Vein
Sinus Venosus
7
5
1
1-How many chambers does the frog heart have?(total of all atrium & ventricle)
________________________________________________________________________________________________________________________________
2-Explain why in the frog’s heart the ventricle has a thicker wall than the atria.
________________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________________
Digestive System of the Frog

FOLLOW THE INSTRUCTIONS IN THE BOOKLET FOR THE DISSECTION.
Observe and label the following parts:
 Anus

 Cloaca

 Esophagus

 Gall bladder

Gullet
Large intestine
small intestine
Mouth lining




Liver
Spleen
Pancreas
Stomach
*YOU NEED TO BE ABLE TO LOCATE AND NAME THE PARTS
FOR THE TEST*
Questions
1. What does the cloaca do? ________________
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
2. What does the small intestine do? _______
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
3. What does the large intestine do? _______
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
4. What three structures lie underneath
the liver? ___________________________________
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
5. List the path that food travel after it has entered the frog's mouth. What is the first place it goes after
it has been eaten? ________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________
6. How many lobes does the liver contain? _______________________________________________________________________
7. What is the shape of the stomach? _____________________________________________________________________________
Urogenital System
Determine if your frog is male or female?________________________________________________________
Label the frog corresponding to the appropriate gender:
Fat bodies
Kidneys
Testis (M)
Cloaca
Urinary bladder
Ureter
Ovary with eggs (F)
Oviduct (F)
1
4
6
3
5
The Brain ( if we have time)
Observe and label the following parts
Cerebellum
Cerebrum
Medulla oblongata
Olfactory lobe
Optic lobe
Final Questions
1. List 3 adaptations that permit the frog to live on land successfully.
________________________________________________________________________________________________________________
________________________________________________________________________________________________________________
________________________________________________________________________________________________________________
2. List 3 adaptations that permit the frog to live in water successfully.
________________________________________________________________________________________________________________
________________________________________________________________________________________________________________
________________________________________________________________________________________________________________
3. Write a few sentences to explain at least 3 things that you learned.
________________________________________________________________________________________________________________
________________________________________________________________________________________________________________
________________________________________________________________________________________________________________