Name _________________________
AP Biology
Date ___________
Grasshopper Dissection
Grasshopper Dissection
INTRODUCTION
Grasshoppers belong to PHYLUM ARTHROPODA. The arthropods are easily
identified by their hard external skeleton and their segmented bodies. Examples of
classes within this Phylum are the Arachnids (spiders), Crustaceans (lobsters and
shrimp), and the Insects. Grasshoppers are members of the Insect Class. Insects
have three body parts and six legs. The insect class has the most species of any class
on earth. Man is very interested in these organisms because of their economic
impact. Insects destroy a large portion of our crops each year. They also play an
important role in the environment by helping to recycle both dead plant and animal
matter and acting as a major food source for animals and carnivorous plants. For
dissection purposes, the grasshopper is a good example of this class because of its
size and easily observed structures.
PRE-LAB QUESTIONS
1. The grasshopper belongs to:
- kingdom animalia, which means:
- phylum arthropoda, which means:
- class insecta, which means:
2. Why is the chitinous exoskeleton both an advantage and a disadvantage?
3. How are the legs of the grasshopper adapted to the area in which it lives and to its method of
eating?
MATERIALS
Preserved grasshopper, dissection tray lined with a paper towel,
dissection manual, dissection kit, hand lens, scotch tape
PROCEDURE
Work in pairs.
READ THESE INSTRUCTIONS BEFORE YOU BEGIN.
I. External Observation
1. Tap the EXOSKELETON with your fingernail. This hard, tough
material is made of CHITIN, a carbohydrate (polysaccharide).
Examine the joints in the skeleton. Note how they are flexible and
can freely move.
2. The exoskeleton has three parts: the HEAD, the THORAX, which is covered by a “saddle” called
the PRONOTUM, and the ABDOMEN. Note that the head has a wide range of movement, which
is advantageous because the grasshopper can better use its sense organs. The large
COMPOUND EYE has many facets or lenses. The three OCELLI, or simple eyes, are located
near the base of the long, segmented ANTENNAE.
3. Use your probe to push up the LABRUM, the
upper lip. Clasp it in the tweezers and, with a
firm yank, pull it out. Tape it to your lab and
label it. The two-piece upper jaw, the LEFT
AND RIGHT MANDIBLES, is now exposed.
Observe their jagged edges. Using your
tweezers, pull these out carefully and tape them
to your lab. Label them. Use your probe to find
the lower lip, the LABIUM. Observe the thin
LABIAL PALPS, sense organs that are attached
to it. Pull out the labium. Tape it to your lab
and label it. Finally, locate the two-piece lower
jaw, the LEFT AND RIGHT MAXILLAE,
attached to it. Pull out the two parts. Tape and
label them.
4. Observe the 3 pairs of jointed legs. They are
similar to yours in that they all have a FEMUR, TIBIA, and a TARSUS (a “foot”). Tape a
walking leg and a jumping leg to your lab. Label the segments of both.
5. Pick up the large wings. Observe the second pair underneath. Note how light and thin they are.
The anterior pair are the WING COVERS. The posterior wings are the FLIGHT WINGS.
6. Count the segments on the abdomen. Use the hand lens to find the SPIRACLES, one on each
segment side. They are the openings to the
TRACHEA, the internal air passageways.
7. Find the TYMPANUM, the oval eardrum, which
is located on the anterior of the abdomen.
8. Observe the posterior of the abdomen. If it is
pointed, the grasshopper is male. If the end is
forked, the grasshopper is female. The forked
posterior structure is called the OVIPOSITOR,
and is used when the female deposits eggs.
Compare the size of male and female
grasshoppers found in the class.
II. Internal Observation
The grasshopper's digestive tract is specialized to
eat plant tissue. The mouthparts hold, crush, and chew the food before it passes into the mouth.
From the mouth the food passes through the esophagus into the crop. The food is stored in the
crop. Next, food moves into the gizzard, where teeth made of chitin grind it up further. Food then
moves into the intestines where glands digest the food. Undigested food then goes to storage in the
rectum, and then is eliminated out the anus.
1. Using your scalpel, carefully remove the pronotum (Situated just behind the head, this is a
prominent, saddle-shaped structure with lateral lobes.) Observe the stringy muscles holding it
on.
2. Insert the point of your scissors under the top surface of the last segment of the abdomen and
make a cut to the left of the mid-dorsal line all the way to the head. Be careful not to cut the
organs underneath.
3. In front of the thorax, cut down the left side to the bottom of the grasshopper. Cut down between
the next to the last and last abdominal segments.
4. Remove the exoskeleton from the left side of your grasshopper.
5. Locate the large dorsal blood vessel that runs down the grasshopper's body.
6. Use your scissors to cut the muscles close to the exoskeleton. Locate the finely branched trachea
leading to the spiracles.
7. In the female, observe the presence of the numerous eggs, which look like grains of brown rice.
Note how much space they take up. In the male, a series of whitish tubes, the testes, are located
above the intestine.
8. Locate the gut, which runs the entire length of the animal. The MOUTH is located in the head
region. This bulges into a large area that contains the CROP, a storage area, and the GIZZARD,
a muscular grinding area. Posterior to the gizzard are located the fingerlike structures which
ring the gut. These are the GASTRIC CAECA, which produce digestive enzymes. Behind this is
the STOMACH, in which chemical digestion and most of the absorption occurs. The thin,
delicate tubules, called MALPIGHIAN TUBULES, ring the gut posterior to the stomach. They
aid in excretion of nitrogenous wastes. The tubules are followed by the hindgut areas called the
ILEUM, the COLON, the RECTUM, and the ANUS.
9. Cut through the exoskeleton over the top of the head between the left antenna and left eye to the
mouth. Remove the exoskeleton on the left side of the head. Find the dorsal ganglion or brain.
Answer the following questions on separate paper. Every student is expected to
submit one set of questions.
1.
2.
3.
4.
5.
6.
7.
8.
9.
What is the purpose of compound eyes? What is the purpose of simple eyes?
How is the third pair of legs adapted for jumping?
Describe the differences between the two pairs of wings (appearance & function).
How does the tympanic membrane help a grasshopper?
What system do spiracles open into on a grasshopper?
The grasshopper has an open circulatory system. What does this mean? Does the grasshopper
have any blood vessels?
What is the purpose of Malphigian tubules? Are they analogous to any structures in the
human body?
Recall our earthworm dissection. Earthworms did not have Malphigian tubules. What
analogous structure did they possess?
How did you determine the sex of your grasshopper?
Use chapter 32 in your text to answer the following questions:
10.
11.
What kind of symmetry does the grasshopper have? What does this imply about its movement?
Does the grasshopper have a coelom?
12.
When an insect embryo is developing, how many germ layers are present? (Are insects
diploblasts or triploblasts?)
Lab: Grasshopper Dissection
Group members:
Date:
Submit this page at the end of class. 1 per group.
Figure 1 - Grasshopper Head (Label
ALL parts.)
Figure 2 - External Grasshopper anatomy (Label
ALL parts.)
Table 1 - External Appendages of the Grasshopper (Attach ALL parts.)
Antenna
Labrum
Mandible
Maxilla
Labium
Forewing
Hindwing
Walking Leg
Jumping Leg