Download Grasshopper Dissection External Observation

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Grasshopper Dissection
External Observation
Locate the head, thorax, and abdomen.
Observe the head.
Locate the two compound eyes and the three simple eyes.
1. Why do you think grasshoppers have two types of eyes? What could be the difference in their functions?
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Unit 4 - Energy
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2. Use your hand lens to locate the following mouth parts and then describe what their functions could be:
Mouth Part
Function: What does it do?
Labrum
Maxillae
Labium
Mandible
Locate the tympanum, or eardrums, on the thorax.
All insects have six legs. Locate front legs, middle legs and back legs.
3. What about the structure of the legs enables grasshoppers to survive in their environments?
4. Locate and label the two pairs of wings. How are wings useful in obtaining food?
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Unit 4 - Energy
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5. Find the tiny openings along the abdomen called spiracles. What do spiracles do? Can you drown a
grasshopper by holding its head underwater?
Internal Observation
Remove the three right legs.
Insert the point of your scissors under the top surface of the last segment of the abdomen and make a cut to
the right of the mid-dorsal line all the way to the head. Be careful not to cut the organs underneath.
In front of the thorax cut down the right side to the bottom of the grasshopper. Cut down between the next to
the last and last abdominal segments.
Remove the exoskeleton from the right side of your grasshopper.
Locate the large dorsal blood vessel that runs down the grasshopper's body.
Remove the muscles of the abdomen. Can you see the air tubes?
Carefully cut away muscle and tissue to expose the digestive system.
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Unit 4 - Energy
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Locate and label the parts of the digestive system:
Mouth, Esophagus, Crop, Gizzard, Stomach, Intestine, Rectum, Anus
Body Part
Function: What does it do?
Air Tubes
Esophagus
Crop
Gizzard
Stomach
Intestine
Rectum
Anus
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Unit 4 - Energy
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Grasshopper Reading
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Insects are arthropods (Phylum Arthropoda) with jointed appendages, segmented bodies, and an
exoskeleton composed of chitin. Insects are in the class Insecta, & are the largest and most diverse
group of animals on earth. Insects have three body regions (head, thorax, & abdomen), 3 pairs of
legs attached to the thorax, a single pair of antenna attached to the head and mouthparts adapted
for chewing or sucking. Insect legs are often adapted for digging, crawling, jumping, or swimming.
Some insects may have a single pair of wings or be wingless.
The genus Romalea is a large grasshopper common in the southeastern United States. The
development of wings gave grasshoppers advantages over other land invertebrates. They could
spread out into new areas, they could search larger areas for food, and they were able to fly away
and escape from predators.
Grasshoppers have three pairs of jointed legs. The front pair is used for walking, climbing, and
holding food. The middle pair is used for walking and climbing. The back pair of legs are used for
jumping. Grasshoppers breathe air which enters small lateral openings on the body called spiracles
and circulates in a system of ducts to all organs and tissues. Grasshoppers have one pair of
antennae that is used for sensing, one pair of large compound eyes that detect movement, and three
simple eyes that detect light and dark. Tympanum, or eardrums, on the thorax are used for hearing.
The grasshopper's digestive tract is specialized to eat plant tissue. The mouth parts 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 and other structures absorb the digested food. Undigested food then goes to storage in the
rectum, and then is eliminated out the anus.
Grasshoppers lay a large number of eggs, and the eggs hatch very quickly. This allows the
grasshopper population to increase rapidly.
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Unit 4 - Energy