Biology 11
Purpose:
Grasshopper Dissection
Name:
to investigate all the major internal and external characteristics of the insects (an Arthropod)
Materials:
Dissecting pan
Dissecting kit
Dissecting pins
Grasshopper specimen
Method:
Part 1: External Anatomy
1. Place preserved grasshopper on a dissecting pan. Identify the following structures using the
grasshopper visual guide.
antenna
compound eye
simple eye (ocelli)
tympanum jumping legs
jaws
walking legs
palps spiracles wings
ovipositor (female only)
claspers (male only)
head
thorax
abdomen
2. You can tell the sex of your grasshopper in 2 ways. Use the instructions below to determine
the sex of your grasshopper
a) Females have an ovipositor which she used to dig a hole into the dirt to deposit her eggs
Males have small claspers which are used during mating
b) When mature, the female is twice the size of the male.
3. Grasshoppers are herbivores and their mouth parts are modified for this way of life.
Carefully remove each mouth piece as instructed. Remove the mouth parts in order as
described using your forceps. Remove the labrum (upper lip) by getting forceps under it as
far up as you can and then carefully pulling it out. Do NOT rip! In a similar fashion remove
the labium (lower lip). Next remove the maxilla, one at a time, together with its sensory
palp. The mandibles are next and the hardest to get out. Firmly hold onto the grasshoppers
head while pulling on one mandible with your forceps. It will take a good tug to get it out –
do NOT rip its head off! Remove the other mandible in the same way. This leaves only the
hypopharynx (tongue) which comes out easily.
Part 2: Internal Anatomy
1. Remove the 3 legs on the grasshopper’s left side where they join the body. Beginning at the
posterior most segment, make a mid-dorsal incision all the way up to the front of the thorax
(back of the head). Be careful not to cut too deeply as you can destroy the organs just below
the exoskeleton. Cut along the side of the thorax around to the ventral surface. Now open
the “flaps.” There are usually some muscle attachments that you will have to cut away with
your scalpel. Use pins to secure the flaps.
2. The hearts are difficult to see and may be destroyed upon opening as they are along the
dorsal surface of the animal. Posterior to the hearts are the egg (female) or male gonads.
Remove these to expose the digestive system.
3. Locate the mouth and anus. The digestive tract connects these two points. Just after the
mouth is the esophagus which leads to the storage crop. The crop connects to the thicker
gizzard which helps to grind the food. The gizzard leads to the stomach which leads to the
intestine and the anus. Around the stomach is the gastric caeca which empty enzymes into
the stomach.
4. Locate the thin-walled traechids (tubes) that connect internally to the spiracles which are
the external openings used to transport air into the grasshopper’s tissues. Notice also, in
the area of the intestine, the fine thread-like Malpighian Tubules – these are the kidneys.
5. Cut the esophagus and the anus and remove the entire digestive system in one piece. Cut a
V shaped notch in the back of the head and remove the neck muscles that extend into the
head. In the area between the eyes and antennae inside the head, locate the brain, which
appears as a small white mass. Locate the ventral nerve cord connecting to the brain.
Follow the nerve cord all the way to the last abdominal segment. You will see bulges – these
are the called ganglia (nerve masses that help co-ordinate the grasshopper’s actions)
6. Now that you have found each of the following structures, label them on the lab sheet.
- Hearts
- Gastric caeca
- Eggs or male gonads (depending on sex
- Intestine
of grasshopper)
- Traechids
- Mouth
- Spiracles
- Anus
- Malpighian Tubules
- Esophagus
- Brain
- Crop
- Ventral Nerve Cord
- Gizzard
- Ganglia
7. Wash all equipment and return to the proper storage place. Dispose of the grasshopper as
per your teacher’s instructions.
Analysis:
1. Label the external features on the diagram below:
2. The sex of my grasshopper is: _______________________________. I know this because:
3. What is the function (not structure!) of each of the mouth parts:
Labrum:
Labium:
Maxilla:
Mandible:
Hypopharynx
4. Label the internal structures on this female grasshopper
5. Complete the following table:
Characteristic
Grasshopper Equivalent
Number of body regions
Is the body segmented?
Number of walking legs
Number of jumping legs
Are the appendages jointed?
Type of skeleton
Are there fused body regions?
Number and type of eyes
Number of antennae
Number of wings
Type of respiratory organ
Are the sexes separate?
Location of main nerve cord
Type of circulation
Location of heart
Excretory organ
6. What have you learned from this lab about grasshoppers? About arthropods?