OpenStax-CNX module: m19859
1
General Science
∗
Siyavula User
This work is produced by OpenStax-CNX and licensed under the
†
Creative Commons Attribution License 3.0
1 NATURAL SCIENCES
2 Life and Way of Living
3
4 EDUCATOR SECTION
4.1 Memorandum
• Locust:
• No, yes, 6
1. Large: 2
Small: 3
2. Three
3. Four
4. No. Forewings hard and leathery, rear wings soft/delicate and can be opened out to form a large
surface area
5. Like plastic, hard
6. Feelers
7. No. There are spiracles on each segment of the abdomen.
8. Yes. Mouth parts are located at the bottom of the head. Cutting edges and feelers.
9. 6 legs.
10. No. The rear legs are stronger.
11. No. The females and males dier. The female locust has an ovipositor and the male has a copulatory
organ.
12. Protection: hard external skeleton, but it can use the feelers for feeling. Does not lose moisture, can
cope without water. Can move around easily: walks, sometimes ies of jumps. Can look for food because of
its locomotive ability, can see, has good mouth parts.
13. The learner should draw from life. If possible, a real creature must be observed.
14. Life cycle: adult, eggs, larva, pupa
Assignment 3:
• Dependence on water: able to survive dry conditions, able to live in environments where there is
no vigorous competition from other animals. Exoskeleton prevents loss of moisture, eats plants that
contain sucient water.
∗
†
Version 1.1: Mar 5, 2009 7:05 am +0000
http://creativecommons.org/licenses/by/3.0/
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
2
• Obtaining food: locusts are able to move fast and far to look for food. Eggs can survive dry conditions
and hatch when the soil is becomes moist (rain) and plants are green.
• Insects that display complete metamorphosis: survive in the form of a pupa, eggs hatch when food is
available.
• Respiration: tubes in the body transport the gases. They remain moist (do not dry out as easily as
the earthworm).
• Senses and communication: smells and feels with help of antennae; has a tympanic membrane (eardrum)
on the rst segment of the abdomen, creates sound by rubbing the rear legs against the rough wings
(locust; other insects dier, but the main thing is that they are able to communicate).
5 Leaner Section
5.1 Content
5.2 ACTIVITY 8:
To investigate and describe the grasshopper's ability to survive [LO 1.1,
LO 1.2, LO 2.3, LO 2.4]
5.3 THE GRASSHOPPER
The grasshopper belongs to the largest group in the animal kingdom, namely the insects.
What do you already know about this group?
• Spinal column: yes or no?_____________________________________________
• Legs: articulated or not?______________________________________________
• Number of legs:_____________________________________________________
Investigation: Catch a few dierent types of insects and bring them to class. Form groups of two or three
and study the insect in the group of which the body parts can be distinguished easily. A grasshopper or a
cricket works well. Answer the following questions (try your best to give a good answer so that you can get
a good mark):
1. An insect has large as well as small eyes.
• Large: ___________________________________
• Small: ___________________________________
2. In how many main parts would you divide the body? _______________________
3. How many wings does the insect have? If the wings are folded against the
body, lift them up and look carefully. ______________________________________
4. Are all the wings the same? ___________________________________________
Describe. ____________________________________________________________
____________________________________________________________________
____________________________________________________________________
5. What does the insect's skin covering feel like?
____________________________________________________________________
____________________________________________________________________
6. What does the insect feel with?
____________________________________________________________________
____________________________________________________________________
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
3
____________________________________________________________________
____________________________________________________________________
7. Does the insect have a nose with which to breathe? Describe
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
8. Does the insect have a mouth? Describe.
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
9. How do you know that it is an insect that you are busy studying?
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
10. Are all the legs developed equally strongly? _____________________________
What do you observe? __________________________________________________
____________________________________________________________________
____________________________________________________________________
11. Do the tips of the abdomen look the same in all the insects of the same type? ___
Describe. ____________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
12. Insects are particularly well adapted to be able to survive under dierent circumstances. Describe
(refer to protection, need of water, movement, ability to look for food).
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
13. Make a drawing of the insect as seen from the side.
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
4
5.3.1 Build
Figure 1
The body consists of three main parts: the head, the thorax and the abdomen.
The insect has an exoskeleton that consists of a strong leathery material called chitin.
The three pairs of articulated legs are attached to the thorax.
Two pairs of wings are also attached to the thorax: the front ones are leathery and lie at against the
body; the hind ones are soft and fold underneath the front ones like fans.
• The head bears:
•
•
•
•
- two antennae (feelers) with which the insect feels;
- three small eyes that are called simple eyes;
- two large or compound eyes; and
- mouth parts.
• The abdomen has no attachments, except for small sexual organs at the tip that dier in the case of
the male and the female.
• There is a small spiracle (breathing opening) on each segment of the abdomen.
5.3.2 Movement
Insects are very mobile. Just think about the agility of a y and the distance that swarms of grasshoppers
can y.
The legs are articulated. The hind legs of the grasshopper are developed more strongly so that it can
jump.
The front wings fold open diagonally and balance the insect during ight (like the wings of an aeroplane),
while the soft hind wings fold open like fans and do the actual ying.
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
5
Figure 2
5.3.3 Feeding
The grasshopper is a herbivore with mouthparts that are very well adapted for this purpose. Amongst
others, there are two small feelers with which it can feel the food so that it can push the food into its mouth.
There are also two jaws with cutting edges that nely cut up the plant material. The grasshopper therefore
has biting mouthparts.
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
6
Figure 3
Other insects have the same mouthparts as the grasshopper, although the shape can dier greatly to
adapt to other ways of eating. For example, they can be licking (the y), sucking (some moths) or biting
(the mosquito).
5.3.4 Respiration
On either side of each of the rst eight abdominal segments is a spiracle. These openings lead to a network
of tubes (trachea) that branch throughout the whole body and transport air.
5.3.5 Maintaining a water balance
The exoskeleton of the grasshopper forms a watertight skin covering. This means that the body does not lose
moisture and therefore can survive in dry conditions. The plant material eaten by the grasshopper contains
sucient water.
Reproduction
In Grade 6 you learned that a fruit y undergoes a complete change of form, or metamorphosis, from the
time the egg hatches until an adult y has developed. Can you still remember the stages? Fill them in on
the illustration below.
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
7
Figure 4
The grasshopper does not undergo a complete metamorphosis. After the male and female have mated,
the female lays eggs in the ground with her ovipositor. The small grasshoppers that hatch look just like the
adults. They moult a few times as they grow. We therefore speak of incomplete metamorphosis.
5.4 The grasshopper and other insects in the ecosystem
5.5 Assignment 3:
Explain why the grasshopper and other insects are adapted to their environment particularly well.
Dependence on water:
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
Obtaining food (distinguish between the grasshopper and other insects that undergo a complete metamorphosis).
Grasshopper:
____________________________________________________________________
____________________________________________________________________
http://cnx.org/content/m19859/1.1/
OpenStax-CNX module: m19859
8
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
Insects that undergo complete metamorphosis:
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
Respiration (Tip: why are insects not as dependent on a moist environment as the earthworm is?):
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
Senses and communication (Tip: research whether grasshoppers can hear and make sounds)
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
6 ASSESSMENT
The learner will be able to act condently on curiosity about natural phenomena,
and to investigate relationships and solve problems in scientic, technological and environmental contexts.
Assessment Standard 1.1: We know this when the learner plans investigations;
Assessment Standard 1.2: We know this when the learner conducts investigations and collects data.
Learning Outcome 2:The learner will know and be able to interpret and apply scientic, technological
and environmental knowledge.
Assessment Standard 2.3: We know this when the learner interprets information;
Assessment Standard 2.4: We know this when the learner applies knowledge in a variation of a known
situation.
Learning Outcome 1:
http://cnx.org/content/m19859/1.1/