Activity: Friend or Foe - Are harakeke caterpillars fighting for the same food? Level 4
Achievement Objectives - Whāinga Paetae: Te Aka
4.2 Recognise that there are biological processes common to all organisms, and that those occur in different ways in different species. Te Marautanga o Aotearoa: (p.101) Te Ao Tūroa, Te Rauropi 1 & 2
Learning Outcome
I will be able to:
- make measurements between the midrib, notches and windows on a leaf
- record my measurements and make a graph of these results
- use these results to find out if two different types of caterpillar eat the same type of food
- share my results with others and make a note of any differences.
Success criteria
| Success criteria | Self-assessment | Peer assessment | Teacher assessment | ||||||
| I can make measurements of the notches and windows on a leaf. | |||||||||
| I can record my measurements and make a graph of these results. | |||||||||
| I can use these results to find out if two different types of caterpillar eat the same type of food. | |||||||||
| I can share my results with others and make a note of any differences. | |||||||||
There are two types of caterpillar that feed from the harakeke leaf. One caterpillar makes notches in the leaf and the other makes holes or windows. Are these two caterpillars competing (fighting) for the same food? By carrying out the following activity you will be able to answer this question.
Find either a harakeke bush or cabbage tree that has lots of holes and notches in the leaf. Avoid taking measurements from the tip and the bottom of the leaf. For each notch and window make four measurements from the midrib as in the diagram below.
Repeat your measurements until five windows and notches have been recorded in the table below. Notch measurements are recorded in the red part of the table and window measurements in the green part.
Distance from the midrib (mm) to:
| 1 start of notch | 2 edge of leaf | 3 start of window | 4 end of window |
|
|---|---|---|---|---|
| Notch | 0 | 0 | ||
| Window | 0 | 0 | ||
| Notch | 0 | 0 | ||
| Window | 0 | 0 | ||
| Notch | 0 | 0 | ||
| Window | 0 | 0 | ||
| Notch | 0 | 0 | ||
| Window | 0 | 0 | ||
| Notch | 0 | 0 | ||
| Window | 0 | 0 |
Draw a bar graph of your results or use the attached spreadsheet to record your results and make a graph.
The graph below is an example of what your results might look like.
Note: If the red and green bars overlap, this means that the caterpillars are competing for food. Do any of these bars overlap?
- Do the bars of your graph overlap?
- Do you think your caterpillars are competing for the same food? Why?
- Are your group’s results similar to the rest of the class? If they are different, why do you think this is so?
- Do the two caterpillars eat exactly the same part of the leaf?
- What do you think would eventually happen to the caterpillars if they ate exactly the same part of the leaf?
Teachers’ notes: Harakeke window caterpillars cannot eat a window right to the edge of the leaf. If they did so, then either the notch or window caterpillar would become extinct. This is because the two caterpillars would be eating exactly the same part of the leaf. This rule applies for all living things.