Hypothesis: It is expected that individuals will move together and cluster to better improve their chance of survival and finding a mate.
Results:
It was found that the initial movement of all individuals, for the five replicates, was to the edge of the dish. However, once on the dishes edge, individuals would follow it around to other individuals on most occasions. The table below shows the percentage of individuals from each test that clustered after reaching the dish edge:
|
|
1
|
2
|
3
|
4
|
5
|
Average
|
|
Clustered (%)
|
100
|
50
|
50
|
75
|
75
|
70
|
|
Separate (%)
|
0
|
50
|
50
|
25
|
25
|
30
|
Table 1: Shows the percentage of individuals that clustered vs. stayed seperate over five replicates.
Once on the edge of the dish there is evidence that clustering becomes a factor. However, two replicates showed that only half of the individuals decided to cluster.
Discussion:
There was a clear trend of movement away from the petrie dish centre towards the edges in all five replicates. With no cover to hide under, individuals are completely exposed in the plates centre, leaving them vulnerable. However, by moving to the edge of the petrie dish they receive protection on one side.
Once on the side of the petrie dish, individuals could find each other and form a cluster of remain alone. On average a higher percentage of individuals were found to cluster together instead of stay alone.This supports the hypothesis that the unknown Risoid species clusters together. This may be done to better protect themselves or increase mating opportunities. However, a number of individuals were seen to prefer space. This could be associated with the competition for food and other resources when clustered together as a group. This suggests that the directional and interactive behaviour of the unknown Risoid species may be affected by whether individuals feel threatened, are searching for resources or have received reproductive stimulus.
Question 2: Do the unknown Risoid species demonstrate directional movement in the form of chemoreception and/or photoreception? Or is their movement relatively non-directional?
Method:
The same eight individuals were used from the first test, with 4cm petrie dishes, filtered seawater and four individuals per replicate. Three different tests were done to show the movement behaviour associated with different objects. Plant matter from the downstairs aquarium was used as an object that would demonstrate chemosensory. (Note: the marine plant was found in high abundance in the same tank as the unknown Risoid species population). Individual tests were also done with a clear and coloured piece of plastic to show if movement was associated with photoreception (Clean plastic). The initial movements were recorded (movement to object or dish edge). Observations were continued to confirm that movement was towards their preferred location. All tests were replicated five times with fresh filtered seawater to show patterns in behaviour.
Hypothesis: A higher percentage of movement towards the visible plastic when compared to the clear plastic will demonstrate photoreception; while chemoreception is evident from the movement towards the leaf/other individuals when compared to the plastics
Results:
The initial movements observed by individuals showed that objects did make a difference to the behaviour seen in experiment 1. There was evidence of movement towards the plant and coloured plastic over the five replicates, while, the clear plastic was shown relatively little interest. A percentage was calculated for each test replicate to show the percentage of individuals that moved towards the object (plant, clear or coloured plastic) rather than the petrie dish edge.
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|
1
|
2
|
3
|
4
|
5
|
Average
|
|
Plant (%)
|
50
|
50
|
75
|
50
|
25
|
50
|
|
Clear Plastic (%)
|
0
|
0
|
0
|
25
|
0
|
5
|
|
Colour Plastic (%)
|
50
|
50
|
25
|
25
|
0
|
30
|
The low recognition of the clear plastic resulted in all individuals moving straight for the petrie dish edge, once there they move around as seen in the first experiment with some clustering and some staying alone. Now and then an individual would come across the clear plastic and check it out before moving on.
Discussion:
The tentacles of the unknown Risoid species demonstrated use as mechanoreceptors in all experiments for feeling the surfaces they were coming into contact with. The movement towards objects during the experiments, rather than the direct path to the petrie dish edge demonstrated that either chemoreception or photoreception was being used. The percentage of individuals that went towards the coloured plastic was relatively low; however, it was shown to be much greater than the clear plastic. This demonstrates that individuals were using photoreceptors as part of its movement behaviour. A higher movement of individuals towards the plant matter, in comparison to the other objects, would suggest that chemosensory is playing a determinate role in the unknown Risoid species'. However, results were not consistent throughout the replicates. This may be because individuals were reused over a short period of time or simply because some individuals were searching for food, whilst others protection.