Crown of Thorns starfish II

This task is about how observations inform theories.
Over the past 20 years outbreaks of the Crown of Thorns starfish have caused large amounts of damage to coral reefs in the Pacific Islands. Crown of Thorns starfish feed on the fast growing corals of the coral reefs. 
 
illustration: crown of thorn starfish

Question 1Change answer

The Crown of Thorns starfish have certain adaptations/features that help them survive and
reproduce in the coral reef environment.
a)  Explain in the boxes below how each of the adaptations/features could help this starfish survive.
 
illustration: Crown of thorn starfish
How could the colour of the starfish help it survive?
How could the bristles/thorns of the starfish help it survive?
How could the many legs of the starfish help it survive? 
Scientists wanted to work out why Crown of Thorns starfish have become such a problem.
One theory suggests that when there are fewer predators starfish numbers increase. 

Question

Scientists made these four observations. Two of these observations show that when there are fewer predators the starfish numbers increase [the predator removal theory].
Choose the two observations that support this theory. 

    • No starfish remains have been found in the stomachs of large predator fish on coral reefs

    • Triton shells (which can eat starfish) are heavily harvested for Pacific Island ceremonies

    • Overall numbers of puffer fish (seen eating starfish) are low on coral reefs

    • Whole starfish can regenerate from small pieces left behind when they are eaten.

Question

Choose the two observations that would not support the theory.
 

    • No starfish remains have been found in the stomachs of large predator fish on coral reefs

    • Triton shells (which can eat starfish) are heavily harvested for Pacific Island ceremonies

    • Overall numbers of puffer fish (seen eating starfish) are low on coral reefs

    • Whole starfish can regenerate from small pieces left behind when they are eaten

Question

Do you think there is enough evidence to support the theory?  

  • No starfish remains have been found in the stomachs of large predator fish on coral reefs

  • Triton shells (which can eat starfish) are heavily harvested for Pacific Island ceremonies

  • Overall numbers of puffer fish (seen eating starfish) are low on coral reefs

  • Whole starfish can regenerate from small pieces left behind when they are eaten.

    •  Yes

    •  No

Explain why you think this.

Question

Scientists decided to do some further observations. 
Choose one of the following observations.

    • Count the number of triton trumpet shellfish on reefs in areas that are inaccessible to people.

    • Observe how much of each Crown of Thorns starfish a triton trumpet shellfish eats.

    • Examine the stomach contents of the triton trumpet shellfish.

Explain how this observation would help support or would not help support the theory.
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