2.5.1

Coral Reefs

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Coral Reefs

Corals are small animals that live in the sea. They require certain conditions for growth.

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Description

  • Corals are small animals called polyps.
  • Their body is sack-like and they have tentacles to sting predators around a mouth (entrance) to the sack.
  • They use calcium carbonate (limestone) to make an outer shell (exoskeleton) to protect themselves.
  • They use their tentacles to feed - normally at night time
  • Algae live inside the polyps and provide it with oxygen.
  • The algae are coloured. Polyps are generally transparent (see-through).
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Conditions needed for growth 1

  • Clear water that allows sunlight through.
    • When boats churne water and lift sediment, they can really hinder coral growth.
    • Coral does not like particles, sediments or pollutants in the sea water because these block out sunlight.
    • This is bad for growth.
  • Warm water temperatures of 20-32oC. Corals can survive at colder temperatures than this, but will not grow either quickly or well.
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Conditions needed for growth 2

  • Sunlight.
    • Coral have a symbiotic (mutually dependent) relationship with algae.
    • Algae provide coral with oxygen.
    • Algae need sunshine, so coral are only found where there is sunlight.
    • Corals grow best in brightly lit (sunlight) water about 5 to 10 metres deep.
    • They can also grow in depths of 90 metres.
  • Saltwater.
    • Coral does not grow near river mouths.
    • It needs salty conditions to thrive.

Jump to other topics

1Paper 1 - Changing River Environnments

2Paper 1 - Changing Coastal Environments

3Paper 1 - Changing Ecosystems

4Paper 1 - Tectonic Hazards

5Paper 1 - Climate Change

6Paper 2 - Changing Populations

7Paper 2 - Changing Towns & Cities

8Paper 2 - Development

9Paper 2 - Changing Economies

10Paper 2 - Resource Provision

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