Coral reefs

Definition

Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures produced by corals. They are often referred to as the 'rainforests of the sea' due to their rich biodiversity.

5 Must Know Facts For Your Next Test

1. Coral reefs occupy less than 1% of the ocean floor but support about 25% of all marine species.
2. The three main types of coral reefs are fringing reefs, barrier reefs, and atolls.
3. Coral polyps have a symbiotic relationship with zooxanthellae algae, which provide them with nutrients through photosynthesis.
4. Coral bleaching occurs when corals expel their symbiotic algae due to stress factors like increased water temperatures and pollution.
5. Human activities such as overfishing, coastal development, and climate change pose significant threats to coral reef ecosystems.

Review Questions

• What percentage of marine species are supported by coral reefs?
• Name the three main types of coral reefs.
• What is coral bleaching and what causes it?

Related terms

Symbiosis:

A close and long-term biological interaction between two different biological organisms.

Zooxanthellae: Photosynthetic algae that live in symbiosis with coral polyps, providing them with essential nutrients.

Biodiversity: The variety of life in a particular habitat or ecosystem.