#Geographyandenvironment

Corals
- Corals are colonies of living polyp invertebrates and are hugely sensitive to temperature changes.

- When they get too hot, they lose their vibrant colour and die.

- Australia's Great Barrier Reef is the world's largest coral system.

- It is now so badly damaged

- It is listed by the International Union for Conservation of Nature (IUCN) as "critical", the worst category.

- Some subtropical corals thrive in warmer oceans because they form harder colonies, compared with their tropical corals.