1. Stinging cell of a cnidarian

2. Algae that deposit calcium carbonate

3. Relating to the sea

4. Relating to the tropics

5. A ring-shaped coral reef

6. Brightly colored reef fish

7. A marine invertebrate that forms reefs

8. A type of marine mammal

9. Process that causes corals to lose their color

9. To become white or pale

10. The outermost layer of the Earth

11. A limbless cold-blooded vertebrate

12. A tube used to breathe underwater

13. A type of marine algae

14. To release eggs or sperm into the water

15. Hard and rigid in texture

16. Largest and deepest ocean

17. A ridge of rocks or sand at or near the surface of the water