Across
- 4. a person who is trained to travel to space
- 5. an underground layer of water
- 6. the study of very small life forms
- 11. power generated by water
- 12. a container of water for sea animals
- 13. an animal that lives on both land and water
Down
- 1. an object in space that orbits the sun
- 2. having a variety of life forms
- 3. a channel for carrying water
- 7. heat energy that comes from inside the earth
- 8. animals living in water
- 9. a substance harmful to life forms
- 10. study of the earth's features
- 14. the regions of earth that support life