Across
- 3. the science of the relationship or organisms and their environment
- 4. the periodic variation in the surface level of the caused oceans , bays, and gulfs
- 6. micro organisms or bacteria able to live in absence of oxygen
- 9. the arrangement of formation in zones
- 11. the amount of salt in something
Down
- 1. locations near the equator hot or humid
- 2. an animal with a backbone
- 5. the production of light by living organisms
- 7. mollusk having one shell example; whelk
- 8. mollusk having two shells example; clam
- 10. living or active in the presence of oxygen
- 12. an animal without a backbone