Ecology Crossword by Parker

2. A close relationship between species, where one organism lives on or inside another organism, the host, causing it some harm.
5. A biological community of interacting organisms and their physical environment.
6. An animal that naturally preys on others.
8. A group of beings living in the same place.
11. A species moving to a foreign environment.
13. The process of change in the species structure of an ecological community over time.
14. An animal that is hunted and killed by another for food.
15. Relating to living things.
16. Interaction between two different organisms living in close physical association.
17. All the inhabitants in a particular area.
18. An association between two organisms in which one benefits and the other derives neither benefit nor harm.
19. The branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
20. A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
21. The preying of one animal on others.

1. A measurement of population per unit area.
3. A rivalry where two or more parties strive for a common goal which cannot be shared.
4. Not derived from living organisms.
7. Species which are the first to colonize barren environments or previously biodiverse steady-state ecosystems.
9. The ecological interaction between two or more species where each species has a net benefit.
10. A species leaving one are to live in another.
12. Anything that constrains a population's size and slows or stops it from growing.