Across

3. Animal that lives on land and in the water.
7. A flying animal that evolved from the dinosaurs.
8. A cold blooded land animal that lays eggs.
10. An invertebrate that has jointed limbs and a segmented body. Spiders and flies are arthropods
14. A square hoop used to define a set area for counting a population.
17. Animal that gives birth to live young.
18. An animal that catches and eats other animals.
19. Energy from the sun used by plants in photosynthesis.
20. An animal that is caught and eaten by another animal.

Down

1. The natural world in which humans, animals, and plants live.
2. (4,5). A diagram that shows the transfer of energy as one animal eats another, it always starts with a plant.
4. A life essential chemical, like nitrogen, phosphorus or potassium.
5. An animal with a backbone.
6. The natural place where a plant or animal lives, like a forest, desert, or riverbank.
9. A self contained community that interacts with the environment.
11. An animal that eats meat.
12. A simple chemical necessary for all life to exist.
13. A group of animals living in the same place or having a particular characteristic in common.
15. A strip of ground along which ecological population measurements are made at regular intervals.
16. A solid object that has a square base and a point at the top.