Across
- 3. lack a backbone
- 9. symmetry with identical sides
- 12. fluid-filled body cavity
- 13. divides into two parts, regrows the missing parts
- 14. Platyhelminthes
- 18. sponges
- 19. symmetry where it can be divided like a pie
- 21. made of silica, calcium carbonate, or spongin
- 22. roundworm
Down
- 1. one-opening digestive system
- 2. unable to move from place to place
- 4. have a backbone
- 5. bump develops into a new individual
- 6. layer of cells between the ectoderm and endoderm
- 7. sea urchin
- 8. Mollusca
- 10. Annelida
- 11. I have tentacles
- 15. jellyfish
- 16. two opening digestive system
- 17. is the first step to having a brain
- 20. Arthropoda