Across
- 5. a body cavity lined with mesoderm
- 9. the innermost germ layer
- 10. an animal whose mouth is formed from the blastopore
- 12. one of a pair of structures in the throat region of a chordate
- 13. a hollow ball of cells that develops when a zygote undergoes a series of cell divisions
Down
- 1. the middle germ layer
- 2. a long supporting rod that runs through ta chordate's body just below the nerve cord
- 3. an animal that lacks a backbone, or vertebral column
- 4. a fertilized egg
- 6. a body cavity that is only partially lined with mesoderm
- 7. a body plan in which body parts repeat around the center of the body
- 8. the outermost germ layer
- 11. an animal that has a backbone