Animals

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Across
  1. 3. metamorphosis,undergoes up to three stages only
  2. 6. the union of the egg and the sperm cells
  3. 11. Animals that are born alive
  4. 12. an organ attaches the unborn youg animal to the mother
  5. 14. Animals has pouches
  6. 15. series of changes
Down
  1. 1. Animals with backbone
  2. 2. The simplest group of invertebrates
  3. 3. Animals without backbone
  4. 4. the union of sperm cell and egg cell
  5. 5. the study of animals
  6. 7. reproduction by one parent
  7. 8. those mammals whose young develop completely inside their
  8. 9. Keeping the eggs warm until they hatch
  9. 10. Animals that lay eggs
  10. 13. the body
  11. 16. body