Across
- 2. For _____ they have inner skeletons made of bone.
- 5. Their _____ hatch in water.
- 6. For _____ their bodies have neither scales nor hair.
- 7. _____ means that they live on land and in water.
- 8. Their three-chambered hearts allow for _____.
- 9. They breathe with _____ when they mature.
Down
- 1. _____ is done by laying jelly-coated eggs.
- 3. For _____ they breathe with gills when young.
- 4. For _____ they use four limbs.