Across
- 4. Tiny internal blood pipe
- 5. Heavy body skeleton frame
- 6. Engine for body movement power
- 8. Long distance running power
- 9. Natural animal milk sugar
- 11. Gas for breathing and energy
- 12. Random genetic code change
Down
- 1. Natural skin sun umbrella
- 2. Dangerous space sun rays
- 3. Survival of the fittest
- 7. Internal blood oxygen tank
- 10. Heavy planet pulling force