Across
- 4. Most animals have _____ attached to their bones to help them move.
- 5. Birds have hollow _____ to help them fly.
- 8. Birds' wings are covered in _____.
- 10. Squid can move by squeezing out _____ of water.
- 11. Animals push on water by swimming with _____.
- 12. Animals push on air by flying with _____.
Down
- 1. Muscles _____ on bones to cause movement.
- 2. _____ cover the bodies of fish and help them glide through water.
- 3. Ducks, frogs, and other animals that live near water have _____ feet to help them swim.
- 6. _____ are special scales on the bellies of snakes that help them slither.
- 7. Animals push on land by walking and running with _____.
- 9. _____ are string-like structures that attach muscles to bones.