Why do turtles have shells?

Answer: Protection from predators

Protection from predators ✓ — Correct! Defensive armor! Turtle shell (carapace + plastron): fused ribs and vertebrae covered by scutes (keratin plates). Functions: (1) Predator protection—hard barrier against bites, claws. (2) Retraction—head, legs pull inside. Modified skeleton—can't separate from shell (grows with turtle). Trade-offs: limits lung expansion (shell rigid), reduces speed. Box turtles: hinged plastron seals completely! Softshell turtles: leathery shell (different strategy). Shell evolved ~200 million years ago!

Storing water in shell — Wrong. Shell doesn't store water (myth). It's protective armor—fused skeleton providing defense from predators.

Amplifying hearing ability — Wrong. Turtle shells don't amplify hearing—turtles have poor hearing and rely mainly on vibrations. Shells evolved purely as defensive armor against predators.