Turtles can%c2%a0%c2%a0%c2%a0themselves in their shells

Yes, turtles can protect themselves by retracting their heads, legs, and tails into their shells. This ability allows them to shield vulnerable body parts from potential predators.

but what is another word for that

Another word for a turtle retracting itself into its shell is "turtling" or "turtled".