Because they feel threatened; blood stops pumping into the eyestalks and they are therefore retracted back into the head, so the snail can protect them :)
No they don't.
snails protect their eyes because they roll down the tenticles which sheds them
The eyes of land snails are at the tips of their longer pair of tentacles, and the eyes of marine snails are at the base of these tentacles.
they are for seeing
*their
Yes, snails have eyes on the tips of their upper pair of tentacles, which are located on their head. These eyes can detect light and movement.
To see.
They move there eyes
Beacuase just like humans it hurts the snails eyes Beacause your hands have dirt on them and snails dont blink so it hurts the eye
Frogs retract their eyes to help protect them. By pulling their eyes into their sockets, they can shield them from potential harm or danger. This ability also allows them to create a more streamlined shape for swimming efficiently.
A snail's eyes can only detect light shades. This ability is to protect itself from predators; if a predator was looming over a snail, its shadow would cast upon it allowing the snail to sense the change and retract into its shell in time.
Hydra will retract their tentacles into their body stem when touched. This is a response inherent in the plants from many centuries ago. Hydra do not like to be touched and close to protect themselves.