Hi there! Let me tell you about saguaros. Saguaros are big, tall cactuses that live in the desert, where it's very dry. Their bodies have wrinkles and ribs, which look like big folds or lines on the outside.
When it rains, the saguaros soak up lots and lots of water. The wrinkles and ribs help by stretching out and getting bigger, so the saguaro can hold all that extra water inside like a big water balloon. Then, when the sun comes back and it gets dry again, the saguaro uses the water it stored to stay alive!
So, the ribs and wrinkles are like special stretchy pockets that help saguaros save water for when they really need it.