From TED Ed:

If you were a jackrabbit in the desert, you’d be glad to stumble across a cactus: the flesh of these plants is a water source for many animals. Known for their spines and succulent stems, cacti of all shapes and sizes have evolved to not just survive, but thrive, in some of the harshest desert climates on Earth. So how do they do it? Lucas C. Majure shares the prickly plant’s unique adaptations.

[TED Ed]