Create a reservation and keep people out of it.
It does get eaten. By humans and camels and such... But normal animals don't because they have little pointy things that jab your face. It hurts a lot!
The Barrel Cactus s beneficial to Humans because it makes oxygen and oxygen is what we breathe
Cactus fruits
they have the spines to protect them from your face
Within the protection of the cactus needles.
The rare "Lownds" cactus produces milk that can be consumed by humans.
Yes, because based on research, cactus has an ability to lessen the radiation from computer, so best if you'll be putting a cactus beside of your computer.
Some animals have special rough mouths that protect them from the hard pointy needles of the cactus. Like, a collared pecary
The cactus is one of the few plants found in the desert, and in order to survive it needs a massive amount of water. Since it does not rain all year round in a desert, cacti store water when it does rain. So the needles on the cactus protect their water-rich flesh from other things in the desert.
They found the early humans.
A cactus adapts to its environment by losing its spines to reduce water loss and protect itself from animals.
There are several answers, depending on the spikes. Answers include:To protect the plant from herbivoresTo provide a layer of still air, to protect the cactus skin from excessive heatTo provide shade to the cactus skinOverall, the purpose seems to be related in some way to the plant's survival strategies.