How are camels capable of eating a cactus?
Rather than have people speculate with an amazing degree of authority, I can answer this with firsthand observations. I live in Arizona and until recently I had as many as ten camels just outside of Tucson. I had them for decades. We have a lot of cacti here and the camels would indeed eat many of them, though carefully and hesitantly.
Most cacti seemed to cause them pain and they would try to avoid the spines to get to the (apparently) tasty innards. You have to remember that camels have prehensile upper lips, split into two halves, that they can use much like two large fingers, though they cannot view them with their eyes. It is likely that these prehensile upper lips are very sensitive as the only way a camel can manipulate them is by using its sense of touch.
A Bactrian camel using its prehensile lips (above).
They really enjoyed prickly pear cacti and would even try to eat our really nasty "jumping cholla" often resulting in a cholla segment embedded in the front of their face. That clearly bothered them and caused pain. I'd have to use a comb to remove the segments (the cholla have extremely sharp barbed spines) or they'd be stuck to their face for a long time.
Their mouths are not "leathery" nor immune to pain. They will often tolerate the pain for the pleasure of eating the cacti and would move the material very carefully within their mouths.
The other thing I noticed is that they'd nibble at many cacti, especially prickly pear, until they had removed many of the spines. At that point they'd really go to work on eating the plant, often to a nub if it was a plant growing in their large enclosures, giving them time (sometimes weeks) to dedicate to the effort.
Dromedary camel eating a prickly pear cactus segment (above).
And as a bonus, this quote from the once living actor Marlon Brando:
"The most repulsive thing you could ever imagine is the inside of a camel's mouth."
You decide:
Not to sound arrogant, but why do people with no knowledge of a subject feel they can answer questions within that topic?
Camels can indeed occur in areas with cacti. Camels do not live in the Sahara. They may be used to cross areas of the Sahara, but they wouldn't survive there. They can be found in the Sahel in Northern Africa, other areas of Northern Africa, and can be found in the Middle East, Asia and the largest population can be found within the outback of Australia where they are feral, though the Australian government has been hard at work trying to eradicate most of them.
As for the other answers……..
https://www.quora.com/How-are-camels-capable-of-eating-a-cactus