Why are cactuses prickly?

Lots of plants are smooth to the touch, and some are even soft and feathery like flowers! So why are cactuses prickly and sometimes even painful? We asked botanist Rachel Jabaily from Colorado College to answer this spine-tingling question.  Got a question that’s prickling at your brain? Send it to us at BrainsOn.org/contact, and we’ll help sharpen you up. See omnystudio.com/listener for privacy information.