Learning about cactus...

Those pesky rabbits are just trouble... I keep trying to catch them but there are more obstacles than success. I saw one and in trying to catch it (running as far as my leash would allow) I hurt my paw. There were these things sticking out of my paw and I couldn't walk... ouch, ouch, ouch! My people told me I stepped on a cactus... I don't know what that is but I suspect the rabbits had something to do with it - probably a trap they set for me.