do horses have a seat?

So I was explaining to Nathan that we are going to the Peter's ranch tomorrow w/ Mrs.Barb. I told him we can ride the mule, horses, play w/ the ginuea, geese, dogs, tortoise or cows. I am rocking him and he says "Mom do horses have a seat on their backs?" I explained that we put the seat on their back so we can ride them easier. Then he told me he needed to put his "boots in the stir-ups" but that he wasn't big enough. I was cracking up. He was quiet for about 30 seconds then he said "mom, giraffes have a long neck, but they don't have seats?" So random.