 Well, OK, so we've let go of the snake, and the snake, I mean, it's having a go at going up this tree. And it's just incredible that the body can stay flat against the tree without just sliding straight off. I mean, it could take you a while. I've seen them go up trees quickly. But there, look. Now, can you see there? It's forced the ridge into that gap and created a groove. The ridges Mark's describing are part of the snake's belly. They help him get a good grip on the tree bark.