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High on the rocky mountain tops away from the jungle, there are fewer predators for small toads to worry about. A pebble toad is only an inch long, and these rocks might seem a paradise for a toad. There are no snakes and it's even wetter than the jungle below. However, up here there are toad-eating tarantulas that ambush their prey. The pebble toad can't hop, but has a different defence - a unique ability to roll itself into a ball and bounce away from potential danger. It tenses its muscles, becomes rigid and turns itself into a 'rubber ball'. It's so tiny and weighs so little that bouncing down the steep rocks doesn't hurt it at all. Bizarre innovations like these are one of the reasons that amphibians and reptiles are so successful.