Blind Cavefish - Deep underground, in submerged caves, there is no light. Because there is no light, there are no plants and almost nothing to eat. Yet life survives here. The top predators in these sunless ecosystems are tiny blind cavefish, only a few inches long. They are extremely rare, only found in the dark recesses of caves. Jonathan joins Christine Loew, a veteran cave explorer, on a mission to film this incredibly rare fish. Coral Reefs - Often referred to as the "rainforests of the sea," coral reefs are incredibly important to life in shallow tropical oceans. But what exactly is coral? How does it grow? And why is it so important? Jonathan answers these questions and more in this beautifully-shot segment on coral reefs, filmed all over the world from the Caribbean to the Philippines, Australia and Indonesia. Bottom-dwelling Sharks - When most people think of a shark, they think of an animal like the Great White or a reef shark. But there are hundreds of small, bottom-dwelling sharks like the Wobbegong that blend in to the bottom to hunt as ambush predators, or simply spend most of their time resting on the bottom. Jonathan travels from Australia to Indonesia looking at interesting sharks that don't look like sharks!