This episode continues the study of mammals, and particularly those whose young gestate inside their bodies. Attenborough asks why these have become so varied and tries to discover the common theme that links them. Examples of primitive mammals that are still alive today include the treeshrew, the desman and the star-nosed mole. Insect eaters vary enormously from the aardvark, giant anteater and pangolin to those to which much of this programme is devoted: the bats, of which there are nearly 1,000 different species. These took to flying at night, and its possible that they evolved from treeshrews that jumped from tree to tree, in much the same way as a flying squirrel.
It’s sexy time with the arthropods! This week David Attenborough takes a look at the courtship rituals of the creatures beneath our feet. But lovebugs won’t want to take tips from these bugs. The male Chilean rose tarantula, for instance, weaves a silk mat; deposits sperm on it, then sucks that sperm into a finger-like appendage near his mouth before he looks for a mate. Then there’s the gruesome, but surprisingly effective, coupling of praying mantis. The cinematography is as amazing as ever, catching the mating battles of tramp ants and providing luminescent footage of the courtship dance of Tanzanian red claw scorpions.