In moments of great grief, that's where you look and immerse yourself. You realise you are not immortal, you are not a god, you are part of the natur… - David Attenborough

Penguins underwater look somewhat like dolphins, and indeed the two families have similar evolutionary histories. Dolphins are descended from air-breathing land animals, just as penguins are descended from air-breathing flying animals. Both subsequently took to swimming for their food. They became beautifully adapted and streamlined. And now, both are superlative swimmers and highly accomplished fishermen.

Members of the auk family, such as these guillemots and puffins... propel themselves, not with their feet like ducks, but with their wings, and they have paid a considerable price to be able to do so... Auks have had to evolve shorter, stubbier wings. That gives them a rather clumsy, whirring flight in the air, but it does enable them to "fly" underwater so well that they can outpace small fish.

You might think that a hornbill would have the most powerful excavation tool of all, but in fact its huge beak is a relatively delicate structure and no use at all as a chisel.