Whenever I see this picture I think of this:
| Creature | Swims | Walks | Flies |
| -------- | ----- | ----- | ----- |
| Dog | X | X | |
| Fish | X | | |
| Bird | | X | X |
| Duck | X | X | X |
Notice how for each combination of swimming, walking and flying, there is a living creature that can do just that, with the exception of swimming and flying.
Sure there are flying fish, but they glide rather than fly. Did evolution really forget to cover this niche?
I’m finding this discussion so interesting! It’s honestly something I’d never thought of at all, but it’s an excellent exercise for my brain. Gannets have evolved special protection for their brains when diving, btw. They hit the water at 60mph. I wish we’d evolved some cooler attributes than opposable thumbs and walking upright. Gills, for example. Ah well.