Family Gaviidae
The family of birds called Gaviidae is composed of all species of Loons. Their Latin name means roughly "of the sea birds". They eat fish and are excellent swimmers and divers mainly because of their strong legs with large webbed feet. Since their legs are right at the back of their bodies, when they are chasing a meal under water, their feet don't bump into their tails or bodies.
This placement of their legs at thee back of the body is something they have in common with many mammals who live in water - such as seals and walruses. That seems logical, since they hunt under water in the same way.
[LH] {BI}