Photographed in Agonda, Goa.
Dolphins are mammals, and have evolved from previously land-dwelling ancestors. The nostrils were at the end of the snout in the ancestral animals (as in all other mammals), and in the course of evolution, gradually migrated to the top of the head, and formed what is known as the "blow-hole".
The position of the blow-hole on the top of the head enables dolphins and whales to breathe air without having to stick their entire head out of the water.
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