A species of dolphin is born naturally blind in the Indus and Ganges rivers in South Asia. These dolphins have a highly sophisticated sonar system and swim on only one side of their body.

Dolphins can swim and sleep at the same time.

How does a dolphin sleep if it lives underwater but has to breathe air? The solution is a series of short naps. The dolphin's brain divides itself in two, that is, one half is asleep while the other half stays awake to get the dolphin to the surface for air.

Next to man, the porpoise is the most intelligent creature on earth.

Some dolphins can swim up to 40 kilometres an hour.

Source: www.amusingfacts.com