Like eye color, skin color is an example of polygenic inheritance. This trait is determined by at least three genes and other genes are also thought to influence skin color. Skin color is determined by the amount of the dark color pigment melanin in the skin.
The river dolphin is a group of aquatic animals that is specially adapted to the fresh water and are relatively smaller compared to the other dolphins.
They have evolved to survive in shallow waters and strong-river currents. These dolphins are not very widely disturbed and are found in certain deltas and rivers.
