Most brightly coloured dolphin

The world’s most brightly coloured dolphin is the Chinese pink dolphin (Sousa chinensis chinensis), which is a subspecies of the Indo-Pacific hump-backed dolphin. A popular if nowadays increasingly endangered tourist attraction in Hong Kong harbour, the adult of this dolphin, which measures 2.2–2.5 m (7 - 8 ft) long and weighs 150–250 kg (330-550 lb), is noted for its bright pink-coloured skin. Its eyecatching colour is not due to skin pigmentation, however, but instead it results from the presence just beneath the surface of numerous blood vessels that are used for thermoregulatory purposes. They help to prevent the dolphin from overheating during exertion by dilating, releasing heat that has built up inside the dolphin’s body. When newly born, however, the Chinese pink dolphin is actually black, changing to grey as a youngster, and ultimately to pink as it matures. Also pink in colour, but rather less bright, is the skin of the Amazonian river dolphin or boto (Inia geoffrensis).