Irrawaddy dolphins, Orcaella brevirostris (Owen in Gray, 1866), aka Mekong or Mahakam River dolphin, reach 2-2.75external link m in length. The color of Irrawaddy dolphins is dark blue to dark gray ranging to pale gray, with a pale ventral (under) side. They have a high rounded forehead and no beak. Their U-shaped blowhole is located to the left of the midline on their dorsal (upper) side and opens to the front, unlike other species. They have a small, blunt, rounded triangular dorsal fin and large flippers. Like other river dolphins their neck is highly flexible, which enables them to forage in shallow water. They have narrow, pointed, peg-like teeth about 1 cm in length in both their upper and lower jaws. Two unique anatomical features of Irrawaddy dolphins are that they do not have a cardiac sphincterexternal link and the stomach is subdivided into compartments. They are not acrobatic dolphins and are not known to bowrideexternal link; however they have been observed leaping from the wate