Amazon River Dolphin
American river dolphins are the largest of the river dolphins, with males averaging 2,550mm and females 2,010mm in length. Despite the weight of their body they are very flexible. The young are born slate grey and turn a blotchy pink as they mature. Bristle hairs on their snouts provide sensory information. They have small eyes, but in clear water their vision is reportedly very good. The pectoral fins are large and broad, and they are lacking distal and dorsal fins.
There is a breeding season in late October to early November, with births occurring 8.5 months later in May to July at the time of peak water levels. Young are 800mm at birth and in captivity grow 200mm a year. Length of nursing is unclear, but an indiviual was found with a nursing calf a year after its birth.
These animals are usually solitary or found in mother-offspring pairs. Loose aggregations form for feeding and mating. They are usually slow swimmers, but capable of short bursts of speeds up to 23 km/hr. These river dolphins are reported to be curious and playful, and even in the wild they may be tame with humans.
When the river systems flood, the dolphins go out over the land and manage to navigate their through trees to find theirway back to the rivers.
The river dolphin feeds on fish, river turtles, and crabs.
Economic Importance for Humans
There is little direct hunting of these river dolphins, but if one is found dead its fat is used for lamp oil, and its eyes and genetalia as love charms. The meat is not used. Fisherman use them to locate school of fish.
Human pressures are causing population concerns. Seine and gill nets pose a real threat to dolphins that get caught in them. Also, hydroelectric power stations are causing changes in fish concentrations and the isolation of dolphin populations within river systems. Another problem is that mercury, which is used in refining fluvial gold, is found in high concentrations in the fish the dolphins consume.
Intersting Facts about Amazon River Dolphin
Legend has it that the spirit of a drowned person enters the body of a river dolphin, and dolphins can change into beautiful young men on land. This may be part of the reason that there is little intentional killing of these animals.