The Amazon River

Along its length of 6400 Km, 4,000 miles, the River Amazon changes from being 320Km / 200miles wide at its estuary to between 2-5km (1-3 miles) wide inland.

Facts and Figures

In the rainy season, the river overflows and floods the nearby forest for as long as 6 months of the year.

It carries the greatest volume of water of any river in the world.

Deep in the forest it splits into over a thousand smaller rivers and streams. These are fed by the water from the Andes and the rainfall draining from the forest floor.

It is the main water route in South America and is used for transport, for industry and by the millions of people and animals that live in it and along its banks.

The river is used as a water supply for industrial processes and to carry away discharged effluents. It is used to float materials along parts of its length, especially logs and is the home to fish that are caught in many areas on a commercial scale.


There are 2,000 - 3,000 species of fish in the Amazon - ten times as many as in Europe. Many of the fish eat fruits and seeds that fall into the water. The Tambaqui fish can eat up to 1 kg (2.2lb) of seed each time they feed. They have strong jaws and teeth which crush the seeds.

Arapaimas are the biggest freshwater fish in the world. They grow to at least 3m (approx. 10 feet) long and weigh up to 200 kg (440 lb). Most Piranhas eat seeds and nuts but some eat meat. They swim in large groups and can eat an animal in a few minutes!

The largest animals in the river are the Manatees. They grow to about 2.5m ( 8 feet) long and scientists think they are distant relatives of elephants. They eat about 40kg (88lbs) of plants a day. They close their nostrils under water and can stay there for about 1 hour. They taste and smell things with their tongues.

Electric eels kill fish and other animals with shocks of up to 650 volts - enough to stun a horse.

Caimans, a type of crocodile live in the shallow waters near the bank. They have been hunted for their skins and eggs and are now rare. Giant otters build dens in the river banks and mark their home range with droppings. They live in groups of about 15 animals, eat fish from the river and hum and chuckle to each other when they swim.

The mud and vegetation on the river bed provide a habitat for thousands of crustaceans and small fish which feed the complex foodchain along the river. 2 types of Amazon River Dolphin are found and they enjoy sporting in the water using their sonar system to communicate with each other. Red Ibises poke their heads into the mud to search for food and the Amazonian Kingfisher sits quietly waiting to pounce on his victim as it basks in the warm waters!

Oxygenation of the water is essential to maintain the balance of this complex ecosystem and any contamination, especially by heavy metals will have an effect on the oxygen uptake by both animals and plants. The level of inter-dependence is very high and the ecosystem exists in a state of balance. Any change will soon manifest itself along the foodchain.