Rivers
are important aquatic habitats that support millions of species of
organisms. Thousands of species of fish, mollusks, plants, algae, and
insects depend on river ecosystems. Only one species of dolphin is
native to a river habitat, however—the boto, or river dolphin, native to
the Amazon River. Here, a man plays with a wild boto near Manauas,
Brazil.
Photograph by Roberto Piccardi, MyShot
National Geographic Encyclopedia
A river is a large, (click here) natural stream
of flowing water. Rivers are found on every continent and on nearly
every kind of land. Some flow all year round. Others flow seasonally or
during wet years. A river may be only kilometers long, or it may span
much of a continent.
The longest rivers in the world are the Nile in Africa and the Amazon in South America. Both rivers flow through many countries. For centuries, scientists have debated which river is longer. Measuring a river is difficult because it is hard to pinpoint its exact beginning and end. Also, the length of rivers can change as they meander, are dammed, or their deltas grow and recede.
The Amazon is estimated to be between 6,259 kilometers (3,903 miles) and 6,800 kilometers (4,225 miles) long. The Nile is estimated to be between 5,499 kilometers (3,437 miles) and 6,690 kilometers (4,180 miles) long. There is no debate, however, that the Amazon carries more water than any other river on Earth. Approximately one-fifth of all the freshwater entering the oceans comes from the Amazon....
The longest rivers in the world are the Nile in Africa and the Amazon in South America. Both rivers flow through many countries. For centuries, scientists have debated which river is longer. Measuring a river is difficult because it is hard to pinpoint its exact beginning and end. Also, the length of rivers can change as they meander, are dammed, or their deltas grow and recede.
The Amazon is estimated to be between 6,259 kilometers (3,903 miles) and 6,800 kilometers (4,225 miles) long. The Nile is estimated to be between 5,499 kilometers (3,437 miles) and 6,690 kilometers (4,180 miles) long. There is no debate, however, that the Amazon carries more water than any other river on Earth. Approximately one-fifth of all the freshwater entering the oceans comes from the Amazon....
