The Amazon

Norman D. Penny, Ph.D., Senior Collections Manager of Entomology

Beginning 17,000 feet high in the Peruvian Andes, only 120 miles from the Pacific Ocean, the Amazon River flows more than 4,000 miles to empty into the Atlantic Ocean. Fully 20 percent of all fresh water in the world flows out the mouth of the Amazon, and along the way it carves out a basin of 2.5 million square miles. The watershed includes 52 percent of the land area of Brazil and parts of eight other countries. Altogether the Amazon River Basin encompasses 40 percent of all South America. The island at its mouth that forms its delta is larger than Switzerland. There are 17 tributaries over 1,000 miles long. Finally, and perhaps most importantly, the basin contains the single largest tract of unbroken tropical forest anywhere on earth.

Geologically, the Amazon River has had an interesting history. Originally the river flowed west and emptied into the Gulf of Guayaquil in Ecuador. Africa was still attached to South America at that time and the part of the river east of Obidos flowed eastward into what is now the Niger River basin in Africa. Thus, the current Amazon Basin had four elements: the eastern drainage north of the river, the eastern drainage south of the river, the western drainage north of the river, and the western drainage south of the river. The flow of the river was blocked at the western mouth when the Andes Mountains rose. This led to the creation of a huge inland sea, further isolating the plants and animals on the northern and southern shores. Finally, the water level rose high enough that water broke through at Obidos and adopted its current configuration of flowing eastward into the Atlantic Ocean.

For eight years I studied the Amazon insect fauna for the Brazilian government. Since coming to the California Academy of Sciences, I have continued those studies. The hanging-flies of the Amazon Basin were described in a series of five papers. The lacewings of the Amazon Basin were described in a series of 11 papers. Four more papers are planned to complete the study.

Amazon Basin - Info

Amazon River and Its Drainage Basin

Amazonia From Space

California Academy of Sciences Entomology Department

Rainforest Alliance - Amazon Rivers Program Resources

World Checklist of Extant Mecoptera Species

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