Question: The Amazon Basin contains what percentage of known species (plants and animals) on Earth?
Answer Choices: A) 1% B) 10% C) 20% D) 45%
Correct Answer: B) 10%
Summary: The Amazon Basin is abundant in biodiversity. The number of known species on earth that have been formally identified is about 2 million species, making the Amazon home to about 200,000 of these. This includes roughly 40,000 plant species, 3,000 freshwater fish species and more than 370 reptile species. However, estimates for the total number of species on earth range between 5 million and 30 million. These extremely large estimates exist because of multiple studies that have been done in the Amazon rainforest that suggest there could be many, many more species on earth than previously believed. Perhaps the most significant study on this topic was conducted by Terry Erwin, a biologist that specializes in beetle populations. In the Amazon, Erwin sprayed pesticides into the forest canopy which caused any insect to fall to the forest floor (see picture here). After examining the fallen insects, he found a high number of undescribed species, as well as over 1,100 species of beetles alone from the canopy of a single species of tree (L. seemannii). Using the Amazon as an illustration for what could be living in other rainforests, he has estimated that the total number of species in the world could be much larger than the meager two million already identified. This leaves plenty of unidentified, “mystery” species that are still out there, many possibly living within the Amazon.
Sources: World Wildlife Fund; Amazon: World’s largest tropical rain forest and river basin; http://www.worldwildlife.org/what/wherewework/amazon/index.html#;
The Environmental Literacy Council; How many species are there?; http://www.enviroliteracy.org/article.php/58.html;
Terry Erwin; Tropical forest canopies, the last biotic frontier; 1983; Bulletin of the Entomological Society of America.