MadSci Network: Zoology

Re: How many animals have become extinct?

Area: Zoology
Posted By: Kelleen Flaherty, Staff, Biology/Invertebrate Zoology expert
Date: Wed May 14 12:51:09 1997
Area of science: Zoology
ID: 863107764.Zo

This is a very important question to ask! Extinction is a critically important topic in biology that needs far more attention than it is getting, and it is really encouraging to see kids in elementary school interested in the topic!

I wish I could give you a definite answer to your question, but the truth is: no one knows. The fact that no one knows makes the whole idea of extinction even scarier, and I'll tell you why:

First of all, we don't even know how many species there are! Scientists have identified and catalogued around 1,500,000 to 2,000,000 species (of animals and plants), most of which are insects (most of which are beetles). However, those are only the species that have been identified and described, many, many, many more exist - some scientists think there are 10 million (10,000,000) species on Earth, and others think there are 100 million (100,000,000) species on Earth! Biodiversity (the number of living organisms on Earth) is an incredibly hard thing to count. There are places on the Earth that have hardly been explored at all where diversity (the numbers of species) is extremely high, places like the tropical rain forest. The really scary thing is that, mostly as a result of the activity of human beings (pollution and destruction of the environment), lots of these species are going extinct before we even get a chance to identify them in the first place!!

Dr. Edward Wilson is a famous scientist at Harvard University who studies biodiversity (he has done a lot of research on ants!). He guesses conservatively that in the next 25-30 years we can lose up to one-fifth of all the biodiversity on the planet! This works out to about 4,000 butterflies and 2,000 birds going extinct by the time you have kids in elementary school! Estimates vary, but different sources claim that species are going extinct at the rate of one every hour (Defenders of Wildlife) or 100 every day (National Wildlife Federation).

Why is extinction bad? It is sad to think that a pretty butterfly or a beautiful bird song will be gone for good, but why is it worth it to spend millions of dollars to try to protect against the loss of biodiversity?

•Well, first of all, humans are simply animals, too. We share the planet with lots of other animals, plants, bacteria, seaweed, mushrooms, and invisible one-celled organisms! We have no more of a "right" to the resources of the planet than any other species, yet in the past 100 years we have probably managed to wipe out more species than have been wiped out during the rest of the Earth's history! It's not right, it's not ethical. We should not kill off beautiful things to extinction.

•Secondly, even if you DO think that humans perhaps DO have more of a right to the planet, consider where all of the things we need to live comes from...? Our food consists of plants and animals. And those plants and animals usually need other plants and animals to live themselves! Much of our clothing (cotton, wool) comes from plants and animals. Much of our shelter comes from plants (wood). Much of our energy comes from plants and animals (wood for burning, fossil fuels). Dyes, perfumes, spices, milk, coffee, tea, bread, beer, and wine come from plants and animals. And drugs, valuable, life-saving drugs come from plants and animals - think of it! We're wiping out plants right now, completely, that may contain the secret to the cure for influenza or malaria or AIDS. For example, Taxol is a kind of drug very effective against certain kinds of cancer that comes from the Pacific Yew tree - a tree that is highly endangered right now.

•Third, the extent of our destructive effects on the planet's species is being seen now, and will be continued to be seen more and more in things like loss of topsoil, interruption of mineral cycles (minerals are things like phosphorus and carbon) which are critical to maintenance of all life on the planet, and damage to major bodies of water. Consequences from serious damage to things like this can effect the hole in the ozone layer in the atmosphere, the greenhouse effect - even cause a world-wide rise in sea level!

Many national and international efforts exist to help protect biodiversity. In this country, for example, we have such legislation as The Endangered Species Act, which helps to protect plants and animals that have been identified as threatened or endangered. Several federal and private organizations also exist to help protect biodiversity, including the U. S. National Fish and Wildlife Service, The Nature Conservancy, Defenders of Wildlife (which has a great endangered species primer, The Sierra Club, and the National Wildlife Federation, among others. In your own state, you have the Illinois Department of Natural Resources, through which you can assist local conservation efforts. All of these agencies have special programs or information for kids! The more informed and involved you can get now, the better!

The very best of luck to you! Thanks for writing to MadSci Network!

Kelleen Flaherty,

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