http://www.ck12.org Chapter 4. Understanding Biodiversity: An Introduction
Millions of Unseen Species
A study released in August 2011 estimates that Earth has almost 8.8 million animal, plant, and fungi species, but
we’ve only discovered less than a quarter of them. Recent newly discovered species have been very diverse: a
psychedelic frogfish, a lizard the size of a dime, and even a blind hairy mini-lobster at the bottom of the ocean.
There are potential benefits from these undiscovered species, which need to be found before they disappear from the
planet. The study estimates that of the 8.8 million species, about 6.5 million would live on land and 2.2 million in the
ocean. The research estimates there are 7.8 million animal species, followed by fungi with 611,000 and plants with
just shy of 300,000 species. See http://news.yahoo.com/wild-world-millions-unseen-species-fill-earth-210051661.ht
ml for additional information.
If the 8.8 million estimate is correct, “those are brutal numbers,” said Encyclopedia of Life executive director Erick
Mata. “We could spend the next 400 or 500 years trying to document the species that actually inhabit our planet.”
Biodiversity and Human Actions
Over 99 percent of all species that ever lived on Earth have gone extinct. Five mass extinctions are recorded in the
fossil record. They were caused by major geologic and climatic events. Evidence shows that asixth mass extinction
is occurring now. Unlike previous mass extinctions, the sixth extinction is due to human actions.
Some scientists consider the sixth extinction to have begun with early hominids during the Pleistocene. They are
blamed for over-killing big mammals such as mammoths. Since then, human actions have had an ever greater impact
on other species. The present rate of extinction is between 100 and 100,000 species per year. In 100 years, we could
lose more than half of Earth’s remaining species.
Causes of Extinction