A recent study suggests that despite hundreds of years worth of scientific research dedicated to identifying our planet’s species, only 14% of them have been cataloged. The study predicts that Earth is home to 8.7 million species, only 1.2 million of which are currently known to scientists.
The study was conducted to determine how close scientists are to identifying and cataloging all of Earth’s species. The findings of the study have confirmed that “we are way off” from becoming familiar with every species, says Boris Worm, a co-author of the study.
Worm has noted that several classes of living things, such as mammals and birds, are close to being completely identified. Other classes, however, such as fungi, are still a long way from being completely identified. The study mentions that only seven percent of the world’s fungi have been identified, and less than 10% of the ocean’s life forms have been identified.
The extensive knowledge of mammals and other prominent life forms is due in large part to the physical characteristics they possess. In the study, Worm notes that life forms that are “conspicuous” and “relatively large” have been identified primarily because they are “easy to find”; conversely, microscopic forms of life such as fungi are much harder to identify. The ocean’s life forms present another challenge, as the study of the depths of the ocean is much more difficult to conduct than the study of life on land.
Before this most recent study was published, many other attempts have been made to predict the amount of species living on Earth. Previous estimates have ranged between three million and one hundred million species. Of the 8.7 million species currently estimated, Worm states that “there is an age of discovery ahead of us when we could find out so much more of what lives with us on this planet.”
To determine the percentage of undiscovered species, the authors of the study had to group species into several different categories. First, similar species were divided into a group known as a genus, then were divided into a broader group known as a family. The subdivisions are, in order: genera, families, order, classes, and phyla. Broader groupings continued until all species were divided into one of five kingdoms- animals, plants, fungi, chromists, and protozoa. Then, using statistics derived from the groupings, researchers were able to predict the number of species on Earth. The method used to determine the number of species is called linear regression.
One of the most difficult part of the study is dealing with the rate of extinction that continues to wipe out species at an alarming rate. Worm stated that rates of extinction have climbed to ten to a hundred times their natural level, which challenges the process of identifying new species. Worm described the process as discovering “nature’s library, and we’ve only begun to decipher the first ten books…we’re throwing out entire books without having a look at them.”
The study has drawn criticism from some researchers, who have called the study unreliable. Critics of the study have noted that instead of using linear regression to determine the amount of species, the authors of the study should have used a different technique called ordinal regression. Using ordinal regression, critics say, would have provided a much more accurate number, which could have been either much higher or much lower than 8.7 million.
The results of the study have indicated that it is crucial to continue to study and discover new species so that we might get a better look at the biodiversity of the planet. With the current rate of extinction, however, species are being wiped out even before they are discovered, highlighting the importance of preserving our environment before even more species have gone extinct.
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