The process of describing this species (Pristimantis bambu) took two years since the specimen was first collected.
Credit: Alejandro Arteaga
EDINBURGH: Estimates of the total number of species on Earth have been narrowed to 8.7 million. Until now, the best estimates were somewhere between 3 and 100 million.
A new study has estimated there to be 6.5 million species on land and 2.2 million (about 25% of the total) dwelling in the ocean depths. With a staggering 86% of all species on land, and 91% of those in the seas yet to be discovered, researchers have called for greater public involvement to help fill this massive gap in our knowledge of the planet.
"With the clock of extinction now ticking faster for many species, I believe speeding the inventory of Earth's species merits high scientific and societal priority," said lead author Camilo Mora of the University of Hawaii and Dalhousie University in Halifax, Canada of the paper published today in PLoS Biology.
"Renewed interest in further exploration and taxonomy could allow us to fully answer this most basic question: What lives on Earth?"
The Taxonomic Pyramid
In 1758, Swedish scientist Carl Linnaeus created and published the system still used to formally name and describe species. In the 253 years since, about 1.2 million species (roughly one million on land and 250,000 in the oceans) have been described and entered into central databases.
By using this information, to date, the best estimates of Earth's species total was based on educated guesses and opinions of experts, who variously pegged the figure in a range from 3 to 100 million - with no way to validate their estimates.
For this new estimate of 8.7 million (give or take 1.3 million), the scientists used an innovative approach taking advantage of the way taxonomists classify new animals. Each species belongs to a larger group called a genus, which belongs to a larger group called a family, and so on. We humans, for example, belong to the class of mammals, along with about 5,500 other species.
Much like the layers of a pyramid, there are fewer high level groups than lower level groups. By analysing the taxonomic clustering of the 1.2 million species already classified in the comprehensive and peer-reviewed Catalogue of Life and the World Register of Marine Species, the researchers discovered reliable relationships between the numbers of the more complete data of higher taxonomic levels and the species level. In the same way that it is possible to predict the size of the bottom layer of a pyramid using the information from the other layers - they were able to predict the missing information to form the estimate.
A call to action
With this new estimate - predicting only around 14% of Earth's and 9% of the ocean's species documented - scientists are calling for an increased effort in cataloging the animals that live around us from both the scientific community and the public.
Brian Fisher of The California Academy of Science, who was not involved in the study, said, "For me this paper is a call to action. With this estimate, I find it amazing that the public seems more interested in finding life on Mars than in their own backyard. The real adventure is right here back on Earth. We need more taxonomists."
Fisher added, "We need to be faster, more holistic, and make sure we don't hide our results in print only, unread publications. We need to democratise taxonomy and find a way to increase collaboration and public involvement in the discovery process. We will never uncover all species on earth, but we need to do a lot better than 14%."
Help from the Public -- how?
I imagine a large number of people would be keen to help. However, how is the layman to know whether a creature they have found is 'known' or not? While the list of known species may be small compared to 8.7million, it is still large enough that the vast majority of creatures one would usually encounter are well known. One could capture every creature he encounters, and send it to a specialist, but that isn't very helpful.
I think web based software may be the answer. For example, enter some basic key words and characteristics describing a creature, and search a database for matches (obviously google already does this, but with a database of known species specifically written for this purpose, it's accuracy and useability would be improved imeasurably).
Even better would be to include image recognition software within the search....
Sounds like quite a daunting project.