There Might Be 1 Trillion Species on Earth
Researchers have attempted to use the laws of math to make an estimate of species that includes both micro and macro life.
Calculating how many species exist on Earth is a tough challenge. Researchers aren't even sure how many land animals are out there, much less the numbers for plants, fungi or the most uncountable group of all: microbes.
Now, researchers have attempted to use the laws of math to make an estimate that includes both micro and macro life. The researchers estimated that there may be as many as 1 trillion species out there.
The research is based on scaling laws, which predict a proportional change linking two variables. For example, scaling laws apply to the change in metabolic rates as body size changes, and to the number of species found by geographical area. [Biodiversity Abounds: Stunning Photos of the Amazon]
Indiana University researchers Kenneth Locey and Jay Lennon analyzed data sources that sampled 20,376 sites for bacteria, archaea and microscopic fungi, and 14,862 sites for trees, birds and mammals. Using the total abundance of individuals, the researchers were able to work out the scaling rules that linked the number of individual organisms to the number of total species.
The method led to an estimate of between 100,000,000,000 (that's 100 billion) and 1,000,000,000,000 (that's a trillion) species of microbes on Earth.
"Until now, we haven't known whether aspects of biodiversity scale with something as simple as the abundance of organisms," Locey said in a statement. "As it turns out, the relationships are not only simple but powerful, resulting in the estimate of upwards of 1 trillion species."
It has been estimated that there are 100 trillion individual bacterial cells in a single human body, and a nonillion (10^30) individual bacterial and archaeal cells on Earth, the researchers wrote Monday (May 2) in the journal Proceedings of the National Academy of Sciences. If these individuals represent a trillion or so species, that means very little is known about Earth's microscopic denizens, Lennon said in the statement. The genomes of only 100,000 microbial species have been sequenced, and only about 10,000 species have been grown in a lab, he said.
"Our results show that this leaves 100,000 times more microorganisms awaiting discovery - and 100 million to be fully explored," Lennon said.
Pinning down exact numbers of microbial species is tricky, however. Previous estimates have pegged the number at between 10 million and a billion, according to a 2004 review paper in the journal Microbiology and Molecular Biology Reviews. A 2011 paper in the journal PLOS Biology put the total number of species at 8.7 million, but that study's methodology calculated the existence of only 10,000 bacterial species, a contradiction of the 2004 review that put the minimum known bacterial species above 35,000.
And it's not just bacteria that are the problem. Even estimates of nonmicrobial species vary wildly. Researchers reported in 2014 in the journal Trends in Ecology & Evolution that estimates of the number of species on the planet have "failed to converge over more than six decades of research." The estimates range from 0.5 million to 10 million and are often logically inconsistent, the authors of that 2014 study wrote: "For example, estimates of species richness for coral reefs have exceeded estimates for all marine species, and estimates for all marine species have exceeded global estimates for all realms combined."
On the other hand, a study published in the journal Science in 2013 suggested that where there's a will, there's a way: The authors said it would cost a mere $500 million to $1 billion a year for 50 years to describe most species on Earth.
More from LiveScience:
Gallery: Microbes Make Glowing Galaxies & Other Art Images: One-of-a-Kind Places on Earth Images: Colorful Corals of the Deep Barrier Reef Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Original article on Live Science.
Earth is home to gobs of species, from tiny to gargantuan, and ordinary to downright weird. Take this whimsical octopus spotted by NOAA Ship Okeanos Explorer's remotely operated vehicle.
The cocoa frog is one of six new frog species that were recently found in a rainforest-dominated mountainous region of southeastern Suriname. “At a time when so many frog species are declining and undergoing extinctions worldwide, it is particularly uplifting to discover so many new frogs in a single area,” Trond Larsen, a tropical ecologist and director of the Rapid Assessment Program at Conservation International, told Discovery News. He and his team found about 60 new species in the South American country.
The tiny Lilliputian beetle measures just 2.3 mm long and could be the smallest dung beetle in the entire Guiana Shield and among the smallest in the world. “Dung beetles act as a cleanup crew in the forest,” Larsen said. “By burying dung, they not only control parasites and disease, including those that affect people, but also disperse seeds and recycle nutrients that enable forest regeneration.”
Leeanne Alonso, director of Global Biodiversity Exploration for Global Wildlife Conservation, went on the expedition with Larsen. She thinks this beetle might be small and red to look like a seed stuck in poo, thereby fooling predators. “Dung beetles in forest areas are a good indicator of mammal diversity,” she added. Without mammals providing their food source, there would be few such insects.
The collection of new animals includes 11 species of fish that are probably new to science. “Small, brightly-colored tetras similar to this one are popular in the aquarium trade, and sustainable exports of wild species could provide financial support to local communities and incentives to conserve the species’ natural habitat,” Larsen said.
Alonso added that, as new species go, fish are relatively rare. “It’s amazing that so many were found in this region, which I believe has the world’s best and most beautiful and pristine forests in the world.” She loved it so much that she took her family there on a vacation after the research work ended.
Bats are another “good indicator of habitat quality,” Alonso said. She explained that, in this case, the bat thrives on fruit, so the region must support plenty of healthy fruit-producing trees.
Genuine coral snakes are highly venomous, but this false coral snake’s name is itself somewhat misleading, as the researchers found out the hard way. Alonso said that a helicopter pilot transporting the scientists was bitten by one. “His arm really swelled up,” she said, explaining that all such snakes have sharp teeth and venom, just not as poisonous as the “real” coral snake this species resembles.
This extraordinary new insect displays waxy fronds at the end of its body that was built for jumping among plants. “Maybe the fronds are meant to resemble anthers of a flower, helping with camouflage?” Alonso said, admitting that nature sometimes works in still-mysterious ways. She continued, “So little is known about insects from this region, so this was a real find.”
Top-level predatory big cats, such as this margay, are yet another sign of healthy habitat. More of them generally means there are more prey animals to feast upon. “Margays love to sleep and hide in caves at the site,” Alonso added.
Six new katydids, including this one, were discovered. Larsen described it as a “gangly species with oversized, spiny hind legs.” The newly discovered katydids "are indicative of the pristine, healthy forests of the Upper Palumeu Watershed," Larsen said, "and the forests in turn help to ensure continued flows of clean, plentiful water used by people throughout the rest of the country.”
“Despite their generally diminutive size, water beetles can be useful indicators of water quality, and also help to filter and keep water clean,” Larsen said. “Many of the 26 new water beetle species discovered on this survey are probably restricted to isolated habitats, especially in the mountains of southeastern Suriname, and may occur nowhere else.”
Eleven new fish species were found in the region, dubbed a "tropical Eden" by the researchers. Larsen said, “This new sucker-mouthed armored catfish was rare, and only encountered in the narrow, upper reaches of the Palumeu River.
“This delicate slender opossum is really cute,” Alonso said. “It’s hard to find small mammals like this, which are indicative of primary forest.”
is the largest of all South American dung beetles, Larsen shares. Despite its name, this species feeds more frequently on dead animals than on dung. A highly unusual case in the Animal Kingdom, both males and females of this species possess a long horn on their head, which they use during intense battles with other individuals of the same sex. The vast difference in adult body size seen here is primarily determined by how much food was available to the developing larva. This species is capable of rapidly burying large animal carcasses, providing an important ecological service that sustains rain forest health.
“Given the beautiful coloration, high visibility and popularity of frogs in the poison dart frog family (Dendrobatidae), most species in this group are relatively well known,” Larsen said. “Therefore, the discovery of this species potentially new to science is particularly exciting. The toxic secretions of poison dart frogs hold great potential to yield new medicines that could greatly benefit the world -- yet with frogs declining globally, their protection in the wild is essential.”
The researchers could have just scratched the new species surface in southeastern Suriname, given that other animals, fish, insects and more unknown to science could be found there. The region’s human population is currently small -- only about 500,000 -- but it’s growing and there is a threat of future habitat-destroying activities, such as mining and logging. Alonso hopes that the wilderness can be protected, with money-generating activities such as ecotourism allowing both humans and amimals to thrive there.