Tag: earthworms

Biodiversity restated: > 99.9% of global species in Soil Biota

Soil’s vast biodiversity is under severe threat from topsoil erosion and poisoning, potentially leading to widespread extinctions.

More than 99.9% of global species diversity is found within soils, according to a new review paper published in ZooKeys.

Comparing different studies on soil biota, author Robert J. Blakemore challenges previous estimates, which suggested a much lower proportion of life in soils. “Most life is found in Soil and most is microbial, affected by the current mass extinction event having profound effects influencing all evolution on Earth,” he says.


From the review paper: “Micro monde” progressions with microbial proportions greatly increased from Blakemore after Larsen et al.

“Soil filters and stores freshwater stocks (being subject to Earth tides!) and, as well as ~ 99% of human food, it provides most building materials plus many of our essential medicines/antibiotics. Thus, an important metric must be the scope and snapshot status of living or dormant Soil biota.”

One of the most recent estimates suggests that the soil realm is home to approximately 2.1 x 1024 taxa, which is thought to be more than 99.9% of global species biodiversity, mainly comprised of bacteria and other microbes.

The more you look, the more you find (lhs, pin-head after SCIENCE 2002; rhs, Bacteria on a pin tip courtesy Dr Kateryna Kon of Kharkiv National Medical University).

“Soil also supplies >99.7% of calorific food (just 0.3% from ocean plus 0.3% from aquaculture mostly fed with farmed stockfeed); with just about 6% total global protein from all fish; soil filters and stores most freshwater and is thus responsible for hydrological-recycle rainfall on land,” Blakemore says.

“My other paper last year on Biomass shows Soil houses >99% of organic carbon and it is the loss of this vital resources that is the greatest contributor to atmospheric carbon increase, despite the ‘greening’ effect on land.”

Blakemore, R. J. (2024). Biomass Refined: 99% of Organic Carbon in Soils. Biomass, 4(4), 1257-1300. https://doi.org/10.3390/biomass4040070.

However, this immense biodiversity is under threat. “Soil erosion is one of our greatest global issues of concern, and one of the most ignored. Droughts, floods, deserts, poisoning, capping and so on are affecting all soils and, due to this massive soil loss, plants are incapable of thriving. At the same time deforestation continues, mainly clearing for cattle pastures or soy fields to feed CAFO cows (or other stock),” the author says.

The loss of soil biodiversity has far-reaching consequences, leading to ecosystem degradation, reduced food production, and loss of potentially valuable resources, such as sources of medicines and antibiotics. Furthermore, soil loss inevitably results in silent species loss, mostly of microbes that are most dominant in soils, but also of more obvious soil macrobes, and specifically of earthworms, which are vital for soil health.

Around 7,000 ‘true’ earthworm species have been described, but estimates suggest the total number of earthworm species may be closer to 30,000-35,000 globally. “Due to their high endemicity and Soil’s heterogeneity, their unknowns are legion,” the author notes in his paper.

From the review paper: Global Soil Biodiversity Atlas (GBIF 2016) reporting ~ 667,000 soil biota or just about one third of known 2 million). Note that earthworms have 7,000 known and > 30,000 estimated species. Bacteria had 15,000 known species but estimated over one million (< 1.5% described). However, when microbes (excluding viruses) are properly considered and counted, as herein, soil unknowns are much higher (likely just < 0.0001% known at best). Vascular plants add ~ 400,000 species (cf. Anthony et al. 2023 with 466,000 angiosperm “Plantae”).

Earthworms enhance microbial activity, improve soil structure, and promote plant growth, which is why Blakemore suggests that “a simple solution to soil degradation is to attempt, in any way and at all times, to preserve and enhance earthworm populations.”

“Healthy soils are carbon-rich, hugely biodiverse and are a massive sponge for water – neither flooding nor drying during climatic extremes,” the author says, a reminder that healthy soils are not only vital for maintaining biodiversity, but also indispensable in supporting essential functions of planet and human survival.

“Due to the most pressing problem of topsoil erosion and irreversible extinction losses, a major shift should be realizing the overwhelming importance and fragility of our precious Soil,” Robert Blakemore writes in his paper.

Calling for a change in attitudes and funding to recognise the true scope of soil biodiversity, he encourages the formation of a dedicated Soil Ecology Institute that would catalogue, research and reverse the mass degradation of our planet’s most crucial, yet most neglected ecosystem – that of the Soil Realm.

References:

Blakemore RJ (2025) Biodiversity restated: > 99.9% of global species in Soil Biota. ZooKeys 1224: 283-316. https://doi.org/10.3897/zookeys.1224.131153

Blakemore, R. J. (2024). Biomass Refined: 99% of Organic Carbon in Soils. Biomass, 4(4), 1257-1300. https://doi.org/10.3390/biomass4040070.

Blog post on the topic by Robert J. Blakemore: https://vermecology.wordpress.com/2025/02/10/tandc

The Western Ghats of India revealed two new primitive species of earthworm

The Western Ghats mountains lie at the southwestern continental margin of Peninsular India and extend all the way from Gujarat to Kerala. The massif has earned its place amongst the eight ‘hottest’ biodiversity hotspots in the world.

There is a great variety of vegetation types which, coupled with the high rainfall and the moderate yearly temperature in the Western Ghats, provide many different habitats. Therefore, the mountains an area rich in earthworm, as well as amphibian and reptile diversity.

The two new species, named Drawida polydiverticulata and Drawida thomasi, have been discovered in the Western Ghats mountain ranges in Kerala by scientists Dr. S. Prasanth Narayanan, Mr. S. Sathrumithra, Dr. G. Christopher, all affiliated with Mahatma Gandhi University and Dr. J.M. Julka of the Shoolini University, India. They belong to the primitive family Moniligastridae. The species are described in the open access journal ZooKeys.

The new earthworms are distinguished by a set of characters. For one of them – Drawida polydiverticulata – there were peculiar features which determined its species name (polydiverticulata). It turned out that its multiple lobes, also called diverticulums, an organ located in the front of its body, are unique amongst the members of the genus. This species was found to be widespread in the protected shola grasslands of the Munnar region, including Eravikulam National Park, Pampadun Shola National Park and Chinnar Wildlife Sanctuary.

The second new earthworm, Drawida thomasi, was collected at the Kozhippara Waterfalls near Kakkadampoyil, at the border between Malappuram and Kozhikode. The species name (thomasi) is a tribute to Prof. (Dr.) A.P. Thomas, the Director of the Advanced Centre of Environmental Studies and Sustainable Development (ACESSD), Mahatma Gandhi University, “who initiated the taxonomical studies on the earthworms in Kerala after being at a standstill for almost a century.”

In addition to the new species, the scientists also report the occurrence of five species of the same genus that have not previously been recorded from the state.

To date, there are 73 species of the genus Drawida confirmed to be living in the Indian subcontinent. However, the greatest concentration (43 species) is found in the Western Ghats. The genus has an important centre of speciation in the southernmost state of Kerala.

Prior to this study, there had been sixteen Drawida species known from the state with ten of them being unique. The present discovery of two new species and five new local records further contributes to the vast species richness of the genus in the state.

At present, there are about 200 species known in the genus Drawida. Their habitats are spread across India throughout the Indochina region to southeastern Asia and up to the north in Japan.

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Original source:

Narayanan SP, Sathrumithra S, Christopher G, Julka JM (2017) New species and new records of earthworms of the genus Drawida from Kerala part of the Western Ghats biodiversity hotspot, India (Oligochaeta, Moniligastridae). ZooKeys 691: 1-18. https://doi.org/10.3897/zookeys.691.13174

Conservation and nameless earthworms: Assessors in the dark?

Species that live exclusively in a single region are at a particular risk of extinction. However, for them to be protected, thorough assessments of the environmental impacts need to be performed.

There are more than 100 earthworm species living in the soil and dead wood of KwaZulu-Natal Province, South Africa. Most of them live exclusively in small regions in the province, which makes them extremely vulnerable.

To scientists Dr Adrian J. Armstrong, Ezemvelo KZN Wildlife, and Ms Thembeka Nxele, KwaZulu-Natal Museum, the problem is twofold. Firstly, they note that the expression “out of sight, out of mind” is very suitable for the case of the endemic earthworms in South Africa. Secondly, they point out that the lack of common names for these species is a stumbling block that hinders their inclusion in conservation assessments.

As a result, the researchers try to rectify this situation by assigning standardised English names to the endemic earthworms in KwaZulu-Natal. Their article is published in the open access journal African Invertebrates.

Scientific names are often intractable to non-specialists, and the lack of common names leaves environmental assessors in the dark when they need to figure out which earthworms may occur at a development site. In the meantime, it has been found that about 50% of the native vegetation in KwaZulu-Natal has already been removed as a result of infrastructure construction and the figure is rising.

“The indigenous earthworms generally don’t survive in developed areas,” say the authors.

For instance, the informal use of an English name (green giant wrinkled earthworm) for the species Microchaetus papillatus, has facilitated the inclusion of this species in environmental impact assessments in KwaZulu-Natal.

While the green giant wrinkled earthworm does occur in a relatively large and rapidly developing area in KwaZulu-Natal, other species live in smaller areas that have been urbanised even more.

The extinction of these earthworms is not only undesirable from the point of view of biodiversity advocates – the role of this group of soil organisms is impossible to replace fully with non-native earthworms. For example, some of the large indigenous earthworms (more than 1 m in length) burrow much deeper than the non-native species, thereby enriching and aerating the soil at greater depth.

The authors are hopeful that by giving the indigenous earthworms in KwaZulu-Natal common names, the threatened and endemic species will be conserved through inclusion in environmental impact assessments. Furthermore, they believe that earthworms could draw attention to the areas where they occur whenever a choice for new protected areas is to be made.

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Original source:

Armstrong AJ, Nxele TC (2017) English names of the megadrile earthworms (Oligochaeta) of KwaZulu-Natal. African Invertebrates 58(2): 11-20. https://doi.org/10.3897/AfrInvertebr.58.13226