Best current estimates suggest there may be around ten sextillion animals alive on Earth at any time, spread across millions of species.
Why The Question “How Many Animals Are In The World?” Is Tricky
On the surface, “how many animals are in the world?” sounds like a simple counting problem. In practice, it turns into a huge estimation puzzle that stretches from backyard birds to deep sea worms and microscopic mites in the soil. The answer also changes with time, because births, deaths, seasons, and human activity all shift animal numbers every moment.
To make sense of global animal counts, researchers usually split the topic into three angles. First, they tally how many animal species exist. Second, they estimate how many individual animals those species contain. Third, they weigh total biomass, which sums the carbon stored in animal bodies. Each lens tells a different story about life on Earth.
How Many Animals Are in the World? Big Picture Numbers
When people ask how many animals are in the world, they usually want a single headline figure. A widely cited range suggests there could be up to ten sextillion wild animals on the planet at any moment, with at least ten trillion vertebrates such as mammals, birds, reptiles, amphibians, and fish. That upper value is written as 10^22, a one with twenty two zeros after it, and most of that total comes from tiny invertebrates.
Even within that range, uncertainty stays high. Soil animals, plankton, and deep sea creatures are hard to sample. Count methods often start from local surveys, then scale up across similar habitats. Small changes in those starting assumptions can swing global totals by many orders of magnitude, so any exact figure should be read as a rough guide instead of a final tally.
Approximate Animal Numbers By Group
The table below summarises some rough orders of magnitude that appear in current research, drawing on studies of wild vertebrates, soil arthropods, and other abundant groups. Values vary between papers, but the broad pattern stays the same: tiny animals dominate by count, while larger animals may dominate attention.
| Animal Group | Approximate Global Count | Main Source Of Uncertainty |
|---|---|---|
| All Wild Animals | Up to 10 sextillion individuals | Limited data for many habitats and tiny species |
| Wild Vertebrates | Roughly 100 billion to 100 trillion | Patchy monitoring of reptiles, amphibians, and small mammals |
| Soil Arthropods | Around 10 quintillion | Sampling depth, soil type, and climate differences |
| Nematodes | Likely above 10 quintillion | Microscopic size and hard to reach habitats |
| Wild Birds | Billions to low trillions | Under counted tropical and seabird populations |
| Wild Land Mammals | Hundreds of billions at most | Lack of data outside well studied regions |
| Farmed Animals | Tens of billions at any time | Variations between farming systems and seasons |
How Many Animal Species Do Scientists Know About?
Counting species is more straightforward than counting every individual, because each species only needs to be described once. Around one and a half million living animal species have formal names so far, including roughly one million insects and about sixty five thousand vertebrates. Many taxonomists work through museum collections and field samples that keep adding to this list every year.
Several research groups have tried to estimate the true total. One influential study suggested that there may be around 7.7 million animal species in all, far above the number that currently sit in databases. Another analysis that covered all forms of life, not just animals, placed the global total near 8.7 million species, with only about 1.2 million described. Either way, most animals that share the planet with us still lack formal names.
Data visualisations from projects such as Our World In Data on species counts show how uneven this work is. Insects dominate the charts, while many marine invertebrates, deep sea species, and microscopic animals remain underestimated. Thousands of new species appear in the scientific literature each year, even as others vanish through habitat loss and climate change.
Described Species Versus Undescribed Species
Described species are those with formal scientific names, type specimens, and published descriptions. Undescribed species still exist in forests, oceans, and soil, but no one has yet gone through the process of naming them. Genetic barcoding and automated image tools now speed up discovery, yet taxonomic work remains time consuming and under funded in many regions.
This gap means that species based counts of how many animals are in the world only capture part of reality. In groups such as mites, nematodes, and tiny crustaceans, described species may represent a small slice of the full total. For policy and conservation, researchers often work with higher level groups or habitat based models, since those are easier to track than millions of separate species.
Where Do Most Animals Live On Earth?
Animal life covers almost every part of the planet, but numbers are far from evenly spread. Oceans hold vast schools of fish, swarms of plankton, and jellies that drift through sunlit and dark waters. On land, insects, spiders, and other arthropods fill forests, grasslands, and cities. Below ground, worms and other tiny animals move through soil in layers that may be invisible from the surface.
A major study of global biomass published in the journal PNAS showed that arthropods, fish, and other invertebrates make up most animal mass on Earth, while mammals and birds contribute only a small share. That work, which assembled a wide census of life, also showed that livestock now outweigh wild mammals and birds by a large margin. You can see these patterns in charts from the life on Earth dataset that builds on the same research.
Habitats With The Highest Animal Counts
Oceans likely hold the largest share of animal biomass, especially when fish and marine invertebrates are included. Coastal zones, coral reefs, and upwelling areas support dense food webs, while deep sea regions host specialised species that often live at unusually low densities. Counting animals in these places demands nets, sonar, underwater cameras, and model based estimates.
Soil and leaf litter also hide huge numbers of small animals. Recent work on soil arthropods suggests that there may be around ten quintillion individuals worldwide, most of them mites and springtails. Nematodes, which live in both soil and aquatic habitats, may be even more numerous by count, while each individual weighs almost nothing.
How Scientists Estimate Global Animal Numbers
Scientists use a mix of field surveys, statistical models, and remote sensing to estimate global animal numbers. For larger animals such as birds and mammals, they often rely on sample plots, camera traps, acoustic recorders, and citizen science projects. Data from these sources feed into models that extend density estimates across wider ranges.
Limits And Uncertainties In Animal Counts
Even with advanced tools, estimates of how many animals are in the world come with wide uncertainty bands. Remote regions, such as deep oceans, polar seas, and dense tropical forests, still lack regular surveys. Many small or nocturnal species avoid standard detection methods. Climate shifts and land use change also alter ranges faster than monitoring programs can update maps.
These gaps lead researchers to present ranges and confidence intervals instead of single precise totals. For instance, estimates of wild land vertebrate numbers often span three orders of magnitude. Soil animal counts vary with moisture, season, and land management. Farmed animal numbers change in response to markets and disease outbreaks. Any global total is best read as a snapshot with fuzzy edges.
Rough Orders Of Magnitude For Animal Numbers
One way to handle these uncertainties is to think in orders of magnitude instead of exact integers. Instead of asking whether there are 9.8 or 10.2 sextillion animals, it helps to ask whether the true value likely sits closer to 10^21 or 10^22. The table below collects some of the ranges already mentioned and groups them by type of animal.
| Category | Estimated Scale | Notes |
|---|---|---|
| Total Wild Animals | 10^21 to 10^22 individuals | Mostly tiny invertebrates and plankton |
| Wild Land Vertebrates | 10^11 to 10^14 individuals | Includes mammals, birds, reptiles, and amphibians |
| Soil Arthropods | About 10^19 individuals | Based on global soil surveys and biomass data |
| Nematodes | Likely 10^19 to 10^21 individuals | Present in huge numbers in soil and aquatic sediments |
| Farmed Vertebrates | Tens of billions at a time | Dominated by chickens, pigs, and cattle |
| Described Animal Species | Around 1.5 million | Most are insects and other invertebrates |
| Estimated Animal Species | Roughly 7 to 9 million | Based on extrapolations from well studied groups |
Why Global Animal Numbers Matter
Asking how many animals are in the world is not only a trivia question. Global counts help conservation groups track trends, set targets, and judge whether protection efforts work. For instance, the WWF Living Planet Index uses time series data for vertebrate populations to show that average monitored wildlife populations have dropped sharply since 1970. That message depends on careful counting and comparison across decades.
Final Thoughts On Global Animal Numbers
No single number can fully answer the question “how many animals are in the world?”. The best that current science can offer is a range that likely sits somewhere around ten sextillion living animals, spread across millions of species and countless habitats. Tiny soil creatures and plankton dominate by count, while larger animals draw more human attention.
As data improve and new methods arrive, these estimates will shift for global context. Even now, researchers keep adding new species to the catalog and revising biomass figures. For readers, the main takeaway is scale. Life on Earth is far more abundant and varied than day to day experience suggests, and every estimate of global animal numbers hints at that depth of diversity.