The Biomass Leaderboard
Ranking the animal species that outweigh all the rest.
Introduction
When we think about the most abundant animals on Earth, our minds often go to ants, fish, or insects. But when we measure biomass—the total mass of living members of a species—the results reveal an unexpected dominance by a few highly influential species, many of which are linked directly to human activity. This post ranks the top 10 individual animal species by their estimated global biomass, expressed in wet mass.
The Rankings
1. Cattle (Bos taurus)
~400 million tonnes wet mass
Domesticated cattle are the heavyweight champions of animal biomass. Their vast numbers, driven by the global beef and dairy industries, have reshaped ecosystems and contributed significantly to greenhouse gas emissions.
2. Antarctic Krill (Euphausia superba)
~379 million tonnes wet mass
These small, shrimp-like crustaceans form the foundation of the Southern Ocean food web, feeding whales, seals, penguins, and countless fish species. Their sheer abundance makes them one of the largest biomass contributors on the planet.
3. Humans (Homo sapiens)
~373 million tonnes wet mass
Our own species rivals Antarctic krill in biomass. With over 8 billion individuals, humans have transformed the biosphere and redirected biomass flows through domestication, agriculture, and industrial activity.
4. Domestic Pigs (Sus scrofa domesticus)
~40 million tonnes wet mass
Pigs are one of the most common sources of meat globally. Their numbers are concentrated in industrial farming operations, making them a dominant contributor to terrestrial animal biomass.
5. Domestic Dogs (Canis lupus familiaris)
~20 million tonnes wet mass
Beyond livestock, dogs are the most numerous large carnivores on Earth, living both as pets and in feral populations.
6. Domestic Cats (Felis catus)
~2 million tonnes wet mass
Cats, beloved companions and skilled predators, are found on every continent except Antarctica. Their biomass reflects their ubiquity in human settlements.
7–10. Data Gap
Reliable, species-specific biomass estimates for additional individual species beyond cats are scarce. Many large biomass contributors—such as various fish, insect, and wild mammal species—are aggregated into broad taxonomic groups in ecological surveys, making precise rankings impossible without speculative extrapolation.
Observations
Domestication Dominance: Five of the top six species are domesticated animals. Human demand for food, labor, and companionship has created massive populations that would not exist in natural ecosystems.
Marine Powerhouses: Antarctic krill demonstrate that tiny organisms can achieve staggering biomass when their ecological niche is vast and productive.
Humans as a Biomass Force: Our presence on this list is both a testament to our evolutionary success and a reminder of our ecological footprint.
Conclusion
The biomass leaderboard is shaped as much by human influence as by natural productivity. While krill and other marine organisms still hold their place, the overwhelming presence of domesticated species underscores how agriculture and domestication have restructured Earth’s living mass. Closing the data gaps for the next four species in this top 10 would require more precise, species-level biomass studies—especially for wild fish and invertebrates.