One shrimp-like species may outweigh humanity's entire biomass

Antarctic krill, Euphausia superba, swarm in numbers so vast that scientists estimate their total biomass at up to 500 million tonnes, among the largest of any wild animal species on Earth. Nearly the entire Southern Ocean food web, from fish to penguins to whales, runs on krill, making a creature barely six centimetres long one of the most ecologically important animals on the planet.

— Wikipedia contributors, Antarctic krill — Euphausia superba