The Smallest Known Animals on Earth

Myxozoans are microscopic parasites that hold the record for the smallest animals ever discovered. While they belong to the same family as jellyfish, they have evolved into tiny, simplified forms that are invisible to the naked eye.

These fascinating creatures often cycle between fish and small aquatic worms to survive. Because they evolved from complex ancestors, they have essentially discarded most of their animal traits over millions of years. Scientists once confused them for single-celled organisms before realizing they were actually complex multicellular animals. They prove that evolution does not always lead to becoming bigger or more complicated.