The presence of life on Earth is ever changing and while many other species have come and gone, jellyfish have remained present for hundreds of millions of years. So, where did jellyfish come from?
Taxonomy is the study of the classification of organisms and is a starting place for understanding where jellyfish came from. An example of classification is the moon jellyfish:
Kingdom-ex. Animalia (animals)
Phylum-ex. Cnidaria (stinging cells present)
Class-ex. Scyphozoa (jellyfish)
Order-ex. Semaeostomaea (having oral arms)
Family-ex. Ulmaridae (branched structural canals in bell of jellyfish)
Genus-ex. Aurelia (moon jellyfish)
Species-ex. aurita (moon jellyfish)
The evolution of jellyfish began as a small, crude, organism called a prokaryote. Through millions of years of evolution, prokaryotes eventually became eukaryotes, which possess membrane bound organelles. Eukaryotes developed into multicellular organisms of the kingdom Animalia. Small organisms began to develop stinging cells, called cnidocytes, to capture their prey. This separated them from other species bringing about the classification of phylum Cnidaria. The phylum Cnidaria is composed of the classes Medusozoa (jellyfish) and Anthozoa (sea anemones and corals). These animals are spineless and brainless, but somehow have managed to thrive when other species went extinct.
Jellyfish taxonomy can further be broken down into the class Hydrozoa (ex. Portugues man o’war), the Cubozoa (ex. box jellyfish), the Staurozoa (ex. stalked jellyfish), and the Scyphozoa (ex. moon jellyfish). All these species use cnidocytes (stinging cells) to capture their prey,have a polyp life stage (a small anemone like organism that attaches to rocks, docks, etc) and a medusa (the jelly like, bell shape, commonly seen) life stage.
A wild moon jellyfish. Photo credit: STERLING ZUMBRUNN