The Earliest Surviving Organism on Earth

Jellyfish-like comb jelly may be first multicellular animal on Earth

For the first time, researchers have found a powerful answer to the centuries-old mystery of the existence of a multicellular animal on Earth.

The Discovery

The jellyfish-like creature known as the comb jelly first appeared 700 million years ago – compared to dinosaurs born 230 million years ago. A team from the University of California at Berkeley set out to find out the relationship between the tree of life of animals in order to better understand the origin and evolution. The finds also put an end to the longstanding argument that sea sponges were the first animals, as their fossils are about 600 million years old.

The Close Relatives of the First Animals

The study found that ctenophores are the closest relatives of the first animals and can be found swimming in modern oceans and aquariums. Ctenophores have eight sets of tentacle-like cilia running down their sides, which they use to propel themselves across oceans, traveling over four miles below the surface.

Understanding Our Origins

Daniel Rohsar, professor at the University of California and study co-author, said: “The most recent common ancestor of all animals probably lived 600 or 700 million years ago. But we can use comparisons between living animals, to learn about our common ancestors. It’s exciting – we’re looking at Flashback where we have no hope of getting fossils, but by comparing genomes we learn something about early ancestors.”

Evolving Diversity of Animals

The evolutionary relationships between diverse beings—in particular, the order in which each lineage branches off from the main stem of the animal tree of life—is a matter of controversy. Together they are called bilaterians, they have a head with a central brain, intestines running from the mouth to the anus, muscles and other common features that had already developed by the time of the famous “Cambrian explosion” about 500 million years ago.

The Importance of Chromosomes

Researchers have previously shown that the chromosomes of sponges, jellyfish and many other invertebrates carry similar genes despite more than half a billion years of independent evolution. This discovery showed that the chromosomes of many animals evolve slowly and allowed the team to mathematically reconstruct the chromosomes of the common ancestor of these diverse animals.

The discovery of the comb jelly as the first multicellular animal on Earth sheds new light on the evolution of life on our planet. This will undoubtedly lead to further discoveries about our past and how we came to exist in the world today.

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