New research hints that comb jelly may be Earth's oldest animal

According to a recent study published in Nature, researchers think they may have discovered the first species to have walked the Earth 700 million years ago.

According to a press release from the University of California Berkeley, scientists concluded that the first animal was probably a comb jelly, or ctenophore – a predator that scours the water for prey.

Comb jellies, although looking like jellyfish, are quite different from them and move through the water on their cilia rather than their tentacles. They may be found in seas all around the world and are still a vital component of the marine ecology.

"All living things share a recent common ancestor that existed around 600 to 700 million years ago. Because they were soft-bodied and didn't leave a direct fossil record, it's difficult to tell what they were like, according to co-author of the research and UC Berkeley professor Daniel Rokhsar. But we can find out about our shared ancestry by making similarities between live species.

The question of whether the sponge or the ctenophore evolved first has been debated for a long time, according to the university. The majority of their lives are spent in one location, as sponges filter water via their pores to gather food particles.

Many have suggested that the sponge emerged first — before the ctenophore — because of its basic traits, according to experts. While sponges arrived first, according to this new research, ctenophores probably came second.

Scientists examined how the genes were arranged in the creatures' chromosomes to come to that conclusion. The chromosomes of the ctenophore differ significantly from those of sponges, jellyfish, and other invertebrates, indicating to scientists that the ctenophore may have evolved much earlier or much later than the others.

"At first, we couldn't tell if ctenophore chromosomes were different from those of other animals simply because they'd just changed a lot over hundreds of millions of years," Rokhsar said in the press release. The third possibility is that they diverged first, before any other animal lineages, and as a result are unique. We have to resolve the issue.

When scientists compared the chromosomes of ctenophores to non-animals, it was the "smoking gun" for them.

According to a news release, the team's analysis of the chromosomes of these various animals and non-animals revealed that while ctenophores and non-animals shared specific gene-chromosome combinations, sponges and other animals' chromosomes were rearranged in a totally different way.

Researchers claim that the new understanding is important for understanding the foundational behaviors of all animals and humans today, including how we move, consume, and detect our immediate environment.