The First Animals on Earth was Jellyfish not Sponges

Scientists had considered the humble sponge to be the oldest ancestor of all living creatures on Earth. However, in a new study, scientists suggest that marine jellyfish are apparently the first animals to exist on the planet.

In this discovery, researchers from Vanderbilt University and the Wisconsin-Madison University have carried out a new type of genetic analysis that involves ctenophores or marine jellies as the sister group to all other metazoans. This also means that this new study was able to collect a massive amount of genetic data that supports marine jellies in a new, plausible family tree.

According to Antonis Rokas from the Department of Biological Sciences at Vanderbilt, this type of analysis worked out for 95 percent of cases, however, there are irreconcilable differences in the remaining five percent. The team focused on examining the gene sequences of different organisms to identify their closest relatives, examining hundreds of thousands of genes.

Their results revealed a "phylogenetic signal" that determined comb jellies over sponges since they possess more supportive genes that are also present in sponges. This phylogenetic method was also used to determine if crocodiles are more closely related to turtles or birds. Their results revealed that turtles and crocodiles have 74 percent shared genes and are now considered as a sister species, while birds are considered as close cousins of crocs.

Researchers say that not all cases are solved, such as the origins of modern birds and flowering plants. This is caused by a single "opinionated" gene that suggests that these species evolved too fast and did not leave enough genetic remnants from their original ancestors.

"Our new approach can help resolve many long-standing genetic controversies by using this phylogenetic reconstruction in another level," Rokas said.

This new study is published in the journal Nature Ecology & Evolution.