Oldest AnimalWorld's Oldest Animal Discovered: Meet the Palm-Sized Sea Creature

   World’s Oldest Animal Discovered: Meet the Palm-Sized Sea Creature ,Scientists have long believed that the humble sea sponge, an animal that feeds by filtering water through itself, formed the oldest group of animals on earth. But a a new study argues that the type of comb jelly is actually older and carries genetic material from distant, non-animal ancestors.

Ciliated jellyfish, which look like miniature jellyfish, use rows of cilia to swim through the ocean and grab prey with tentacles that release a sticky mucus-like substance. Like other animals, they meet the standard of having evolved from a fertilized egg into a multicellular organism.

Early labor and the smoking gun

To determine whether comb jellies or fungi branch off the animal family tree first, researchers at the University of California-Berkeley and the University of Vienna attempted genetic analysis, but their initial attempts led nowhere thanks to the extreme ages of each group.

Next, they turned to chromosomes, specifically the arrangement of genes on each chromosome, hoping to trace patterns over time. After they determined the chromosomal structure of Hormiphora californiana type of jelly comb, they could see things more clearly: the jelly comb had a unique arrangement that resembled non-animals, while the sponge was in line with other animals.

Read more: Meet 8 of the longest living species in the world

“That was the smoking gun,” said Daniel Rochsar, a biologist at the University of California, Berkeley and one of the study’s authors, in press release.

Jellies combs branched first, before animal chromosomes changed on a large scale. This meant that the jelly-like crest arrangement represented “a relic of a very ancient chromosomal signal,” says Rochsar. “It took a bit of statistical detective work to convince us that this was indeed a clear signal and not just random noise.”

The results could lay the groundwork for new studies of how animal muscles and other organs evolved, and the methodology could prove useful in other fields, Darin Schultz, a biologist and one of the study’s authors, said in a press release. “We have developed a new way to take one of the deepest possible looks at the origins of animal life.”

The ancient ancestor of all animals

While the crested jelly lineage is the oldest still in existence, stretching back to at least 500 million years ago, even older animals existed around 600 to 700 million years ago and have passed down genetic material to the present day.

“It’s hard to know what they were like because they were soft-bodied animals and left no direct fossil record,” says Rohsar. “But we can use comparisons between living animals to learn about our common ancestors.”

How simple can an animal be?

The ocean is full of simple animals like sea sponges, scallops, jellyfish and sea anemones that have no defined brain, the researchers say, if not muscles and nerves.

Mushrooms they don’t have a nervous system, they don’t have muscles, and they look a bit like colonial versions of some single-celled protozoa,” says Rohsar.

After the larval stage, in which they swim in a flower bulb-like form, they settle in one place and rarely leave. From that moment on, they subsist on whatever particles of food they catch in their pores.

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