![]() Sponges were next, followed by the diversification of all other animals, including the lineage leading to humans.Īlthough the researchers determined that the ctenophore lineage branched off before sponges, both groups of animals have continued to evolve from their common ancestor. In a new study published this week in the journal Nature, researchers use a novel approach based on chromosome structure to come up with a definitive answer: Comb jellies, or ctenophores (teen'-a-fores), were the first lineage to branch off from the animal tree. Searching among today's most primitive-looking animals for the earliest branch of the animal tree of life, scientists gradually narrowed the possibilities down to two groups: sponges, which spend their entire adult lives in one spot, filtering food from seawater and comb jellies, voracious predators that oar their way through the world's oceans in search of food. ![]() view moreĬredit: Monterey Bay Aquarium Research Instituteįor more than a century, biologists have wondered what the earliest animals were like when they first arose in the ancient oceans over half a billion years ago. This specimen was observed on 2016 by MBARI’s remotely operated vehicle (ROV) Doc Ricketts in the Monterey Canyon at a depth of approximately 280 meters. Ctenophores have eight sets of cilia running down their side, which they use to propel themselves through the oceans in search of food. Image: Hormiphora californensis, called the California sea gooseberry, is a comb jelly, or ctenophore, common in California coastal waters.
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