It evolved from the same primordial animals as humans did.
These creatures have been around for 700 million years. Image credit: Alexander Semenov
If you were asked to name the oldest living creature on Earth, what would you say? A turtle? A whale? A tree? Well, you might be surprised to learn that the answer is none of these. According to a recent study by scientists from the University of California, Berkeley, the oldest living creature on our planet is a jellyfish-like organism called a ctenophore, also known as a comb jelly.
Ctenophores are not actually jellyfish, but they belong to a different group of animals that have eight sets of cilia, or hair-like structures, that they use to swim and feed in the ocean. They are also bioluminescent, meaning they can produce light from their bodies. Some of them can even regenerate parts of their body if they are injured.
Ctenophores are bioluminescent and some can even regenerate their bodies. Image credit: Orin Zebest
Ctenophores have been around for a very long time, up to 700 million years ago, according to the study. That’s much longer than the dinosaurs, which appeared only 230 million years ago, and even longer than the sponges, which were previously thought to be the oldest living animals with fossils dating back about 600 million years.
How did the scientists figure out that ctenophores are the oldest living creatures? They used a technique called comparative genomics, which involves analyzing the DNA sequences of different animals and looking for similarities and differences. By comparing the genomes of ctenophores with those of other animals, including sponges, jellyfish, worms, flies, and humans, they were able to reconstruct the evolutionary history of all animals and determine which ones diverged from the common ancestor first.
Image credit: Alexander Semenov
The common ancestor of all animals was probably a soft-bodied creature that lived in the ocean about 600 or 700 million years ago. It did not leave any fossils behind, but by studying its living descendants, we can learn more about what it was like and how it gave rise to the amazing diversity of life we see today.
The study also revealed that ctenophores are very different from other animals in terms of their genes and their biology. For example, they have a unique way of developing from an egg to an adult, and they have a nervous system that is unlike any other animal’s. They also have genes that are not found in any other animal group, suggesting that they have evolved some novel features independently.
Comb jellies have many different species and they are all amazing, as testified by this video by MBARI.
The discovery of ctenophores as the oldest living creatures on Earth has important implications for our understanding of animal evolution and biodiversity. It shows that animals have been evolving for much longer than we thought, and that there are still many mysteries and surprises waiting for us in the natural world.
