By nature, people like to know for sure the world around them, because only with certain knowledge can you make a reassuring decision. However, due to the nature of her work, science usually raises a series of uncertainties and new questions rather than an immediate 100% answer, slowly approaching more and more confirmed knowledge. This also happened when searching for the oldest animal. Jellyfish and sea sponges have been in the crossfire of this debate for about a hundred years, with one and the other winning, depending on the aspects examined.
The polygonal jellyfish is a free-swimming predator, while the sea sponge spends its life in one place and subsists on organic debris filtered from the water. These groups of animals are the simplest animals of our time, which is why they have become an object of research. For nearly a hundred years, sponges (due to their extreme simplicity: they have neither muscles nor nervous systems) have had the upper hand in this “competition”. About 15 years ago, with the advent of new genetic testing technologies, this age-old debate was revived, but so far no satisfactory answer has been found.
Undefined luminous sea sponge.
Source: MBARI
the nature Large-scale genetic mapping is behind research findings recently published in the journal. the University of California (Berkeley and Santa Cruz) and the University of Vienna MBARI Experts (Monterey Bay Aquarium Research Institute) analyzed groups of genes that are always located on the same chromosome, regardless of the animal (or human) being examined.
“Using a new method, we looked far back, at the possible origin of animal life. With the help of genetics, we took a journey through time of a billion years in order to obtain the most reliable evidence yet for the fundamental question of the first steps of evolution,” explained Darren Schultz, lead researcher. Animal “. “The finding provides a basis for the scientific community to more accurately understand the evolution of animals – and humans.”
Hyalonema bianchoratumSea sponge in the shape of a tulip.
Source: MBARI
Until now, genetic research has examined only individual genes, but now the relationship between groups of genes located on chromosomes. While the position of individual genetic sequences on a chromosome can change over time, the relationships between them rarely change, and when they do, it is an irreversible change. Researchers have examined relationships that have existed since ancient times. They succeeded in identifying patterns found in countless animals, the relationship of which can be traced back to the earliest point in animal evolution. Using this method, they demonstrated that jellyfish evolution diverged earlier than that of all other animals, and thus appeared before the common ancestor of other animals.
Polygonal jellyfish are very simple creatures, although they can appear more complex when swimming in the depths.
Source: Unnatural World
How do we imagine this event that occurred 700 million years ago? The ancestor of all animals, a single-celled creature, walked the road with offspring. One of the offspring, from which today’s polygonal jellyfish is formed, took a separate path, and during its subsequent development, the order of its genes on its chromosome was preserved, not much changed. He became the first separate representative of today’s fauna, that is, the brother of all subsequent animals. (For the avoidance of doubt: jellyfish are not our ancestors, but our eldest sister!) The other offspring, from which sponges and all other animals that exist today, took a different path. In the course of evolution, the order of genes on your chromosome got mixed up, a fusion of chromosomes occurred – these shifts are irreversible, you can still find them to this day, so with their help you can advance back to the original path. By tracing the metamorphoses, the researchers discovered that jellyfish is the most ancient animal.
The evolution of animals based on the data just discovered, illustration. On the left side is the polygonal jellyfish as the first animal to separate, and on the right side are all the other animals that separated only later.
Source: MBARI
Animals and unicellular (but not zoonotic) relatives were used in the studies, such as during genetic comparisons between collared jellyfish, similar patterns were found between fin jellyfish and unicellular patterns, but different in the case of other animals. This means that jellyfish diverged from this evolutionary sequence before the changes found in other animals.
With this discovery, the chance that sponges were the first animals to diverge is merely mathematical chance, since, while not impossible, it would have required a series of unusual coincidences.
