Strange creatures do not have both anus and anus, but survive for over 500 million years

What mechanism helps this worm survive? That's what surprised scientists.

Under the sand in temperate seas there exists a strange creature. Their scientific name is Paracetenula , which belongs to the flatworm family so it has a long and slender body.

What makes this creature get the attention is that it has no mouth, no anus, not even a "heart" (gut) for good. More strangely, with such a pre-existing body, it still lives extremely well, when present on this Earth from more than 500 million years ago.

How this worm survives is the question that experts have to suffer. However, science has recently had an answer after an intensive study of this organism.

The answer lies in Riegeria - the bacterium that lives symbiotic with this worm. They are the key to eating Paracetenula for hundreds of millions of years without needing a mouth or intestines.

According to Harald Gruber-Vodicka, a microbiologist at the Max Planck Institute in Germany, for millions of years, Riegeria has "encapsulated" their genomes, holding only essential functions. They live in parts called "trophosomes" that account for most of the worm's body area.

Keep a close eye: this worm is just a piece of transparent color, and the white part is the body.

Riegeria is a " fusion" type , meaning they need chemical reactions to synthesize energy. Specifically, in this case, they use the reaction between CO ₂ and H ₂ S to produce organic compounds, and also help the worm absorb nutrients from within.

Although "eat in beans" , this bacterium does business well. The nutrients they produce have both fat, protein, sugar, fatty acids and vitamins.

"We have not seen such a symbiotic relationship. That is, even if the genome is dissipated, only a single species of bacteria can produce a great amount of nutrition for the host." - Gruber-Vodicka said.

In fact, the symbiotic relationship between bacteria and host in nature is related to chemistry is nothing new. However, the way this bacterium works makes scientists feel admired, because in most common symbiotic relationships, hosts often digest bacteria to absorb nutrients. of them.

As for Paracatenula and Riegeria, the bacteria create nutrition right in the host's body. And according to an analysis from an electron microscope, this bacterium has created microscopic droplets of nutrients that the worm can absorb.

"It's like a fruit garden. Bacteria constantly result in eating worms. In other symbiotic relationships, bacteria are often removed completely after completing tasks."

Gruber-Vodicka says this is like a perfect system. All individuals have what they need, leaving nothing behind.

"The worm does not have a secretory component, but it does not need to be excreted. It seems that all the nutrients the bacteria produce are fully utilized."

The study is published in the PNAS scientific journal.