If you remember your biology lessons at school you’ll know that every animal on earth feeds, reproduces and breathes – but now that basic rule has been broken.
A tiny "alien" parasite called Henneguya salminicol, which infects the muscles of fish and other undersea creatures, is descended from jellyfish but over time has lost anything it didn’t need to survive.
And one of the things that H. salminicola has thrown away over the years is its mitochondrial genome – the component of DNA that (among other things) rules respiration.
Dorothée Huchon, an evolutionary biologist at Tel Aviv University in Israel, told Live Science: ”They have lost their tissue, their nerve cells, their muscles, everything."
World's largest bacteria-eating virus 'blurs line between life and death'
Fish that survive out of water for years could stop ageing in humans
"And now,” she added, “we find they have lost their ability to breathe."
While the tiny creature does contain a structure that’s similar to mitochondria, it doesn’t have the ability to metabolise oxygen.
“These are not true mitochondria,” says Huchon.
Over countless millennia, H. salminicola has streamlined itself from a simple jellyfish in the myxozoa family to a strange alien-like creator that obeys hardly any of the rules that govern life on earth.
Today's Top Stories
With no ability to breathe it’s not clear how H. salminicola survives. It may be that it’s sucking energy directly from other sea creatures.
"Animals are always thought to be multicellular organisms with lots of genes that evolve to be more and more complex," Professor Huchon said.
"Here, we see an organism that goes completely the opposite way. They have evolved to be almost unicellular,” she added.
Although H. salminicola is harmless to humans, it is a major problem for fish farmers because it creates nasty-looking white spots in the flesh of infected fish.
Source: Read Full Article