Researchers have not been able to wrap their heads around how life has come to be on our planet. Ancient beliefs about what life needs to be able to develop have been questioned and, sometimes, proved entirely false. Scientists have now uncovered that an incredibly unique animal exists that doesn’t even require oxygen to survive, which was so far thought to be necessary for all living beings.
This animal is named Henneguya salminicola, and it is a small parasite that spends its life inside of fish, most commonly in salmon. Scientists have discovered that this species does not need oxygen to live, but haven’t yet been able to understand how that works.
Researchers that are looking into the species have realized one very peculiar thing, which makes them unique. They lack a mitochondrial genome and the hard-coded genes which enable cellular respiration. Mitochondria are called the “powerhouses” of cells for animals. The process of respiration involves using oxygen and glucose and releasing carbon dioxide. This study was made available in Proceedings of the National Academy of Sciences.
According to the scientists, H. salminicola has not just gotten rid of its mitochondrial genome, but it has also lost almost all of its nuclear genes, which transcribe and replicate the mitochondrial genome. On the other hand, many genes within H. salminicola have been found that encode proteins in different pathways within the mitochondria and reached the conclusion that genes involved in aerobic respiration or the replication of mitochondria’s DNA was either missing or only present as so-called pseudo-genes.
In layman’s terms, the small cells do not have the genetic method to receive oxygen, but they are very obviously alive. The fact that they are parasites is an important clue, as parasites do not use the mitochondria the same way as other animals do. This doesn’t explain, however, what H. salminicola uses instead of oxygen or how they survive.