A team of researchers at the University of Kansas has spotted a surprising evolutionary progression, which might end up changing the way experts think about animal growth and development.

Genome sequencing of the microscopic aquatic parasites called Myxozoa (this parasite infect both invertebrate and vertebrate hosts) revealed that they are Cnidarians that have experienced extreme degeneration. During the study, the scientists found that features of the parasite are significantly similar to those of corals and jellyfish.

In a paper published recently in the Proceedings of the National Academy of Sciences, the research team wrote that Myxozoans cannot be described as a primeval form of jellyfish. According to the team, these creatures are smaller fish that decreased in size and became more simplified as time passed by.

In spite of progressive degeneration of the genome and body structure of modern jellyfish, Myxozoa managed to retain the most vital characteristic of jellyfish, its nematocyst or stinger. The study’s lead researcher Paulyn Cartwright further informed that Myxozoa is made of just a few cells and doesn’t possess a mouth or a gut.

Cartwright added that the genomes of this parasite were found to be 20-40 times tinier compared to those or average jellyfish. This finding automatically makes the genome of Myxozoa one of the tiniest animal genomes to have ever been reported. Myxozoa boasts around 20 million base pairs while an average Cnidarian is known to possess over 300 million base pairs.

Cartwright said that due to the weird combination of features observed in Myxozoans, it’s quite difficult to think that they are jellyfish. Animals are typically categorized as macroscopic multicellular organisms and the Myxozoans evidently don’t possess those traits. So, Cartwright and her colleagues had to conclude that Myxozoa completely redefines our idea of animals.

Myxozoans are found both in marine habitats and freshwater and include an assorted clan of over 2,000 different microscopic parasites. Earlier, scientists used to classify those parasites as Protists, but biologists have questioned that classification.

According to the biologists, Myxozoans come with a polar capsule, which is a pretty elaborate structure that provides these creatures with the ability to latch onto their hosts. The last capsule of a Myxozoa has significant resemblance with a jellyfish’s stinger.