Released by Brendan M. Lynch, KU News Service
It’s a shocking discovery that may redefine how scientists interpret what it means to be an animal. This week in the Proceedings of the National Academy of Sciences, researchers at the University of Kansas will reveal how a jellyfish — those commonplace sea pests with stinging tentacles — have evolved over time into “really weird” microscopic organisms, made of only a few cells, that live inside other animals.
Genome sequencing confirms that myxozoans, a diverse group of microscopic parasites that infect invertebrate and vertebrate hosts, are actually “highly reduced” cnidarians — the phylum that includes jellyfish, corals and sea anemones.
“This is a remarkable case of extreme degeneration of an animal body plan,” said Paulyn Cartwright, associate professor of ecology and evolutionary biology at KU and principal investigator on the research project. “First, we confirmed they’re cnidarians. Now we need to investigate how they got to be that way.”
Not only has the parasitic micro jellyfish evolved a stripped-down body plan of just a few cells, but via data generated at the KU Medical Center’s Genome Sequencing Facility researchers also found the myxozoan genome was drastically simplified.
“These were 20 to 40 times smaller than average jellyfish genomes,” Cartwright said. “It’s one of the smallest animal genomes ever reported. It only has about 20 million base pairs, whereas the average Cnidarian has over 300 million. These are tiny little genomes by comparison.”
Despite its radical phasedown of the modern jellyfish’s body structure and genome over millions of years, Myxozoa has retained the essential characteristic of the jellyfish — its stinger, or “nematocyst” — along with the genes needed to make it.
While the dramatic changeover from macroscopic marine animal to microscopic parasite seems utterly unique, Cartwright thinks it might reveal a strategy in nature that could be more widespread than previously known. “If it can happen once in evolution, it certainly can happen again,” she said.
More about the University of Kansas’ research is online at www.ku.edu/research.
For more information on the Proceedings of the National Academy of Sciences, visit their website at www.pnas.org.