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Mixed Up Myxozoans

November 24, 2015

Microscopic fish parasites called myxozoans are actually animals with stripped down jellyfish genes.


Right photo PCartwright

Left, myxozoan spores from Kudoa iwatai. Each spore is approximately 10 micrometers in width (Photo: A. Diamant). Right, the jellyfish Aurelia aurita (moon jelly). The bell is approximately 25 centimeters wide or 2,500 times larger than a myxozoan spore. (Photo: P. Cartwright)


Are myxozoans mixed-up? I’m Bob Hirshon and this is Science Update.

Microscopic parasites called myxozoans use stingers to grab onto salmon and trout. They burrow in, causing neurological damage that makes the fish swim in circles. Now, a genetic study in the Proceedings of the National Academy of Sciences has confirmed that myxozoans are actually tiny animals descended from jellyfish, that share a similar stinger. 

PAULYN CARTWRIGHT (University of Kansas):

We found that myxozoans have a tiny genome; 20 to 40 times smaller than their free-living jellyfish relatives.


That’s University of Kansas evolutionary biologist Paulyn Cartwright. She says myxozoans are made up of just a few cells, and have lost many genes important for multicellular development in animals.

CARTWRIGHT (University of Kansas):

We tend to think of animals evolving from much more microscopic organisms into complex multicellular  organisms, but it can go the reverse. 


I’m Bob Hirshon, for AAAS, the science society.