Myxozoans are microscopic parasites that make for mayhem on commercial Pisces the Fishes stocks by stimulate neurological problems : Salmon and trout grow what ’s called whirling disease and start swim in circle . research worker studying the genomes of these plebeian sea pests reveal that myxozoans are actually parasitic “ micro jellyfish , ” ended with stinging tentacles . They ’re extremely contract , plunder - down cnidarians , the phylum that includes jellyfish , coral , and sea anemones , according to findings published inProceedings of the National Academy of Sciencesthis week .
There are over 2,180 species of myxozoans , allobligateendoparasites and typically just a few cubicle measuring 10 to 20 microns in width . Back in the eighties , they were thought to be single - celled organisms ( like protist ) , and not animal . It was n’t until their DNA was sequenced did researcher realize that they were in fact fauna , just drastically simplified ace . " Animals are usually define as macroscopical multicellular organisms , and this is not that,“Paulyn Cartwrightfrom the University of Kansas says in astatement . " Myxozoa utterly redefines what we recollect of as beast . "
Intriguingly , their jail cell hold in a complex little complex body part that helps ease attachment to the host . It ’s called a polar capsule , and it bears a scratch resemblance to nematocysts , the stick cells of jellyfish tentacle . To well understand the dramatic evolutionary transition from a gratuitous - support cnidarian to a microscopical endoparasite , Cartwright and co-worker analyze sequences from two distantly related myxozoan specie , Kudoa iwataiandMyxobolus cerebralis . Then they compare these to the genome of a less subjugate cnidarian sponger calledPolypodium hydriforme .
The team confirm that myxozoans are , in fact , cnidarians and a sister group toPolypodium . " This is a remarkable case of uttermost degeneration of an animal soundbox plan,“Cartwright adds . And not only have these micro jellyfish develop a stripped - down physical structure design of just a few cells , but myxozoans also have one of the smallest animal genomes ever describe : about 20 million stem brace only . The average cnidarian has over 300 million .
Despite the extreme paring down , myxozoans have retained a key jellyfish characteristic – nematocysts and the genes needed to make them . Still , they lack many of the traits we used to remember are life-sustaining for animal evolution . They ’re a spectacular example of how obligate parasitism can lead to a monumental decrease of body plan , genome sizing , and gene cognitive content .
