Article Source: Scientific American / 2015
Once upon a time, a jellyfish became a parasite, and its descendants became unrecognizable.
Several are worms. Most are microscopic shapeless sacs. They produce spores, a behavior almost of unheard of among animals, and pass the majority of their lives freeloading inside animals.
Taken together, they look and act an awful lot like protists – microbes that swarm in ponds, in soil, and sometimes in bloodstreams (think malaria). They were mistaken for such for over 100 years. But I’d wager 99% of protists do not have ancestors that were large, free-living animals. These do.
And they are legion: some 2,000 species exist today. Now, thanks to a new study, we can state with more confidence than ever that they are all related to one another, and, in spite of their radically altered appearance, are indeed cnidarians -- the giant and ancient group of organisms that includes coral, jellyfish, sea pens, hydras, and sea anemones.
But you would never know it to look at them. Called myxozoans, they are wonderfully weird.
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