https://www.science.org/content/article/earthworms-have-completely-scrambled-genomes-did-help-their-ancestors-leave-sea?
Science
Earthworms and their marine cousins, bloodworms, can look a lot alike. So much so that if you grab a container of bait worms from a tackle shop, you’d be forgiven for not knowing whether they came from soil or muddy seabed. But you’d scarcely think they were relatives from the arrangement of their genes, new research suggests. That’s because the group of worms that wiggled out of the ocean hundreds of millions of years ago—members of the class Clitellata—have completely reorganized their genes, landing many in new spots along their chromosomes. In terms of genome structure, a bloodworm looks more like a clam than its dirt-dwelling relatives.
“Clitellates have the most scrambled genomes among animals studied so far,” says Yi-Jyun Luo, an evolutionary biologist at the Biodiversity Research Center, Academia Sinica and leader of one of three groups that independently came to this conclusion this year when studying annelids, the phylum that includes all segmented worms.