Back around when worms wriggled out of saltwater and into ... leaving earthworms, leeches, and their other clitellate relatives with the most scrambled genomes known. "Everything broke and then ...

or bristle worm (polychaete is Latin for "many bristles"). Related to earthworms and leeches, there are over 8,000 named polychaete species. They have segmented bodies, with loads of little ...

Photomacrograph of the medicinal leech Hirudo verbana. Leeches are aquatic, blood sucking, segmented worms, which mainly feed on mammalian blood. In a single feed they can consume over 3 times their ...

Getty Images/iStockphoto “Leeches are blood-sucking endoparasite segmented worms characterized by a small sucker, which contains the mouth, at the anterior end of the body, and a large sucker ...