In this first video you can see our subject looking kind of cute and shy (awwww!). Pay attention to the dorsal (top) vessel and you’ll see the “human-like blood” being pumped through the worm’s closed circulatory system (just like us!). In Nereis, the dorsal vessel itself does most of the pumping. Also note double eye spots (this guy is literally a four-eyes) and the leg-like parapodia with their bristly setae.

But in this video you’ll find Nereis has a second, distinctly not cute side: vicious predator. Watch for it to evert its pharynx, and particularly watch for the TWO GIANT FANGS (technical term: jaws) on the end. You can also see the pumping blood at the beginning of this film. Unfortunately, this one is a bit dark.

Although you may be tempted to think these guys are closely related to millipedes and centipedes, they’re not. This is yet another case of  — you guessed it — convergent evolution.