It's International Polychaete Day! Did you know that small marine animals with multiple propulsers — including polychaete worms, larval crabs, and some types of jellyfish— don’t push themselves forward when they move their appendages, but instead create negative pressure behind them that pulls them through the water? The phenomena is known as "suction thrust." Learn more: go.mbl.edu/suctionthrust 📸 : Polychaete worm (Tomopteris) with setae moving on each side of the body in metachronal waves. C