News Round-Up

To push or to pull? How many-limbed marine organisms swim


When you think of swimming, you probably imagine pushing through the water—creating backwards thrust that pushes you forward. New research at the Marine Biological Laboratory (MBL) suggests instead that many marine animals actually pull themselves through the water, a phenomenon dubbed “suction thrust.”

The study, published in Scientific Reports, found that small marine animals with multiple propulsers—including larval crabs, polychaete worms, 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.

When the front appendage moves, it creates a pocket of low pressure behind it that may reduce the energy required by the next limb to move. “It is similar to how cyclists use draft to reduce wind drag and to help pull the group along,” says lead author Sean Colin of Roger Williams University, a Whitman Center Scientist at the MBL. MORE

Header image: Marine Biological Laboratory, University of Chicago.