How Squid Swim: The Difference Between Theory and Observation


For years, some engineers believed squid likely propelled themselves through water by creating vortex rings, forcing fluid out of their pipe-shaped funnels to create smoke-ring-like structures. But the experience of WHOI researchers suggested otherwise, so they set up experiments to check the theories against observational evidence.  They put live squid into a flume at WHOI’s Rinehart Coastal Research Laboratory, added microscopic, silver-coated beads to the water, shined laser light on the squid and beads, and imaged the motion of their experimental ocean. This technique allowed them to visualize and measure the jet emitted from the squid and the water streaming by. By analyzing the flow, scientists found that squid propel themselves with prolonged column-shaped jets, like the flow from a garden hose. The study, one of several underway on biomechanics, could help in the design of various ocean instruments as well as aid scientists in understanding how animals move in the ocean.