From Science Magazine.

Tiny aquatic organisms like plankton are considered passive drifters, moving at the mercy of ocean currents. But reporting in the Journal of Experimental Biology, scientists show some of these microorganisms don’t just drift—they surf.

The researchers chose a zooplankton—the larvae of the common slipper shell snail. They placed 2000 of the larvae in a small tank equipped with eight water jets, which created different levels of turbulence similar to ocean currents. The scientists then added tracer particles to the water tank and shined a plane of laser light through the tank’s center, which allowed them to trace the planktons’ changing velocity and direction.

The turbulence traps a larva in a vortex, which has fluid moving up one side and down the other. The larvae are negatively buoyant, or tend to sink, so they swim upward to stay adrift. A vortex in a turbulent flow, represented by the light-blue vectors (water velocity relative to the larvae), tilts the plankton into downward-moving fluid, making them sink further. However, the larvae also tilt their bodies against the swirl and swim to the other side, into upward-moving fluid, represented by the dark blue vector (plankton velocity relative to the fluid). Because the larva repositions itself in a direction pointing toward upward fluid velocity, it takes advantage of the turbulent flow to travel aloft.

By surfing the flow, mature larvae double their average speeds, making them better hunters of other phytoplankton in the upper layers of the ocean.

Read more: https://scim.ag/4buWCbM

FOOTAGE CREDIT: MICHELLE DIBENEDETTO

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