Barrel jellyfish may hunt with new kind of math

Studying the dive patterns of the jellyfish Rhizostoma octopus shows they use a new kind of Lévy walk, a type of mathematical pattern, to find food.

© Prof. Graeme Hays

Barrel jellyfish are big. Weighing almost 30 kilograms, the creatures need a lot of food to fuel their massive size. As a result, the gelatinous blobs spend a lot of time floating up and down in their home waters, with movements that change over time.

Because the jellies’ movements didn’t seem to be consistent, scientists didn’t think Rhizostoma octopus sought food using Lévy walks, a series of small steps mixed with long hops that have been shown to be an efficient foraging strategy for honey bees, sharks and even humans.

A closer look at barrel jellies’ diving patterns, however, suggests that they use a new kind of Lévy walk with the help of water currents. The results, which appear August 6 in the Journal of the Royal Society Interface, also imply that the family of Lévy walkers could extend to include pollens, seeds, mites, spiders and insect larvae surfing air currents on a warm day.

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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