New research begins to unravel the secrets of a strange natural phenomenon in which thousands of freshwater crustaceans march on land
A group of shrimp that have left the safety of the water to parade upstream in Thailand.
When the shrimp leave the water they are easy prey for spiders, snakes, lizards and frogs that lay in wait along the riverbank.
Some individual shrimp travelled nearly 65 feet up-river and spent more than 10 minutes out of the water, according to the Times. “I was so surprised,” Hongjamrassilp tells the Times. “I never thought that a shrimp can walk that long.”
To investigate what drove the tiny shrimp out of the water, the researchers brought the crustaceans into the lab. After two years of tweaking the experiment, the team was finally able to get the shrimp to leave the water, according to National Geographic. It turned out, increasing the speed of the current and using water straight from the river were key to inducing this unique behavior in a lab setting. The researchers also found that darkness and cooler temperatures were also important cues for the shrimp to head for higher ground.
A large group of shrimp marching on land to make their way upstream alongside the Lam Duan Rapids of Nam Yuen city, Thailand. The crustaceans’ journey is mostly relegated to the riverbank’s splash zone, which researchers hypothesize may help keep the shrimps’ gills wet during their journey.
What remains mysterious is why exactly the shrimp are willing to risk it all to get upstream. Peter Novak, a freshwater ecologist at Western Australia’s Department of Biodiversity, Conservation and Attractions who was not involved in the study, tells National Geographic that the findings “raise interesting questions about why these animals are moving upstream if there is no need to be downstream in the first place.”
https://www.smithsonianmag.com/smart-news/thailands-great-shrimp-parade-180976452/