This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: At just an inch (2.5 centimeters) long, the sand hoppers skipping across California's Isla Vista Beach at dawn don't exactly look like a force of nature. But a new study reveals that these shrimp-like creatures might be doing more to shape the landscape in which they live than any other animal on Earth.
"The impact of animals on beaches is a really understudied area, especially considering how much work they're doing," said Tim Baxter, a physical geographer at the University of Oxford's Pitt Rivers Museum and the study's lead author. "Sand hoppers are often overlooked or considered a bit of a nuisance. We wanted to try to look at them in a different light." The study appears in Journal of Geophysical Research: Earth Surface.
Sand hoppers are nocturnal crustaceans that live on sandy beaches all over the world, feeding on washed-up seaweed and kelp. Each industrious little hopper digs a new home every night, kicking up mounds of fluffed-up sand onto the beach by dawn. Burrowing helps them find food, stay moist and hide from predators.
To measure hoppers' influence on the landscape, researchers staked out study plots on the beach at night after high tide, then scraped off all the sand the hoppers had piled up by morning. The team bagged and weighed the excavated sand, then dug up chunks of beach sand to count hoppers in each study plot. Based on the amount of sand and the total mass of hoppers, each hopper digs up more than 10 times its own body weight for every burrow.
For every three feet (one meter) of coastline, around 21,450 sand hoppers collectively move around 110 pounds (50 kilograms) of sand—about 16 half-gallon sandcastle buckets' worth—every night. By combining these numbers with eight years of previous measurements of hopper populations along the beach, the team was able to extrapolate the crustaceans' full influence across 15.5 miles (25 kilometers) of beaches near Isla Vista, California. All told, the sand hoppers in that stretch have as much sediment-shifting power as some nearby rivers, moving around 310 tons of dry sand per day.
"I have to admit, I did go back through the numbers multiple times just to double-check my calculations. I was extremely surprised by how much they dug up," Baxter said. "It's a really good example of how individually small animals occurring in high numbers can have really substantial landscape-shaping impacts," said Gemma Harvey, a physical geographer at Queen Mary University of London who was not involved with the study.
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