Tiny beach-dwelling crustaceans are big-time sand movers, shaping the California coast
University of California - Santa Barbara
(Santa Barbara, Calif.) — Stand on the damp sand on a California beach and chances are you’re standing on top of an active earthworks site. Sand hoppers (Megalorchestia spp.), the tiny, shrimp-like creatures commonly found eating away at kelp on the shore, have been found to move massive amounts of sand, excavating up to 50 kg (110 lbs) of sand per meter of shoreline per day.
“They have one of the highest rates of bioturbation of anything on the planet,” said UC Santa Barbara marine scientist David Hubbard, referring to the process of displacement of sediment by living organisms.
The sheer volume of sediment moved by these crustaceans, according to Hubbard and fellow coastal researchers, puts these amphipods on par with coastal longshore processes and some major Southern California rivers. Their findings, published in the Journal of Geophysical Research: Earth Surface, puts new perspectives on the roles of these and other sand-dwelling creatures in the physical processes that shape the coast.
The sandy beach’s tiny engineers
Though they may look stationary, sandy beaches act like rivers of sediment, constantly moving sand transported by waves, winds and currents along the coast. The beach is but one part of a bigger system called a littoral cell that cycles sediment from its sources, such as cliffs and dunes that back some beaches, or rivers and streams that carry sediment from coastal watersheds, or onshore processes that push sand from nearshore to the beach. Beaches serve as reservoirs for sand as it continues its way along the coast.
While coastal sediment transport processes are well known, the impact of the animals that live in this highly dynamic environment is less understood. It became an intriguing question for Tim Baxter, a physical geographer interested in interactions between wildlife and their physical environment in the coastal zone. When he moved from the UK to UCSB a few years ago to complete his postdoctoral work with geography professor Ian Walker, Baxter found in marine scientists Dave Hubbard, Kyle Emery and Jenny Dugan a complementary curiosity about sand hoppers. These tiny crustaceans burrow 10-30 cm (4-12 inches) into the sand, or hide under washed-up seaweed, emerging after dark to feed on kelp wrack.
“We combined our interests and started thinking about the abundance of sand hoppers around UCSB, but also across California,” said Baxter, who is now a research fellow at the University of Oxford. “That got us asking, how much are they digging? What are they contributing to the sediment system and sediment transport on these beaches?”
To find out, they devised a simple field experiment at Isla Vista Beach, a bluff-backed stretch of shore adjacent to the UCSB campus. After high tide on a summer night, when the waves had smoothed the sand and the tide had begun to recede, they sectioned off an array of sampling plots with metal frames in the sand hoppers’ preferred burrowing zone.
“They don’t like saturated sand that’s like liquid — their burrows collapse immediately,” Hubbard explained. “They don’t like the powdery dry sand above the high tide line. They like the Goldilocks sweet spot in between where the burrow will stay intact because the moisture in the sand is just right.” According to the paper, unlike burrowing animals that create a single burrow and reuse it, sand hoppers create fresh burrows every day in search of the perfect sand moisture, excavating sand that has been recently reworked by wind or wave action.
After waiting overnight to let the sand hoppers do their thing, the team went back to their plots to check on the mounds of sand left by all the burrowing action.
“When we came back in the morning, we couldn’t even see some of the frames,” Hubbard recalled. “They were completely buried, and we were so glad we had put flags next to them just in case.” Despite all the years studying these creatures close up, he was still slightly shocked at how much sand they could move overnight, he added.
After collecting and weighing the excavated sand, the researchers calculated that the sand hoppers had moved up to 50 kg of it, making these centimeter-long crustaceans among the most active sediment movers in the animal world.
“It was quite impressive and we weren’t really expecting that,” Baxter said. “I think for me that was the biggest shock.”
The findings add another dimension to the role of sand hoppers in the California coastal environment. Not only are they a fundamental part of the food web, eating kelp wrack and in turn becoming food for shorebirds and fish, their burrowing habits also cycle nutrients into the deeper layers of sand.
“There’s a huge churn,” Hubbard explained. “If food like kelp or carrion gets deposited on the beach, it’s going to get buried by them, which makes it available to a different group of organisms.” Additionally, the burrows aerate the sand, providing oxygen for aerobic microbial processes, he said.
The excavations also make the sediments more available for erosional processes, Baxter added, loosening the sand to be borne away by wind or water. “It potentially increases the roughness of the surface of beaches, which has implications for the formation of landforms such as coastal sand dunes.” Coastal dunes have lately become an important nature-based strategy for dealing with coastal flooding and sea level rise, as the self-building, self-healing landforms are able to take the force of increased wave and storm action.
The sheer amount of sand displaced by the sand hoppers, the researchers found by extrapolating their results across 25 kilometers (15.5 miles) of Southern California coastline, is comparable to the daily sediment loads of some major Southern California rivers and to longshore drift processes that move sand along the intertidal beach, Baxter said. While the field of biogeomorphology — which studies interactions between living things and their landscapes — has been gaining momentum in the last few decades, the activity of animals and plants on the landscape has still been relatively understudied compared to natural processes, he added.
“I think part of that is the influence of animals on these processes is seen as quite temporary, quite localized and small,” Baxter said. “What we are trying to show in this study is that actually these activities and interactions are operating on a lot larger scale and that their impacts are really worth highlighting.”
Article Title
Mega Mounders: Burrowing Talitrids (Megalorchestia spp.) Excavate Large Quantities of Sand on California Beaches
Article Publication Date
16-Sep-2026
Beach-burrowing beasties shovel more sand than any other animal on Earth
Millions of crustaceans shape California’s beaches: Here’s why their hard work matters
WASHINGTON — At only an inch 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 as a bit of a nuisance. We wanted to try and look at them in a different light.”
The study will appear Wednesday, 16 September in Journal of Geophysical Research: Earth Surface, AGU’s journal for the physical, chemical and biological processes that affect the form and function of the surface of the Earth.
Strength in Numbers
Sand hoppers are nocturnal crustaceans living in 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 up and weighed the excavated sand, then dug up chunks of beach sand to make hopper headcounts in each study plot.
Based on the amount of sand and the total mass of hoppers, each hopper digs up more than ten 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 up and down 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.
The Sand-Shoveling Olympics
Although Charles Darwin was already espousing the soil-shaping powers of English earthworms more than 150 years ago, scientists are still establishing the best ways to measure and compare the work of animals in their environments. “It’s a minefield with the different ways things are reported and measured in this field,” Harvey said.
Currently, though, of all digging and burrowing animals studied, California’s sand hoppers only have one potential rival. A previous study documented a South African sand prawn that mixes as much as 9 pounds of sand per square foot of beach per day (12 kilograms per square meter per day).
But Dave Hubbard, an ecologist at the University of California Santa Barbara and co-author on the study, is firmly team hopper: “If we had measured the sand hoppers’ total churn rate, it would have been more than the sand they were putting in mounds on the surface. They would probably win against the sand prawns.”
Stewards of the Environment
The sand hoppers’ hard work has knock-on effects on the entire beach. Their burrowing brings plankton and oxygen-rich seawater into the sand providing nutrients for other beach-dwellers. Their excavated mounds create loose grains of sand that might be blown around by the wind, potentially helping build dune habitats higher up the beach. The hoppers themselves are even a favorite food for shorebirds.
Sand hoppers also aren’t the only critters at work. Just a few feet closer to the water, blood worms and sand crabs mix and move sand, but without leaving behind easy-to-measure mounds for researchers to collect. Not only could these creatures be moving underappreciated quantities of dirt, their efforts could also be interacting with the sand hoppers’ burrowing — something that Hubbard is keen to study next. Accounting for the combined effects of all the animals together would enable scientists to fully see the importance of animals compared to physical processes like the action of wind and waves. “The beach ecosystem involves both the organisms that live in it and the landscape that forms it — they’re components of the same thing,” Baxter said.
These interwoven systems are easily disrupted by practices like beach grooming, where tractors rake the sand to smooth out the beach and remove seaweed for human visitors, tearing up hoppers and their burrows.
“They disturb the whole thing. You end up with kind of a desert,” said Hubbard, who visits Santa Barbara’s beaches almost every morning. As scientists learn more about the creatures that shape our favorite coastal places, Hubbard and Baxter hope to see beach management approaches take these overlooked engineers into account.
“Animals aren’t passive inhabitants of our landscapes, they're actively shaping them and can help restore them,” Harvey said. “The first step is knowing they're there and having these significant impacts so we can adapt accordingly.”
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Notes for journalists:
This study will be published in Journal of Geophysical Research: Earth Surface, an AGU journal. This press release and study are under embargo until 16 September 2026 13:00 UTC (9:00am EDT). Journalists may request an embargoed copy of the study by emailing news@agu.org. The study will be available to view and download at this link after the embargo lifts: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2026JF009312
Additional images and video of sand hoppers, the experimental setup, and the beach location are available upon request.
Paper title:
“Mega Mounders: Burrowing Talitrids (Megalorchestia spp.) Excavate Large Quantities of Sand on California Beaches.”
Authors:
- Timothy Baxter, Pitt Rivers Museum, University of Oxford, Oxford, UK.
- Dave Hubbard, Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA.
- Kyle Emery, Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA.
- Jennifer Dugan, Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA.
- Winter Adams, Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA.
- Sebastian Alvarez, Department of Geography, University of California Santa Barbara, Santa Barbara, California, USA.
- Ian Walker, Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA; Department of Geography, University of California Santa Barbara, Santa Barbara, California, USA.
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Article Title
Mega Mounders: Burrowing Talitrids (Megalorchestia spp.) Excavate Large Quantities of Sand on California Beaches
Article Publication Date
16-Sep-2026
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