UC Santa Barbara beach. Photo Credit: Dave Hubbard
A California beach may look still and quiet, but beneath the surface, thousands of tiny crustaceans are constantly moving sand.
A new study found that sand hoppers (Megalorchestia spp.) can excavate as much as 50 kilograms (110 pounds) of sand per meter of shoreline per day. Across a 25-kilometer (15.5-mile) stretch of Southern California coast, their collective activity adds up to an estimated 310 tons of sand moved every day.
Published in the Journal of Geophysical Research: Earth Surface, the study offers a new perspective on how animals contribute to the physical processes that continually reshape California’s coastline.
Sand hoppers are small, shrimp-like crustaceans found on sandy beaches around the world. They feed on kelp and other organic material washed ashore, spending daylight hours sheltered beneath seaweed or inside the sand. After dark, they emerge and dig new burrows, sometimes reaching 10 to 30 centimeters (4 to 12 inches) below the surface.
Their preferred habitat lies between the saturated sand near the water and the dry sand farther up the beach. Unlike some burrowing animals that reuse the same shelter, sand hoppers regularly create new burrows, continually disturbing and redistributing sediment.
To measure their impact, researchers conducted a field experiment at Isla Vista Beach, next to the UC Santa Barbara campus. Following a summer high tide, they marked plots in the sand hoppers’ preferred zone and left them overnight.
Burrowing talitrids create a well-defined bioturbation zone on gently sloping sandy beaches in southern California. (a) Location of study site. (b) The burrowing zone (black dashed line) on Isla Vista Beach on a typical summer’s day. (c) Photograph of Megalorchestia spp. provided by Nicholas Schooler. (d) Rectangular metal frames used to estimate the mounding rate of burrowing talitrids. (e) Diagram showing the spatial arrangement of the 21 sampling plots (not to scale).
By morning, the smooth sand had been transformed by the animals’ activity. Researchers collected and weighed the excavated sand and compared those measurements with the number of sand hoppers in the study areas.
The results were striking. Individual sand hoppers can excavate more than 10 times their own body weight in sand, while dense populations can collectively move enormous quantities of sediment. The team combined its field measurements with longer-term population observations to estimate the animals’ impact across the broader coastline.
Beaches are constantly reshaped by waves, tides, currents and wind, yet the role of animals in these processes has received far less attention. The researchers’ calculations suggest that sand hoppers along the study coastline move amounts of sediment comparable to the daily loads of some major Southern California rivers and to longshore transport, which carries sand along the shoreline.
The findings add to the growing field of biogeomorphology, which examines how living organisms interact with and alter physical landscapes.
Sand hoppers do more than move sediment. Their burrowing helps redistribute organic material and nutrients through the beach and increases the movement of oxygen within the 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.
Their digging also loosens sand, potentially making it easier for wind and water to transport individual grains. This could influence the development of coastal dunes, which can help buffer shorelines from waves, storms and flooding.
Sand hoppers are also part of the coastal food web, consuming kelp and other organic debris while serving as prey for shorebirds and fish. Other beach organisms, including sand crabs and bloodworms, also move sediment, although their contributions are more difficult to measure.
Video Footage: Kyle Emery
The research has a strong connection to the University of California, Santa Barbara (UCSB) and its Marine Science Institute.
Lead author Timothy Baxter, now a research fellow at the University of Oxford’s Pitt Rivers Museum, conducted his postdoctoral research at UCSB with geography professor Ian Walker. During that time, Baxter developed collaborations with marine scientists Dave Hubbard, Kyle Emery and Jennifer Dugan, helping lay the groundwork for the study.
Four of the UCSB researchers—Hubbard, Emery, Dugan and Walker—are principal investigators at the Marine Science Institute.
Together, the researchers highlight how animals can be active participants in shaping coastal landscapes, alongside the more familiar forces of waves, wind and tides.
Researchers and Affiliations
- Timothy Baxter — Pitt Rivers Museum, University of Oxford
- Dave Hubbard — Marine Science Institute, University of California, Santa Barbara
- Kyle Emery — Marine Science Institute, University of California, Santa Barbara
- Jennifer Dugan — Marine Science Institute, University of California, Santa Barbara
- Winter Adams — Marine Science Institute, University of California, Santa Barbara
- Sebastian Alvarez — Department of Geography, University of California, Santa Barbara
- Ian Walker — Marine Science Institute and Department of Geography, University of California, Santa Barbara
Source & Adaptation
Adapted from original reporting by Sonia Fernandez, “Tiny beach-dwelling crustaceans are big-time sand movers, shaping the California coast,” The Current, UC Santa Barbara, 2026.
The research was published in the Journal of Geophysical Research: Earth Surface in the study “Mega Mounders: Burrowing Talitrids (Megalorchestia spp.) Excavate Large Quantities of Sand on California Beaches,” by Timothy Baxter and colleagues.
Photo Credit: Dave Hubbard