Ghost Shrimp

Ghost shrimp are small, soft, and translucent crustaceans of the intertidal zone. Despite what their name and appearance suggest though, they are more closely related to crabs. Their carapace is usually very pliable, and their bodies are long and narrow, almost more lobster-like than shrimp-like. They typically reach up to 3 or 4 inches in length. Some of the species found on the Texas coast include the estuarine ghost shrimp (Lepidophthalmus louisianensis), the broadspine ghost shrimp (Dawsonius latispinus), and a somewhat more recently described species, Lepidophthalmus statoni. They range from a mostly-transparent pink to orangish, with white legs and tail fans, and one enlarged, wide claw.

To move around, ghost shrimp rely on drag-powered swimming. Drag swimmers move their limbs in a cyclic motion. When they push water backwards, this moves their body forward. But as their limbs return to the starting position, they push water forward, moving them backwards in the opposite direction their body is heading. This opposing force is called drag. It’s like a 3-steps-forward, 1-step-back mode of travel. Their not-entirely-efficient movement strategy is fueled by a diet of diatoms and dinoflagellates.

Estuarine ghost females reach maturity within their first year, at a length of less than half an inch – males, a little larger. Eggs become apparent beginning in December. The first juveniles large enough to be caught in samples appear by early spring. Some anglers use ghost shrimp as bait, sucking them out of their burrows with a plunger-like sand pump (limit of 20 per day). As they are also a food supply for migratory birds, some areas are protected from ghost shrimp harvest.

Commonly inhabiting the mud, sand, and clay of euryhaline inlets, estuaries, and protected shorelines, and generally found at the water's edge, ghost shrimp burrow down in seafloor sediments to collect bits of food. They can survive for up to six days without oxygen. The little volcano-like holes in the sand you can see at low tide are ghost shrimp burrows. These burrows, found in intertidal and shallow subtidal waters, can be up to 4 feet deep and are an important part of the intertidal ecosystem. They influence sediment structure and disperse oxygen and nutrients throughout the sediment. The oxygen helps organic matter decompose, enriching the sediment, which benefits the neighbors too.

An ecosystem is an interconnected system of organisms living in a landscape (or seascape). Removing an element can cause the system to change in unexpected ways, much like pulling out a Jenga stick. Some ecosystems are created by “ecosystem engineers.” Beavers, for example. Their dams alter the environment by flooding lowlands around rivers, and providing new habitat for fish, insects, plants, and birds. Burrowing shrimp, such as our ghosties, are also ecosystem engineers. But because they live out of sight underground, many people aren’t familiar with their architecture. At the water’s edge, the world underneath your toes is a complex and dynamic network of burrows and galleries – like the inside of an ant mound. These burrows are constantly changing and influencing their surrounding environment, mixing up and exchanging organic materials between the water and the sediment. Because they play a large role in balancing nutrient levels, if they suddenly disappeared, we don’t really know what the consequences would be, but a huge algal bloom seems likely.

Oysters are also ecosystem engineers, but because we like to eat them, they have a multimillion-dollar industry looking out for their interests. Unfortunately, ghost shrimp and oysters have some overlap in the habitat they prefer, so ghost shrimp often end up being labeled as pests. In some states, burrowing shrimp are even targeted with topical pesticides to clear more areas for oysters. However, some research has been carried out that will help identify likely areas of high and low shrimp growth, so that aquaculturists can choose locations that are productive for oysters but not disruptive to ghosties, allowing both to thrive in their respective environments.

Where I learned about ghost shrimp, and you can too!

Padre Island National Seashore
www.nps.gov/pais/learn/nature/ghostshrimp.htm

TPWD
tpwd.texas.gov/regulations/outdoor-annual/fishing/shellfish-regulations/crab-and-ghost-shrimp-legal-devices-and-restrictions

Texas Marine Species
txmarspecies.tamug.edu/invertdetails.cfm?scinameID=Lepidophthalmus%20louisianensis
txmarspecies.tamug.edu/invertdetails.cfm?scinameID=Dawsonius%20latispina
txmarspecies.tamug.edu/invertfamilydetails.cfm?famnameID=Ctenochelidae

World Register of Marine Species
www.marinespecies.org/aphia.php?p=taxdetails&id=101839#
www.marinespecies.org/aphia.php?p=taxdetails&id=421828#
www.marinespecies.org/aphia.php?p=taxdetails&id=954520#

National Library of Medicine
pubmed.ncbi.nlm.nih.gov/26250042/

Encyclopedia of Life
eol.org/pages/46517481
eol.org/terms/glossary/d/https:%2F%2Feol.org%2Fschema%2Fterms%2Fdrag_based_swimming

NOAA
www.fisheries.noaa.gov/feature-story/estuarine-engineers

Springer Link
link.springer.com/article/10.1007/s12237-016-0193-y

Oxford Academic
academic.oup.com/jcb/article-abstract/9/4/540/2327504?login=false