The term “sand flea” is commonly used to describe small, hopping creatures found near coastal environments, often leading to confusion about what these organisms truly consume. These inhabitants of the beach ecosystem play an important role in processing organic materials that wash ashore. To understand their diet, it is necessary to distinguish between the different organisms that share this common, non-scientific name.
Clarifying the Organism
The name “sand flea” most often refers to two entirely different kinds of arthropods that are not closely related. The creature most people encounter on temperate beaches is an amphipod, a small crustacean belonging to the family Talitridae, commonly known as a beach hopper or sand hopper. These organisms are relatives of shrimp and crabs, living primarily in the sand above the high-tide line.
The second organism, found in tropical and subtropical regions, is the chigoe flea, Tunga penetrans, which is a true insect and a member of the flea order Siphonaptera. This type of sand flea lives in soil and sand but requires a warm-blooded host for its parasitic diet. This fundamental difference in classification dictates their vastly different feeding strategies.
The Scavenging Diet of Beach Hoppers
Beach hoppers are detritivores, meaning their diet consists entirely of non-living organic matter found along the shoreline. They primarily consume “wrack,” which is the collection of decaying seaweed, surfgrass, and other plant debris deposited by the tide. Specific food sources include stranded kelp and eelgrass, where they often congregate for both shelter and sustenance.
These crustaceans use their mouthparts to shred and ingest the rotting vegetation, acting as a crucial first step in decomposition. They also scavenge on microscopic algae, diatoms, and the remains of dead invertebrates or fish washed ashore. Some species consume a remarkable amount of food, eating up to half their own body weight in a single night.
Feeding Behavior and Ecological Function
Beach hoppers are typically nocturnal feeders, emerging from their burrows in the damp sand after sunset to forage along the high-tide line. This behavior helps them avoid desiccation from the heat and evade visual predators like shorebirds. They also burrow directly into piles of decaying seaweed during the day to find food and maintain humidity.
Their consumption of stranded organic debris prevents the accumulation of rotting material on the beach. By shredding and digesting the wrack, they accelerate the breakdown of this matter. This process recycles nutrients back into the coastal ecosystem, making beach hoppers a natural cleanup crew. Their bodies also become a food source for shorebirds and crabs, transferring energy higher up the food chain.
The Parasitic Diet of Chigoe Fleas (Tunga)
The chigoe flea, Tunga penetrans, relies on blood and tissue from a living host. Adult male chigoe fleas and newly emerged females feed intermittently on warm-blooded animals, similar to other types of fleas. However, the female’s diet becomes parasitic and sedentary once she is ready to lay eggs.
The mated female burrows headfirst into the skin of a host, which can include humans, livestock, and other mammals, usually on the feet. Once embedded, she feeds on the host’s blood and surrounding tissue. Her abdomen swells dramatically as she develops eggs, utilizing the host’s resources for reproduction. She remains embedded for about two weeks, feeding and shedding eggs, before she dies and is sloughed off.