The Sand Fleas Myth

Updated: Sep 11, 2020

When you visit the beach, do you ever notice that the sand is...jumping? "No, that makes no sense, sand can't jump." Well, of course not. But tiny little harmless creatures can magnificently blend with the golden brown environments of beaches, scuttling and jumping along whilst being so small to the point of resembling sand particles. They move quickly and often in an overall unnoticeable manner, giving off the 'jumping sand' illusion. These creatures are referred to as Sand Fleas.

What are Sand Fleas?

Although the name suggests otherwise, sand fleas are actually not insects (or fleas) at all, but rather they are crustaceans. They are more closely related to lobsters, crabs, and crayfish than actual fleas or ticks. Alternative names are sand crab, sand bug, beach flea, sand hopper and sand fiddlers, although the names with 'fleas' are misleading as they are not actually fleas. They acquire a barrel-shaped body which measures between 1/2 inches to 1 inch long. Female sand fleas are larger than their opposite, growing up to 2 inches long compared to male sand fleas, which measure up to 3/4 inches long. Young sand fleas are usually dark-brown to black, with a small minority appearing to have a slightly tan colour. Adult sand fleas are even lighter, often appearing translucent, making them difficult to see with the naked eye. These colours provide the camouflage they require to survive in their sandy habitats. These crustaceans have 5 sets of tiny legs which allows them to dig into the sand and/or paddle through the water for escape and search for nutrition.

Why is it a Myth?

There is some ongoing debate as to whether or not sand fleas are ACTUALLY fleas, meaning they are capable of harming humans. The definition of 'sand fleas' lies in the public perception of what counts as a sand flea, which is pretty much anything that moves in the sand, according to Nancy Hinkle, Ph.D, a professor at University of Georgia’s Department of Entomology. However the popular concept suggests that when people are referring to sand fleas, they are actually referring to the small, harmless, sand crustaceans (they don't bite!), rather than actual harmful fleas like the chigoe flea (they bite).

Sand Flea Anatomy

Like fish, sand fleas have gills which allow them to breathe, and they also need oxygenated water to survive. They have a telson (the last part of the abdomen; tail fan which they may use to escape or swim in water) located at the end of their underbelly, where bright-orange eggs on a female sand flea may be seen. The telson, while providing motion features, also offers some protection of the soft underbelly of sand fleas. They also have a hard exoskeleton.

Will it Bite?

Sand fleas are harmless crustaceans, and blood is not a source of energy/food for them. They mainly feed on organic debris including seaweed, and they do so by lifting their antennae-like feeders to catch the debris as the waves recede back into the ocean. 'True' sand fleas are the crustaceans, rather than the actual fleas such as chigoe, and therefore they are often harmless. Chigoe fleas, on the other hand, can burrow into human skin to lay eggs, as well as bite humans and transmit diseases. The burrowing of the skin as well as bites are not considered to be the worst part, rather the aftermaths of the bites and burrowing are deemed as scarier, as burrowed and bitten skin can leave you vulnerable to severe infections.


Sand fleas are not to be confused with the sand crustaceans, as they differ greatly in terms of their effects on humans; one bites, one doesn't. Regardless, the general public often refers to the sand crustaceans as sand fleas, but they are completely harmless and often unnoticeable! If you think you've been bitten by an actual sand flea, such as the chigoe, make sure to disinfect the affected area, as well as refer to your doctor if pain at the site persists for long periods.

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