2018-04-01 / Features


Scratch that with knowledge

Robert Turpin Robert Turpin The focus of last month’s article on the Florida pompano, a highlyprized fish (quarry) of local surf fishermen, leads to the subject of this month’s article. One of the primary reasons that Florida pompano inhabit the surf zone of our local Gulf of Mexico beaches is the abundance of their favorite prey: the humble sand flea.

Although commonly called “sand flea,” this creature is only distantly related to fleas. Its scientific name is Emerita talpoida.

The species name talpoida is derived from the Latin “talpa,” meaning “mole,” and it is so named for its behavior of digging into the sand. When identified with the other crabs in its Order, it is easy to understand how it got its other common name: mole crab.

The Latin name of the genus Emerita means “retired female professor.” One can only speculate how this name was derived.

Sand fleas are relatively small (1/4 to 1 ½ inches) egg-shaped crabs. Their body surface, shape and color are designed for digging and blending into the sand in the “swash zone” of local Gulf beaches.

They may also be found along bay beaches near Pensacola Pass. They can only burrow into sand that is saturated or covered by at least a thin layer of water. As waves wash over the swash zone, sand fleas burrow backwards into the sand until only their eyes and antennae remain exposed to feed and gain sensory information. If threatened, they can burrow several inches into soaked sand.

Sand fleas’ diets consists of plankton and detritus (small pieces of the remains of plants and animals) that wash up and down the swash zone with every breaking wave.

Of their two pairs of antennae, one pair is feather-shaped and specialized for harvesting food from the waves.

Sand fleas are most abundant in the lower part of the swash zone, moving up and down the beach face with the rising and falling tides to maintain their optimum feeding positions.

During the colder winter months, sand fleas migrate off the beaches into warmer, deeper water.

Sand fleas are an important ecological link between plankton and detritus and pompano, red and black drum and other fishes along Gulf beaches.

Sand fleas become reproductively mature in their first year of life and may live two to three years. Like many other crabs, female sand fleas carry the orange mass of eggs attached to specialized abdominal appendages. When the eggs are ready to hatch, they are released into the receding waves and are carried into the open Gulf as planktonic larvae.

Sand flea larvae remain planktonic for several months, growing and molting until they achieve their adult burrowing body form. It is remarkable that the variable movements of water masses deliver planktonic sand fleas back to the beaches after months of drifting in the open waters of the Gulf of Mexico.

Juvenile sand fleas, about the size of a grain of rice, sometimes arrive on the beaches en masse. I have observed hundreds in a double-handful of sand. Shorebirds are often indicators of this abundance as they feast on the new recruits.

Although sand fleas are one of the most abundant macroinvertebrates on our Gulf beaches, many people are unaware of their presence as they walk by. Sand fleas can detect the vibrations of approaching footsteps and burrow farther into the saturated sand.

Many locals, especially shore anglers, can easily spot the tell-tale signs as receding waves pass over feeding sand fleas. Specialized metal baskets called “sand flea rakes” are used to catch sand fleas for bait. Local specialty bait and tackle shops usually carry sand fleas in the spring and summer.

Children sometimes catch sand fleas while digging in the sand. I fondly remember my daughters’ laughter when their hands were tickled by sand fleas trying to burrow between their fingers.

When they were old enough, I bought them miniature sand flea rakes. Not only did I receive “free” bait, but we all enjoyed countless hours of their exploration and discovery of buried treasure along our beaches.

Having lived on the coast of northwest Florida for more than a halfcentury, I find there is one aspect of sand fleas with which I am not yet familiar: culinary. I have eaten just about every other edible organism from local waterways, but I have not yet eaten sand fleas. I recall my good friend and culinary adventurer Chef Dan Dunn describing their taste. I have accepted an invitation from Chef Dunn to attend his next “Sand Flea Fry” and will report my findings in a future column. Stay tuned …

Sand fleas are also excellent indicators of environmental conditions along the coast. Effects of oil spills, beach re-nourishment and other events may be elucidated by the abundance and the condition of sand flea populations. Their planktonic larval stages likely mitigate localized, small-scale impacts to sand flea populations.

Natural variation in water currents may also drastically affect local sand flea abundance from year to year. Long-term studies of sand fleas and other near-shore benthic species will help us understand and protect our valuable Gulf beaches for future generations.

Return to top