Footprints in the Sand - Eco Trail
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Crustaceans

Four species of crab make their homes on Pensacola Beach: the blue crab, the hermit crab, the horseshoe crab, and the sand fiddler crab.

Along with crab, a variety of shrimp are found in the Gulf year-round. Commonly known as brown, white, and pink, these shrimp from along the Southeastern U.S. coast are collectively known as “Gulf Shrimp.” They live in shallow water, and both brown and pink shrimp move to deeper, saltier waters as they grow. Almost 85% of pink shrimp from the U.S. is harvested from the west coast of Florida.

Sand Fiddler Crab

The sand fiddler crab is distinguished by its single large "fiddler" claw. It uses this claw not for obtaining food but for advertising to potential mates and intimidating rivals. It moves in herds of thousands to feed.

The sand fiddler crab’s larger claw can be much bigger than the rest of the crab’s body. It is common for males to lose their larger claw in battles. When this happens, the claw regenerates and the opposite claw begins to enlarge, eventually becoming the new dominant claw. It is distinguished from similar species by the smoothness of the inside of its claws.

Crustaceans at Pensacola Beach

Blue Crabs

The blue crab’s most distinguishing feature is its hind legs, known as “swimmerets.” It whirls these legs like the blades of a helicopter to move through the water. Males have blue claws; females have red.

The female blue crab lays up to two million eggs in a single brood, and a single female can produce more than eight million eggs in her lifetime. The blue crab’s coloring stems from a number of pigments in its shell, but when the crab is cooked, these pigments break down, turning it red-orange. Blue crab fisheries exist all along the Atlantic coast of the United States, most prominently in Chesapeake Bay, where tens of millions of blue crabs are harvested every year.

Hermit Crabs

The hermit crab uses salvaged empty seashells to protect its body. As it grows, it will need to find a larger shell and abandon the previous one. Several hermit crab species use "vacancy chains" to find new shells – when a new, bigger shell becomes available, hermit crabs gather around it and line up from largest to smallest. When the largest crab moves into the new shell, the second biggest crab moves into the newly vacated shell, and so on.

Though hermit crabs have been known to take on a large variety of different shells, they most commonly inhabit the discarded shells of dead snails. Hermit crabs may fight or kill a competitor to gain access to the shell they favor. Despite this, and despite their name, they are social animals that function best in groups. Like the horseshoe crab, hermit crabs are not true crabs and are more closely related to lobsters. They are popular pets and can live as long as 23 years in an aquarium if properly treated.

Horseshoe Crabs

The horseshoe crab is not a true crab—it has no close living relatives, but it is most similar to a spider. It has existed for more than 360 million years, making it one of the oldest creatures on earth. The horseshoe crab has survived multiple extinction events and is thus considered a “living fossil.”

The entire body of the horseshoe crab is protected by a hard shell. It has two primary compound eyes and seven secondary simple eyes, two of which are on the underside. Beneath the carapace, it looks quite similar to a large spider. It has five pairs of legs for walking, swimming, and moving food into the mouth. Its long, straight, rigid tail can be used to flip itself over if turned upside down. Unlike almost all vertebrates, the horseshoe crab does not have hemoglobin in its blood but, instead, uses hemocyanin to carry oxygen. Because of the copper present in hemocyanin, its blood is blue. It is sometimes used as bait when fishing for eels.

Brown Shrimp

Brown shrimp have 10 walking legs and five pairs of swimming legs, and their tails are green or red in color and usually have a reddish-purple band. They can reach up to 7 inches in length, depending on factors such as water temperature. Juvenile and adult shrimp feed on worms, algae, microscopic animals, and various kinds of organic debris. They are prey to blue crabs, among other sea life.

White Shrimp

The first commercially important shrimp in the U.S., with fisheries dating back to 1709, the white shrimp is prized for its sweet, tender meat. They commonly inhabit coastal areas out to about 100 feet offshore, and they are often found in association with brown shrimp. White shrimp are not grooved like other shrimp, and they have long antennae that can reach 2.5-3 times longer than their body length.

Pink Shrimp

The west coast of Florida is home to nearly 85 percent of the pink shrimp harvested in the U.S. They are usually found on sand, sand-shell, or coral-mud bottoms, and they are most abundant during the winter. Their shells have a dark colored spot on each side and a dark blue band. Some of the food sources of juvenile and adult pink shrimp are copepods, small mollusks, algae, and slime molds.