Ghost crabs are a common sight on sandy beaches across tropical and subtropical regions worldwide. These fascinating crustaceans are named for their pale coloration and their tendency to be most active during the night, making them seem to vanish like ghosts. As semi-terrestrial creatures, they spend most of their lives on land, frequently seen darting across the shoreline or retreating into their burrows. Their appearance is well-suited to their coastal environment, allowing them to blend seamlessly with their surroundings.
General Body Description
Ghost crabs exhibit a body shape that is box-like or squarish when viewed from above. Their carapace, or shell, can measure up to 3 inches in width, with males larger than females. These crabs are small, ranging from 2 to 3 inches in length and weighing between 0.53 to 2.5 ounces. Their shell may also appear somewhat translucent in certain species.
The coloration of most ghost crabs is pale, ranging from yellowish or cream to off-white, tan, or grayish, which provides effective camouflage against sandy backgrounds. Ghost crabs can change their body coloration to match their immediate surroundings and even the time of day, adapting their pigment distribution over time. While many are pale, some species, like the painted ghost crab (Ocypode gaudichaudii), display brighter hues, such as red-orange with sandy dots.
Prominent Sensory Organs
A striking feature of ghost crabs is their prominent sensory organs, particularly their eyes. Their eyes are located on elongated, thick, and club-shaped stalks that stand straight up from their carapace. In some species, these eyestalks may be topped with distinctive “horns” or stiles.
The corneas, the visual parts of their eyes, are large and occupy at least half of the eyestalk. This specialized structure grants ghost crabs a 360-degree field of vision, important for detecting both predators and prey in their open beach habitats. When threatened, these crabs can rapidly retract their eyestalks into protective grooves on their shell.
Claws and Legs
Ghost crabs have eight walking legs and two forelimbs, known as chelipeds, which terminate in claws. Their jointed legs allow them to move quickly, reaching up to 10 miles per hour across the sand. They use all eight walking legs for locomotion, but can rely on their first and second pairs for rapid bursts of movement. These legs are covered with fine hairs, or setae.
One claw is typically larger than the other. This asymmetry is present in both male and female ghost crabs, although it is less pronounced compared to the exaggerated claws seen in male fiddler crabs. The larger claw is often more rounded. These claws are often white, featuring small bumps or nodules and serrated margins.