The horned ghost crab (Ocypode ceratophthalmus) is a remarkable creature that dwells along the sandy coasts of the Indian and Pacific Oceans. They get their name ghost crabs because they can disappear very quickly, like a ghost. Their nocturnal behaviour and sandy colour (blending with the surroundings) also contribute to the name.
All the burrows you see on the beach are made by these crabs. Some of them are as deep as 1.3 meters! These burrows serve as a bioindicator—fewer the burrows on beaches, greater the wildlife disruption due to human activities.
One of the peculiar characteristics of the ghost crabs is their ability to change their colour (camouflage) to match their surroundings; they have also been shown to change colour based on the time of the day (circadian rhythm).
The ghost crabs are scavengers and munch on the remains of dead animals. But they also prey on worms, snails, prawns, sea cucumbers, and even other small crabs. Sometimes they display a rather unusual behaviour—cannibalism.
These crabs boast a distinct appearance. Their body is box-shaped, above which sits a pair of large eyes on short stalks. The eye stalks can rotate 360 degrees. Each eye has a “horn” protruding up, hence the name horned crab. The eye stalks can be folded into grooves when the crabs burrow into the sand. The ghost crabs have exceptional vision, which comes in handy when they retreat into their burrows to escape from intruders and harsh sunlight.
Two strong claws help the crabs crack open clams and also burrow deep into the sand. Ten legs, built for speed, make the ghost crabs the fastest in the crab world. Fewer the legs the crabs use, faster they are. At their fastest, the ghost crabs use only the first two pairs of legs.
Being able to live outside the water for extended periods, these crabs often burrow in wet sand to moisten their gills. And hair-like structures on their legs help absorb saltwater from the sand.
When it's time for mating, the male crab showcases its talents by performing tricks and displays to woo females. The impressed female ventures into the male’s burrow, where breeding occurs. The female carries thousands of eggs within her. After fertilization, she releases the eggs into the sea. The tiny larvae develop in the ocean and return to the shores after a couple of months, completing their remarkable life cycle.
There are about 20 species of ghost crabs around the world, each with unique characteristics. These intriguing creatures, on average, live for about three years.
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