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The “Ghosts” of the Night
By: Donna M. McDine
As you walk along the beach, the sand feels crunchy under your feet and you may even hear a click-clack sound. What in the world can that noise be? You shine your flashlight down at your feet and discover the beach is covered with crabs.
 When darkness arrives, the crabs emerge from their burrows in the sand to gather food and to wash water over their gills for oxygen. They feed on live prey, including mole crabs, coquina clams, turtle hatchlings, and other small animals. Ghost crabs also feed on dead flesh and beach debris.
Ocypode quadrata, which means “fleet of foot,” is the Greek scientific name for ghost crabs. They are most active at night, hence their name. They are mainly found on beaches that are not heavily used by people, ranging from Rhode Island to Brazil, including the West Indies and Bermuda. They must be careful when they go in the water to wet their gills. This is the best time for fish to snap them up. On land, raccoons and seagulls prey on ghost crabs.
Scientists believe that ghost crabs are in the midst of an evolutionary change. They are in the process of evolving from a sea animal to a future as a land animal. Many of their crab relatives have a thick protective shell, but ghost crabs do not possess this type of shell, nor are their pinching claws very powerful. Their “periscope” eyes that see 360 degrees provide protection from predators like sea gulls, dogs, and children. They dig burrows to hide from birds, because they cannot see directly up. The grooves in the front of their shells are where they can retract their eye stalks for added protection.
Ghost crabs burrow themselves back into the sand as dawn approaches. Ghost crabs have the ability to move quite fast, as much as six feet per second or ten miles per hour. Not only can they run sideways, they are capable of moving forward and backward.
Ghost crabs do scamper across the beach from time to time during the day. But between their swift locomotion and their perfect color of gray-white or pale yellow that serves as their camouflage in the sand, the human eye must be quick to see them.
Now that you know all about ghost crabs, go ahead and grab a flashlight, a camera, and an adult and have fun looking for them. If you are fast, you can get close enough to take a quick picture. The flash stuns them for a moment before they get their senses back and scurry away. Photograph Copyright © 2008 Donna M. McDine
Copyright © 2008 by Donna M. McDine |
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