Sanibel Sea School Blog

Ghost Crabs

April 5, 2021

By Emily White

If you’re sitting on the beach on a quiet day and almost everything is still, you might see a small, boxy, sandy- or grayish-white crab skitter by. However, you would probably have more luck at night- that’s when the Atlantic ghost crabs, or Ocypode quadrata, are most likely to be out and about.

When night falls, it is time for the ghost crab to hunt. By looking for food after dark, it will avoid predators like seabirds. One of the few predators that this 2-inch crab has to worry about at night are raccoons – otherwise, it is a top predator within the filter-feeding food chain, and its only worry is seeking out clams, insects, detritus and other snacks. It can swivel its large, club-like eyestalks 360 degrees to watch for prey, and if it needs to get moving quickly, it can run sideways at speeds up to 10mph.

When the sun begins to rise, the ghost crab will construct a new burrow, up to four feet under the sand, just wide enough to fit itself inside. It will plug up its burrow and stay inside until night falls once more.

This crab also needs to make sure it visits the water occasionally in order to moisten its gills – ghost crabs use their gills to absorb oxygen from the air, and if they don’t keep their gills moistened, they wouldn’t be able to breath. They don’t even necessarily need to be in the water- ghost crabs have fine hairs on their legs that wick water from damp sand up into the crab’s gills.

If you’re ever taking a walk along the shore at night, watch the ground- there might be a ghost crab lurking right under your feet!

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