Common Ghost Crab (Ocypode Cordimanus)

Australia has six known species, of Ghost crabs.

These little crabs are so good at camouflaging with the sand, thus their name, making it difficult to see them during the day, if for whatever reason, they happen to leave their burrow.

Ghost crabs are found on open sandy beaches, where they live in their immaculate burrows, (some known to be more than 4 feet), near the intertidal zone, in the dry sand. They are nocturnal and remain in their burrows to keep cool during the day and warm during the winter.

They can hold oxygen in their air sacs for about six weeks, handy when you hide and live under the sand.

During the night, Ghost crabs, fix and repair their burrow and feed on a variety of plant and animal debris that has been washed ashore.  These omnivores can even catch insects in mid-air; due to their 360 degree vision, that allows them to see in any direction.

Ghost crabs breathe through gills, which they keep moist at all times, by various methods, such as taking the moisture out of damp sand.

An interesting thing to do whilst relaxing on a quiet beach is to listen for the Ghost crabs, very distinct, bubbling sounds! They use their gill chambers to produce bubbly sounds.

The female Ghost crab incubates 1000’s of eggs inside her flap, and once matured, these eggs become marine larvae.  Mum releases her offspring into the sea, where they remain for about two months before returning back to the shore.

Did you know that the Ghost crab’s burrows are regarded as valuable ecological indicators for quickly assessing the impact of human disturbance on beach habitats?  And, they can travel across the sand up to 10 to 15km/hr.  Yes, they are fast movers, and that is why they are so hard to catch.  Isn’t it interesting that their generic name is ocypode, which in Greek means, fast -foot.

I remember one day while I was drying off after a swim, I decided to read and relax, I saw movement in the corner of my eye, and I spied a tiny Ghost crab, well camouflaged with the sand, right next to a small burrow. I went to pick it up and it quickly fled into its hole. I started digging but there was no way in this dry sand that I could find it.  The crab had dug down so deep; apparently, they can construct long pathed tunnels, to who knows where… hence another reason for the name, Ghost crab.

Of course, afterward I realised I should not have dug into his home, all that work would have been destroyed.  I vowed not to do that again.  We need to be sensitive to the ecosystem that in some environments are quite sensitive, the softer our footprint is, in the natural environment,  the better for us all; flora, fauna, marine life, and us humans.

By M.A.Loveday ND (Lecturer and Guide on Wildlife/ Lover of Nature)

References: PDF Brazilian Journal of Oceanography 57(2):149-152 / Coastal Habitat Awareness Program –OCCI / Ghost crab a tool for rapid assessment of human impacts on exposed sandy beaches. ELSEVIER. Biological Conservation. F.Barros 97 (2001) 399-404 / Personal observations.

 

 

 

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