Ghost crabs (genus Ocypode) comprise 22 different species and they are commonly also called `Sand crabs`. The scientific name Ocypode has got Greek origin and means swift-footed. Generally, Ghost crabs are semi-terrestrial crabs and dig deep burrows in intertidal zones of sand. They can be found in all subtropical and tropical regions worldwide. The name Ghost crab comes from their swift movements over sand during darkness and their whitish-colored claws.
Appearance of Ghost crabs
All species of Ghost crabs are characterized by the following three characteristics:
- One claw is always larger than the other one, and both claws are pale colored (often white). The smaller claw serves for picking up food and the larger one for crushing it.
- They have thick and elongated eyestalks, which they can fold below the carapace.
- Body shape is box-like.
Additionally, Ghost crabs can adapt their whole body coloring to the surrounding sand colors and the time of the day, which further reinforces its name of Ghost crab. A more detailed description of Ghost crab taxonomy, appearance, and behavior can be found at this link.
How to find Ghost crab holes on the beach?
During the day, a Ghost crab normally stays in its resting chamber, which is located at the lower end of the entrance tunnel. These entrance tunnels have a diameter of about 1 ½ – 1 ¾ inches / 32 – 38 mm and lead at an angle of about 45 degrees down to the chamber.
Depending on the increasing size of the residing crab, the depth of the chamber below the surface is also increasing. But generally, these chambers are located from 60 cm to 1 m / 2 – 3 feet below the surface. As the crab tries to have the resting chamber partly covered with saltwater, the further inland the entrance hole, the bigger the crab inside.
Holes on the surface with a residing crab can be easily spotted by the freshly ejected sand grains, as can be seen from the attached photos above.
Digging for Ghost crabs
When a live hole was found, first – and most importantly – it had to be filled with dry sand from the surface. This ensures that the crab will not be able to take flight. Additionally, when digging, the light-colored dry sand marks the position of the hole. Otherwise, it would be difficult to find the right direction to the resting chamber.
When digging, either a small shovel or a piece of flat wood will help to save energy. When arriving at the resting chamber, the Ghost crab will stick out its larger claw for protection. This helps to locate its legs and carapace to get a good grip on it.
How to hold Ghost crabs in hand?
Different crab species require different ways of holding them safely. Ghost crabs are relatively small in size and can turn their nippers far down their belly area. Therefore, never hold a Ghost crab from behind, but always sideward of the carapace.
Incorrect grip, resulting in a good nip
Correct grip
How to store and transport Ghost crabs?
After catching, it is safest to hold these crabs in a strong fabric bag with a drawstring. When opening this drawstring for adding another inhabitant, great care has to be taken not to lose any of the existing crabs. As they are just waiting behind the string to get out. They are ingenious in escaping from any not safely closed container. And a plastic bag will be easily torn into pieces by them.
Use of Ghost crabs
These crabs are of a small size and therefore only have a small amount of meat on them. In Thailand, they are a prized add-on ingredient to Som Tam – the famous Thai green Mango salad.
After cooking, the carapace, gills, and intestines will be removed. The remains are getting washed, smashed, and added into Som Tam. The pictures above show a different crab species used for this purpose – but Ghost crabs are used the same way.
Ghost crabs are also sold at some markets on the seaside, where they are offered cooked and spiced up as an ingredient to other dishes.
Lessons learned from Ghost Crabs:
- Although Ghost crabs are very swift-footed, they can be caught in their resting chamber during daytime.
- Before digging them up, the entrance tunnel has to be filled with dry sand.
- Never hold a Ghost crab like a mud crab. A Ghost crab has to be held on its sides, not from behind.
- After catching them, store them safely in a container, where they will not be able to escape.
