Masked Crab- Western Isles
Corystes cassivelanus
The masked crab or sand crab as it is often called - seen here in The Western Isles - and on The Isle of Lewis and The Isle of Harris has an elongated reddish brown to yellow in colour carapace.
It sometimes has features patterns that look like a face and of course easily identified by the long pointed tube.
The bristly antennae are much longer than the carapace. The first pair of walking limbs or 'pereopods' have pincer and are about twice the length of the carapace in males, (the same length as the carapace in females)
Pointed Tube - Antennae
The masked crabs easily identified by the fact that the two antennae between its eyes are modified into a tube to inhale sea water for it to breathe. Its most obvious feature is of course this long pair of hairy antennae which form the pointed tube, which point directly forwards from between its eyes. These antennae are capable of locking together to form a snorkel which is used to obtain oxygenated sea water . The tip of the tube protrudes through the surface of the sand enabling the crab to breathe. The tube is invaluable to the crab which spends most of its time buried beneath the sand looking for worms, bivalves and tiny crustaceans.
Burrows Backwards into The Sand
This crab burrows backwards into the sans, not a Sideways Walk Not all crabs walk sideways. The Masked Crab burrows backwards into the sand to hide.
The Mask Crab can rebury itself very quickly
If the crab is removed from the sand it can quickly rebury itself by rapidly digging with its legs.
Habitat
Masked crabs live buried in the sand on lower shores of the coastline - however occasionally they can be found sitting on the surface at low tide
Washed Up After Storms
The mask crab is often washed up in large numbers after storms. Dead Masked Crabs are washed up on sandy beaches, but to watch them alive you may have to dig down into the sand at a very low tide.
Food
The masked crab feeds on sand-living invertebrates, worms, bivalves and small crustaceans.
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