Following on from yesterday’s post on Seaweed, today I am concentrating on the humble Shore Crab and another that we found a Masked Crab.
Shore Crab
The Shore Crab is is the most common crab that you will find when Rockpooling or lifting Seaweed and Stones on the beach.
“Carcinus maenas” the “Shore Crab” also known as “Green Shore Crab” can be found on the majority of beaches in the British Isles.
Shore Crabs can grow between 1 to 4 inches. Its shell/carapace typically has three blunt teeth between its eyes, however on smaller Shore Crabs the may be indistinct. On each side of the shell past the eyes there are five sharper teeth.
The way that you can tell a male and female crab apart is down to the number of joints on its tail. Yes a crab has a tail, which is folded under its belly and you can see it when you turn them over. Carefully of course and especially if you are holding a larger crab with big pincers!
A male has a five jointed tail, whereas a female has seven joints.
As with most crabs there are 4 pairs of legs and a set of pincers. If you look at the back legs you will see that they are flatter and used to help the crab swim.
Masked Crab
We did find another species called a “Masked Crab” or “Corystes cassivelanus”. A distinctive shape with long antenna at the front.
The Masked Crab is between 1 and 1.5 inches long. The marking on the shell can look like a human face.
Males have pinchers twice the length of the body whereas the females are not longer then their body. With three teeth marked in the shell on either side of the carapace.
This was a female and was laiden with eggs so she went straight back where we found her.
Once you have found and looked at the crab, put it back where you found it and put any Seaweed and rocks back in place.
Happy Rockpooling.
Sparrowhawk Bushcraft 