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How to Distinguish Between Male & Female Crabs

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Being able to tell your male crabs from your female crabs can come in handy. The difficulty of determining the gender of a crab can range from quite easy to moderately challenging, depending on the type of crabs you are trying to sex. The larger the crab is, the easier it is to determine the gender. Handle your pet crab gently and try not to unnecessarily stress him out as you determine his gender. Also be sure to avoid getting pinched by his claws.

Step 1

Look at the crab's claws. In some species of crabs, like the fiddler crab, males will have one claw that is significantly larger than the other. If you are trying to tell the gender of blue crabs by their claws, then it is fairly easy. Blue crab males have blue claws while the females have red-tipped claws.

Step 2

Pick up your crab from the rear and gently turn him over. Do not shake him or pull on his legs. Avoid his claws.

Step 3

Look at the underside of your crab. If "he" is in fact a he, then you will notice a triangular shape on the rear section of the bottom of his underside. If "he" turns out to be a she, then you will notice a broad, round marking in the same area that does not have such a triangular appearance.