Following the link in the post here, http://www.aquaticquotient.com/forum...1&postcount=10, you should come across this:
Just for general information, pleopods are appendages of crustaceans used for swimming, also known as swimmerets, not the legs used for walking. The first or two pairs of pleopods in the male crayfish, also referred to as gonopods, are modified to perform internal fertilisation in the female.Originally Posted by www.petshrimp.com
So you should look out for something similar as shown in the photos with arrows in the following link.
Hope that helps.