All about lobster > How can you tell the difference between male and female lobsters?

Female lobsters are usually wider in the upper dorsal tail region (allowing room in the tail to store the premature eggs) but the main characteristic is found under its abdomen. Turn the lobster over and you'll see appendices like little fins. There are five pairs: the first pair (nearest the head), located at the junction of the abdomen and thorax, is different from the others and allows you to differentiate between males and females.