How to Tell the Gender of Sharks

Female sharks, for the most part, are bigger than males. Despite being mostly independent creatures, sharks occasionally display social patterns. So if you see a picture of a couple of sharks together, their relative sizes might provide some hints of their genders if they're not all the same sex. Male sharks generally look much trimmer and sleeker. Females tend to be a lot more rotund.

Sexing a shark based on size alone isn't easy if you don't have any reference for comparison. Look for claspers. Male sharks' pelvin fins are equipped with pairs of slender long claspers. These claspers jut out from the foundations of the pelvic fins, and are necessary for mating. The claspers of immature male sharks are a lot more subtle than those of adults, but they're still clearly visible.

Female sharks don't have claspers, so if you're looking around the pelvic fins, you'll see only their cloacas. These cavities are necessary not only for breeding, but also for the elimination of waste. The males also have cloacas.

Although there aren't many other physical differences between male and female sharks, their reproductive behaviors sometimes help signify their genders. During mating, male sharks frequently bite their partners -- their way of latching onto them. Because of this, female sharks often have scarring on their bodies. This isn't the case for blue sharks (Prionace glauca), luckily for their females. Female blue sharks have significantly denser skin than the males, an adaptation to accommodate the biting.