Sperm Storage and Cryptic Female Choice

The above video from Science News shows two male cuttlefish violently competing for a single female to mate with. The second "intruder" male arrives to the scene after the first male mates with the female. The two males engage in a violent, inky fight, and the female eventually flees the scene. One explanation for why the first male remains to fend off the intruder, even after successfully mating with the female, is that female cuttlefish store sperm. A female can store packets of male sperm from multiple matings. This suggests that even after mating with a female, a male might hang around to prevent other males from mating with her, as seen in the video. This increases the chance that the male's sperm is selected for fertilization, instead of another male's genetic material, and helps him secure his paternity.

Cuttlefish represent just one type of animal that is capable of sperm storage. Various species of insects, birds, and reptiles are also capable of this. In fact, females of such species can select which male's sperm they want to fertilize their eggs in a process called "cryptic female choice." This allows females to select sperm that can increase offspring quality and number.