Mating plug
Gelatinous secretion used in the mating of some species / From Wikipedia, the free encyclopedia
A mating plug, also known as a copulation plug,[1] sperm plug, vaginal plug, or sphragis (Latin, from Greek σφραγίς sphragis, "a seal"), is a gelatinous secretion used in the mating of some species. It is deposited by a male into a female genital tract, such as the vagina, and later hardens into a plug or glues the tract together.[2][3] While females can expel the plugs afterwards, the male's sperm still gets a time advantage in getting to the egg, which is often the deciding factor in fertilization.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Mating_plug.jpg/320px-Mating_plug.jpg)
The mating plug plays an important role in sperm competition and may serve as an alternative and more advantageous strategy to active mate guarding.[4] In some species, such a passive mate-guarding strategy may reduce selection on large male size.[5] Such a strategy may be advantageous because it would allow a male to increase reproductive success by spending more time pursuing new female mates rather than active mate guarding.[5]