|This article does not cite any references or sources. (May 2007)|
An aedeagus (plural aedeagi) is a reproductive organ of male insects through which they secrete sperm from the testes during copulation with a female insect. Very loosely, it can be thought of as the insect equivalent of a mammal's penis, though the matter is actually quite more complex.
The aedeagus is part of the male's abdomen, which is the hindmost of the three major body sections of an insect. The pair of testes of the insect are connected to the aedeagus through the genital ducts. The aedeagus is part of the male insect's phallus, a complex and often species-specific arrangement of more or less sclerotized (hardened) flaps and hooks which also includes in some species the valvae (clasper), which are paired organs which help the male hold on to the female during copulation. During copulation, the aedeagus connects with the ovipore of a female.
The sperm of arthropods is not passed to the female as liquid with free-swimming spermatozoa, but contains capsules called spermatophores in which the actual spermatozoa are enclosed. In addition to the spermatophores, in some species the aedeagus also discharges a spermatophylax, a ball of nutritious secretions to aid the female in producing offspring.
- Pedipalp#Spider pedipalps for spermatophore transfer in arachnids