Intromittent organ

The sexually mature male typically deposits semen from the palpal bulb onto a specially woven silken mat, then sucks the emission into his pedipalps.

[citation needed] In Solifugae, sperm transfer is also indirect; the male deposits a spermatophore on the ground, picks it up in his chelicerae, then inserts it into the female's genital opening.

In most millipedes, sperm transfer is performed by one or two pair of modified legs called gonopods, which are often on the seventh body segment.

For example, some insects, most notoriously the Cimicidae and some Strepsiptera, practise traumatic insemination, in which the intromittent organ pierces the abdominal wall and the semen is deposited into the hemocoel.

[6] In male members of Chondrichthyes (sharks and rays), as well as now-extinct placoderms, the pelvic fins bear specialized claspers.

In males, the anal fin is shaped into a grooved, rod-shaped organ called a gonopodium used to deliver sperm to females.

[8] In lizards and snakes, males possess paired hemipenes, each of which is usually grooved to allow sperm transport and spiny or rough at the tip to allow firm attachment to the female.

[26] Waterfowl intromittent organs range greatly in length, are often characterized by surface elaborations (both spines and grooves), and at times spiral counter-clockwise.

Waterfowl intromittent organ variation is most likely due to an intersexual arms race resulting from a mating system in which forced extra-pair copulations are frequent.