Spermatophore

Definition

A capsule, sac, or discrete package containing spermatozoa produced by the male and transferred to the female during copulation or courtship. In arthropods, spermatophores may be delivered directly via an intromittent organ such as the aedeagus (common in beetles and many insects), deposited on a substrate for female pickup (typical of arachnids including spiders and scorpions), or incorporated into complex courtship displays. Some spermatophores contain accessory materials—nutrients serving as nuptial gifts (e.g., bush crickets), defensive compounds (e.g., pyrrolizidine alkaloids in the moth Utetheisa ornatrix), or structural proteins—while others are sperm-only packets. The form, placement, and composition of spermatophores are taxonomically diagnostic and subject to sexual selection.

Etymology

From Greek sperma (seed, sperm) + -phoros (bearing)

Example

Male scorpions deposit a spermatophore on the ground, then guide the female over it so she can take up the sperm packet through her genital opening; in contrast, male leaf insects (Phylliidae) transfer the spermatophore directly during copulation, visible as a white spherical structure at the posterior of the mating pair.

Synonyms

• sperm ampulla

Related Terms

• Aedeagus
• spermatheca
• Nuptial gift
• indirect sperm transfer
• direct sperm transfer
• cryptic female choice
• Sexual selection

Usage Notes

Distinguish from continuous fluid ejaculate; a spermatophore is a discrete, often structured package. The presence/absence of spermatophores and their mode of transfer (direct versus indirect) are key characters in arachnid and insect systematics. In some literature, 'spermatophore' is used loosely for any sperm-containing structure, but specialists reserve it for encapsulated or packaged sperm distinct from seminal fluid.