copulate

Copulation refers to the act of sexual union between two individuals, typically for the purpose of reproduction. The term derives from the Latin copulare, meaning to join together. In biology, copulation is commonly used to describe internal fertilization that occurs when a male’s reproductive organ is introduced into a female’s reproductive tract and sperm are deposited or transferred. It is a central component of sexual reproduction in many animals, including most mammals, birds, reptiles, and some invertebrates.

However, fertilization is not universal through copulation. In many fishes, amphibians, and some invertebrates, fertilization can be external or achieved by other mechanisms, and the word copulation may be less applicable. Some species use specialized structures or mating rituals to align partners and transfer sperm. The specifics of copulatory behavior—such as duration, frequency, and the cues that trigger it—vary widely across taxa and ecological contexts.

Copulation is often embedded in broader mating behaviors that include courtship, mating opportunities, and postcopulatory processes such as sperm competition and selective fertilization. Reproductive strategies influence how often copulation occurs and how it fits into the species’ lifecycle.

In humans and many primates, copulation generally refers to sexual intercourse and can occur for reproductive, social, or pleasure-related reasons. Ethical considerations, consent, and health are central in human contexts, while in the natural world the focus is on understanding the diversity of reproductive strategies and their ecological and evolutionary implications.