Congruences

morphological adaptations in different individuals of the same species that foster closer functional ties and ensure the integrity of the species.

Congruences arise in individuals of different generations (for example, in mammals, between the extraembryonic membranes of the embryo and the uterine mucosa), different sexes (for example, in insects, the mutual adaptation of the copulative apparatus of male and female), the same sex (for example, in male ruminants, the “tournament” horns, which prevent the males from killing one another in battles for the female), and colonial forms, which have different functions and different structures (for example, in hydroids, the gastrozooids and dactylozooids).