Terrestrial animal Terrestrial animal The term terrestrial is typically applied for species that live primarily on the ground, in contrast to arboreal species, which live primarily in trees. There are other less common terms that apply to specific groups of terrestrial animals: Terrestrial invasion is one of the most important events in the history of life. Terrestrial lineages evolved in several animal phyla, among which vertebrates, arthropods, and mollusks are representatives of more successful groups of terrestrial animals. Terrestrial animals do not form a unified clade; rather, they share only the fact that they live on land. The transition from an aquatic
Homosexual behavior in animals injuries as males lack the female counteradaptive spermalege structure. Males produce alarm pheromones to reduce such homosexual mating. Homosexual behavior in animals Homosexual behavior in animals is sexual behavior among non-human species that is interpreted as homosexual or bisexual. This may include same-sex sexual activity, courtship, affection, pair bonding, and parenting among same-sex animal pairs. Research indicates that various forms of this are found in every major geographic region and every major animal group. The sexual behavior of non-human animals takes many different forms, even within the same species, though homosexual behavior is best known from social species. Scientists perceive