Sex chromosomes influence physical differences between male and female animals, such as feather patterns in mandarin ducks. In most animals, sex chromosomes help determine whether an individual develops as a male or female. Sexes of some animals, such as most male arachnids, lack a second sex chromosome entirely. These chromosomes contribute to the physical differences between males and females.
The sex lives of animals: A rough guide | New Scientist
From an evolutionary and biological perspective, animals are driven to have sex in order to procreate. But there is a lot more to sexual relations between animals. Animal sex is at least as strange and varied as human sex. A male might copulate with many females. And female animals of many species can be choosy, too. Homosexuality is common.
Fourteen Fun Facts About Love and Sex in the Animal Kingdom
By Michael Marshall. The urge to reproduce, to pass on our genes to a new generation, is one of the most powerful in our lives. This is equally true of the bewildering variety of animals with whom we share the planet.
Dating apps have reduced the ritual of human coupling down to a swipe. Creatures of all sorts have evolved some pretty spectacular strategies to woo their mates and ensure their genes carry on. Here are just a few examples of extreme courtship and copulation that put us tech-savvy humans to shame. Like humans, giraffes undergo cycles of fertility.