Rabbit physiology is suited to escaping predators and surviving in various habitats, living either alone or in groups in nests or burrows. As prey animals, rabbits are constantly aware of their surroundings, having a wide field of vision and ears with high surface area to detect potential predators. The ears of a rabbit are essential for thermoregulation and contain a high density of blood vessels. The bone structure of a rabbit’s hind legs, which is longer than that of the fore legs, allows for quick hopping, which is beneficial for escaping predators and can provide powerful kicks if captured. Rabbits are typically nocturnal and often sleep with their eyes open. They reproduce quickly, having short pregnancies, large litters of four to twelve kits, and no particular mating season; however, the mortality rate of rabbit embryos is high, and there exist several widespread diseases that affect rabbits, such as rabbit hemorrhagic disease and myxomatosis. In some regions, especially Australia, rabbits have caused ecological problems and are regarded as a pest.