Black cats are black because of high levels of eumelanin pigment, and the gene that produces it is dominant. A kitten only needs one black gene from a parent to have a black coat.
Almost all frogs fertilize the eggs outside of the female's body. The male holds the female around the waist in a mating hug called amplexus. He fertilizes the eggs as the female lays them.
Nipples don’t have muscle inside them — the erection of the nipple happens because of tiny smooth muscle fibers in the areola that contract in response to cold, touch, or sexual arousal.
According to Greek culture, the color blue is said to ward off their ancient superstition of “the evil eye.” To put this in practice, some Greek people choose to wear a blue charm necklace or bracelet for protection.
An erection is a vascular process where the corpora cavernosa fill with blood, increasing in length and thickness, often initiated by the parasympathetic nervous system.
