Birds do it, bees do it, penguins do it, and orangutans do it. By having sex and giving birth to offspring, animals ensure that their species will survive into the next generation. And in this quest for survival, animals go to great lengths.

Some animal mating techniques may strike you as strange or gross, but to the animals themselves, these practices are essential. Animals with the best strategies for choosing mates and making babies ensure that their species live on. Without animal sex, there would be no animal life.