It is clearly written in zoology textbooks that all birds have a cloaca, that is, an extension of the back of the intestine, in which the excretory ducts and the ducts of the reproductive system merge together. It was an axiom, but what was the surprise of those who, while gutting the carcass of an Indian duck, discovered an incomprehensible organ. Every curious person will want to know what it is. It turns out that some species of birds have copulatory organs.
What is this?
Before we move on to birds, we need to understand what copulatory organs are. The name itself comes from the Latin word "copula", which translates as a connection. Only representatives of the animal world with internal fertilization have such organs. And they are in both males and females. Their second name is copulatory organs. Males need them to inject sperm into the body of their chosen one.
Of the animals known to science, some worms, most mollusks, some arthropods and fish, amphibians, have such organs,almost all reptiles and mammals, some representatives of birds.
Which birds have them?
In most birds, the process of fertilization occurs when the male presses his cloaca against the cloaca of the female. Another way of mating is called cloacal kissing. In this case, birds do not have copulatory organs. But there are a small number of species in which the section of the cloaca turns inside out, forming an unpaired copulatory organ. In birds, it enters the body of the female during mating.
But in what species can this anatomical miracle be found? First of all, in ostriches, as well as in some species of ducks and geese, and also in tinamou. As for the size, the record holder here is the Argentine duck, in which the length of the organ exceeds the size of the duck itself and can reach 45 cm! Why so many? Just to brag. And already the female chooses the right size for herself.
In geese, it is worm-shaped and twisted into a spiral. The length can vary from 7 to 15 cm. An erection occurs only from the flow of lymph, and not from blood, as in mammals.
In roosters and turkeys, this organ is represented by an elevation called the follus, which protrudes outward only at the time of erection. So there are exceptions to every rule, and not all birds have cloacal fertilization as we are taught in school.
