Many birds do not have penises, and mate by touching genital openings -- called a "cloacal kiss". But some species of duck and ostriches do have a penis.

The longest bird penis discovered belongs to the Argentine lake duck (Oxyura vittata), measured at around 42.5cm, an astonishing dimension matches the length of an adult male, and compares to the length of an ostrich penis. If the Argentine lake duck were human, we could boast 5 - 6-foot penises!

Back to whales again! In general, cetaceans have no protruding udders like cows. Whale mammaries are two long and fairly flat organs inclined to each other at a slight angle. Their tips are not far from the umbilicus, and the average dimensions in "resting" Rorqual cows are about 7ft. by 2 ft. 6 in. by 2 1/4 in.

As a precursor to more complex forms of bisexual reproduction a number of simple plant and animal species learned to "con jugate", i.e. to exchange genetic material between the individuals within a species in such a way that the offspring could be distinct from either parent. The classic example among plants is Pandorina, a 16-cell species: the cells are loosely attached and each has a pair of flagella, of protoplasmic whips, for the purpose of locomotion through the water. To reproduce, the cells separate and fuse with the similar cells from another

Many fish appear to take pleasure in kissing: this is particularly the case with "ornamental" fish. Wendt remarks that "The couples use their lips in the ceremonies of courtship in a surprisingly human manner." One particular type of labyrinth fish is known as the "kissing gurami" In this species the enthusiasm for the kiss is such that one such act may last as much as twenty-five minutes. Doubtless human kisses can exceed this duration but such achievements must be rare.

Coitus of the longest duration in mammals occurs in mink and sable. Unlike coitus in other species, there is no "locking" of the genitals, but when intromission has once been achieved it is maintained for very long periods: several ejaculations can occur with rests between them. Timed matings of the sable have lasted for as long as 8 hours from the moment of original insertion until the time of withdrawal. One authority (Marshall's "Physiology of Reproduction") gives coitus in the mink, as in the ferret, as "prolonged" and usually lasting for 30 to 40

There is startling variation in the character of penises (penes) throughout the animal kingdom. Apart from size variation, already noted, shapes and colouring vary enormously. Insect and reptilian penises are often equipped with spines, corrugations, knobs, hooks, etc., to secure the female once insertion has taken place. If a copulating pair of insects or snakes are forcibly separated then either the male or the female may be irreparably damaged. The genital organs of the male may be torn off or the female may be terribly lacerated. Disengagement, following

This remarkable creature is a worm (Diplozoon paradoxum - the "paradoxical double animal"). It lives on the gills of carp-like fish and as a hermaphrodite it is theoretically capable of mating with itself. In the course of maturing two of these parasitic worms grow together in the middle of their bodies and become effective Siamese twins joined together until death. The vagina of each half of the hermaphrodite becomes permanently linked to the sperm duct of the other half. William Bolsche termed the beast "a love monstrosity, an erotic Briareus with

Most of us tend to associate masturbatory activities with the genitals, though a few of us may also think of such bodily parts as the nipples or anus.

We have already seen that chimps do not take very long over coitus; a number of other mammals are even swifter. Slijper has noted that bulls, rams, and stags copulate "with astonishing rapidity" and that the whole process lasts no more than a few seconds. Horses manage a few minutes. Whales too are said to copulate very rapidly, a circumstance no doubt conditioned by their ungainly mass. In some descriptions of whale coitus the

Whales, as may be expected, generate the greatest volume of seminal discharge and the substance is sometimes discernable in the sea after a male has ejaculated.

Among domesticated mammals the boar is usually cited as producing the greatest volume of ejaculate. The volume of fluid averages around 200ml, but the range is from 100 ml to 500 ml (the upper limit representing a generous cupful).