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.

It will come as no surprise to those interested in the animal world as a whole that human beings did not invent the idea of group sexual activity.

Arthropods, for example, frequently engage in such practices, as do various more highly developed species. Cetaceans- porpoises, for example - are particularly keen on various group sex activities, and so are their larger brothers and sisters, the whales. Of Grey Whales H. Wendt noted in "The Sex Life of Animals": -

It is estimated that breast-feeding began more than 200 million years ago, the time of the first mammals (Which laid eggs and hatched them). Subsequently no less than 18,000 different species of mammals evolved.

The kangaroo has the unique ability to produce two types of milk from two teats for young of different ages. It is curious that the number of teats or nipples varies throughout the mammalian world. The horse and elephant, for

As human beings we are accustomed to thinking of males having one penis and two testes and females having one vagina and two ovaries (though there are exceptions to this among men and women). However, a number of animals generally quite primitive species - boast a greater quantity of sex organs. For instance the medusa of the water-living obelia, which looks like a tiny bell-shaped piece of clear jelly, has no less than four testes in the male and four ovaries in the female. Eggs and sperm are simply shed into the sea-water where fertilisation takes

Most mammalian vaginas are more or less the same in overall configuration: they basically comprise a smoothish lubricated channel to allow penile insertion and subsequent parturition. Some vaginas are however exceptional. One such is the vagina in the female hippopotamus, coming equipped as it does with 10 to 19 transverse interlocking fibrous ridges. The ridges at the upper end of the vagina are the most pronounced, resembling heavy corrugations. Similar, though less pronounced, corrugations are discernible in the vagina of pig and warthog. In

A number of female insects eat their husbands during the coital act. It has been argued that in the praying mantis, for example, the male can only copulate successfully when half his head has been eaten away - something to do with releasing nervous inhibitions! It has been pointed out that mantises will mate satisfactorily in the terrarium if the female's terrible forelimbs are tied before she is introduced to the male - so perhaps cannibalism is not

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