REPRODUCTION 35I 



In form, structure and position, the Cetacean penis is very similar to 

 that of bulls and other male ruminants (rams, goats, stags, etc.) in all of 

 which this organ is completely hidden beneath the abdominal skin, and 

 in all of which it resembles a thin, hard rope. (The pizzle which was 

 formerly used for flogging was, in fact, a bull's penis.) In whales and 

 dolphins, the penis, at its base, consists of two arms (the crura) which are 

 attached to the pelvic bones. The arms fuse into the very long rope-like 

 body which is cylindrical or oval in cross-section. In large Rorquals, it 

 can be as long as ten feet with a diameter of up to i foot (Fig. 192). A 

 slit, just posterior to the umbilicus, allows the anterior part of the penis, 

 which is surrounded by a fold of the abdominal skin, to be pushed out. 

 In whales, as in ruminants, the retraction of the penis into the penis slit 

 is brought about by a pair of strap-like muscles (the retractores penis). 

 When the penis is retracted and flaccid, the organ assumes an S-shaped 

 position inside the skin, but when the muscles (which are attached to the 

 top of the S) slacken, the penis may become erect, due partly to the 

 elasticity of the particularly hard and tough connective tissue of its shaft, 

 and partly to turgidity caused by the sudden influx of blood into a mesh- 

 work of blood spaces (cavernous spaces) . 



If we look at the penis of any mammal in cross-section, we see that, 

 inside its thick wall, it contains special spongy tissue (the corpus cavewosum 

 penis), in which small arterioles carry blood to the venous sinuses. By 

 distension of the arterioles and simultaneous contraction of the efferent 

 venules, large quantities of blood can be stored in the organ, with the 

 result that it lengthens and becomes tumescent, a prerequisite for copula- 

 tion. A similar spongy structure (the corpus spongiosum) surrounds the 

 urethra, which lies in a separate groove, and is also found under the skin 

 of the anterior shaft which, though it has a simple pointed tip in most 

 Cetaceans, can yet be compared with the rounded glans of other mammals. 

 While the spongy tissue of the outer skin and that surrounding the urethra 

 consists entirely of blood vessels, the central corpus cavernosum penis of 

 Cetaceans is riddled with strands of tough and elastic connective tissue, 

 with a consequent reduction of cavernous (spongy) tissue proper. The 

 penis of whales and dolphins (like that of ruminants) becomes erect not so 

 much through an influx of blood, as through the elasticity of its tough 

 tissue. On the other hand, the penis of odd-toed ungulates (i.e. horses). 

 Carnivores, and apes, becomes tumescent primarily through the influx 

 of blood, and consequently their corpora cavernosa penis consist mainly 

 of cavernous tissue (Fig. 193). Cetaceans have no os penis. 



The correspondence between the genital organs of male Cetaceans and 

 even-toed ungulates makes us suspect, straight away, that there is a 

 similarity in the way they copulate. We all know that bulls, rams, or stags 



