Sperm from different species vary in size and shape. Bull and human sperm, for example, have paddle-shaped heads, rodent sperm have hook-shaped heads, and the heads of chicken sperm are spindle-shaped and almost difficult to distinguish from the midpiece. The images shown below of rat, bull and chicken sperm are all at the same magnification.
Male hedgehogs use a vaginal plug during sex to prevent other male conquests of their mate.
Otters are not as cute as they look. Marine biologists studying  what the sea otters of Monterey Bay have recorded  rape, murder  and necrophilia!
Male sea otters have been seen grabbing seal pups and then shagging them until they drown. They even keep the dead seal pups for up to seven days afterwards for their sordid sex games.
Sea otter females don’t always come off well  in the hands of the rough males either -
more than 10% deaths of sea otters were  thought to be from mating trauma.
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If you are a bonobo, or pygmy chimpanzee, the noisier the nookie, the higher social class one of the participants is.
The lower-ranked partner in bonobo couples always made the sex noises, researchers at St Andrews university in Scotland have found.
The crying out generally increased with the partner’s social standing, regardless of whether that partner was male or female, implying they were ‘in’ with Mr or Mrs Popular.
‘Female bonobos achieve power by forming coalitions with other females as well as males, so getting powerful female friends, and advertising it, matters,’ said primatologist Dr Zanna Clay.
‘Like humans, sex among bonobos is not only used for reproduction, it is also important in other ways, such as friendship and bonding, and keeping close to powerful others.’
Female bonobos gave out copulation calls during sex with other females, reaffirming the belief the noises serve a much broader social role than just expressing pleasure.
Researchers spent a year in the Congo studying the primates.
The tapir has one of the longest penis to body size ratios of any animal. When erect it is often longer than 45 cm!
Despite their immense size gorillas have very small sexual organs. Their penis on average is just a mere 2 inches. In some African countries, it’s an insult to tell someone they’re hung like a gorilla.
Being the biggest mammals on the planet its not surprising that whales also have the largest penis.
With the biggest animal the blue whale having the biggest of all. The largest measured blue whale penis reached 2.4 m (8 feet).
To court a female during the very short mating season (a mere 6-12 hours per yea!), a male porcupine stands up on his hind legs, and sprays her with a huge stream of urine from as far as 6 feet away drenching his would-be paramour from head to foot!
If the female isn’t impressed, she’ll scream and shake off the urine. But, if she is ready, then she’ll rear up to expose her quill-less underbelly and let the male mount her from the behind (that’s the only safe position for porcupines!). Once mating begins, the female is insatiable: she forces the male to mate many times until he is thoroughly exhausted. If he gets tired too quickly, she will leave him for another male!
Female hyenas has a pseudopenis, basically an enlarged clitoris, that they can erect at will. To mate, the meeker male has to insert his penis into her pseudopenis.
After being separated for a few hours, spotted hyenas engage in “greeting” displays that entail lifting their legs and exposing their erect pseudopenises for inspection. Subordinate females often initiate greetings and this is the only known case of an erection being a submissive gesture.
