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!
This matter is as complex as it is interesting, so put your mind in low gear and hold on…
Earth worms are hermaphrodites. Counting from the front, the worm’s male sex cells lie in segments 10 and 11. From here the sperm pass through sperm ducts to two male genital openings on the bottom of segment 15. On segments 9 and 10 there are two minuscule sacs called sperm receptacles, or pores, where, during earthworm sex, sperm are deposited. However, this is not where eggs are produced. The egg-producing ovaries reside in segment 13, from which eggs are released through the female pores into egg sacs in segment 14. Finally, there’s a rubbery, arm-band-like thing covering the worm’s body from segments 31 or 32 to 37, and this is called the clitellum.
Now, when two earthworms mate, they line up next to one another with their “heads” pointing in opposite directions. The clitellum of one worm lies opposite segments 9-11 of the other, which, you’ll remember, contain the male parts. The worms now secrete tremendous amounts of mucus, until each is enclosed in a slime tube extending from segment 9 to the rear end of the clitellum at segment 37. Now sperm are ejaculated from segment 15 and carried backward in tubes formed by grooves in the body touching the slime tube and the sperm pass to the sperm receptacles on segments 9 and 10 of the other worm.
Then the earthworms go their different ways. Sex is done. However, that is not to say that eggs have been fertilized, because they haven’t. It’s just that now, in each worm’s sperm receptacles, there are sperm from the other worm.
The next step in producing baby earthworms comes when the earthworm is by itself. Its clitellum secretes a second mucous ring that slides forward over the worm’s body. When the ring passes the openings in segment 14, several ripe eggs leave the body and stick to the ring. The ring keeps moving forward until it passes the sperm receptacles in segments 9 and 10, and here sperm come into contact with eggs. Finally, within the mucous ring, the eggs are fertilized.
Now the ring containing the fertilized eggs slips off the worm’s “head,” seals at both ends, and becomes a sort of cocoon, which is left lying in the soil. Ultimately the eggs hatch and tiny worms escape from the mucous ring, into the soil.
The end.
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.
The Argentine Blue-bill or Argentine Lake Duck (Oxyura vittata) is a small South American  duck with an average penis length of 8 inches (20cm) – that is longer than a human who se average penis size is 6 inches.
The longest recorded penis of the duck was a a remarkable 42.5 cm (17 inches) long penis (central photo).
This is the longest relative penis in vertebrates, animals related with us.
Biologists believe that the remarkable size of this penis may have evolved in response to competitive pressure in these highly promiscuous species, removing sperm from previous matings in the manner of a bottlebrush.
The male bedbugs don’t even bother with the female’s sex organs. Instead, a male bedbug uses its scimitar-like sexual organ to impale the female bedbug’s body and deposit his sperm.
Scientists even have a name for this sort of thing: “traumatic insemination.”
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).
