Have you ever wondered which animals getfreakiest between    the sheets?  
    The answer to that is, literally, probably bed bugs.  
    But what about octopus? Why do lobsters shoot urine from their    faces? And what is "penis fencing"?  
    If these are the questions keeping you up at night, read on.  
    The sport of fencing  where opponents spar using modified    swords or "foils"  is thought to have emergedaround the    14th or 15th centuries.  
    But in nature, it's existedfar longer.  
    Pseudobiceros is a genus of flatworm flat,    soft-bodied,aquatic animals  that also engagesin    fencing.  
    But unlike the human sport, flatworms don't    use "foils". They use their penises.  
    The other difference is thatin"penis fencing", the    loser ends up pregnant.  
    Pseudobicerosare hermaphrodites  the majority    of the body mass of species like the Persian carpet flatworm    (Pseudobiceros bedfordi) comprises both testes and    ovaries.  
    During battle, each assailant exists as a kind of    Schrdinger's flatworm,    whereinbothanimalsare simultaneously the    potential father andmother.  
    The first penetration decides their fate.  
    A successful strikealmost anywhere on the bodysees    sperm injected into the skin, where it will migrate through    pores tofertilise the eggs of the disappointed    mother-to-be.  
    Once the deed is done, the "father"exits the scene to    fence again, while the expectant mother will gestate their    unwelcomeclutchfor around 10 days.  
    In the world of flatworms,carrying fertilised eggs is    laborious, and gestation putsa temporary hiatus on    seeking opportunities to further spreadone's genes. So    flatworms will fight ferociously to avoid that fate.  
    Here's a sentence you probably didn't think you'd read today:    female lobsters urinate out ofholesin their    faceto show a male they're interested in mating.  
    And that's only the start of their freakiness.  
    The urine, which is expelled from holes known as nephropores at the base of    the lobsters' second antennae, contain pheromones to convey    her gender and potentialsuitability as a mate.  
    "They have theseremarkable,weirdly orientated    organs which arethe equivalent of our kidneys basically,"    says Tomer Ventura, a scientist working in crustacean    aquaculture at the University of the Sunshine Coast.  
    "They're situated pretty much in theircheeks under the    antennae."  
    Dr Ventura, who has pioneeredgene-silencing technology    that can be used in commercial aquaculture to produce a    single-sex population of crustaceans, says thatin wild    lobsters, the dominant male sits in a den from where he vets    potential suitors.  
    To make sure he cops a full blast of the spicypheromone    mix, the female uses her gills to create a current, wafting it    in his general direction.  
      "She squirts her urine directly into the den where the      dominant male is," Dr Ventura says.    
    If he's picking up what she's putting down, she'll be invited    inside, where he'll provide protection    whilesheremoves her carapace her shell     replacing it with a fresher, cleaner model.  
    The courting ritualhas mostly been studied in the    American lobster, Homarus americanus, and while it    might be the sort of behaviour you'd expect from American    crustaceans, it's also true of our own spiny lobster, among    others, Dr Ventura says.  
    He says in lobsters, the male produces a spermatophore  a    capsule of sperm, which also contains a protective gelatinous    matrixthat sets like a sticky concrete on contact with    water.  
    The female carries that spermatophore around with her until    she's ready to release her eggs.  
    "The female releases virtually millions of eggs while scraping    the surface of the spermatophore to reveal the intact sperm.  
    "[At the same time she's]curling her tail to release that    cement that sticks the fertilised eggs onto her swimming legs    in the tail."  
    At this point it's probably safest toassume    there'surine involved unlessstated otherwise.  
    In the case of giraffes, males will smell the hindquarters of    the female, often flaring his upper lip in what is known as a    "flehman response".  
    While it has the appearance of a grimace, the flehman response    draws air into the vomeronasal organ  an olfactory sense organ    in the nasal cavity above the roof of the mouth  which assists    in the detection ofpheromones.  
    He's checking to see if she's ovulating and ready to mate.  
    But if he's not convinced, the male will encourage her to    urinate by rubbing her hindquarters.  
    He'll then taste her urine, and if he picks up the signals he's    after, will follow her around in the hopes of mating.  
    In the wild, he won't be the only one showing an    interestthough, and will need to fight off other males    using his huge neck to pummel his rivals, while attempting to    plunge his ossicones  horn-like appendages on his head  into    their flesh.  
    If you've ever had bed bugs and thought, "gross, I'm sharing my    bed with bugs", strap in.  
    Humans and bed bugs have a long history.  
    Research suggests bed bugs    were originally bat specialists, feeding on the winged    creatures in caves in Africa.  
    But as our ancestors moved into caves millions of years ago,    bed bugs decided we were a tastier option and shifted their    allegiance.  
    As humans spread from Africa and across Eurasia, we took the    bed bugs with us.  
    We can't really begrudge the bed bugs for feeding on our    bloodthough. They need all the energy they can get    formating.  
    Adult bed bugs become most active during witching hour     between about midnight and 5am.  
    They locate their sleeping hosts by detecting exhaled CO2 and    body heat, and once fed, are in the mood for love.  
    Cue Barry White? Not quite.  
    The male bed bug stabs his reproductive organ through the right    side of the female's body wallinto what is called her    Organ of Berlese.  
    The male's sperm enters the body cavity, migrates to her    ovaries and fertilises her eggs.  
    Females may be stabbed multiple times by different males during    one outing, and will retreat to recover, lesttheir    traumatic mating prove fatal.  
    How many eggs and offspring she is capable of producing depends    on how much blood of yours  she's able to consume in    her lifetime of between 100 and 300 days.  
    Of course octopus are on the list. They've got eight legs, nine    brains and only a year or so to use them.  
    Research has observed at least one female octopus strangling    her partnerduring copulation.  
    Another study observed a smallmale Octopus    cyanea, also known as big blue octopus, mating with a    larger female 12 times over a three-and-a-half-hour period    while she foraged for food in Palau, Micronesia.  
    Perhaps fed up, hungry or both, on his 13th attempt, she    suffocated him, took him back to her den, and "spent two days    cannibalising him".  
    Michael Amor, a research assistant in the aquatic    zoologydepartment at the Western Australian    Museum,says it's probably not a great surprise that    octopus sometimes eat their mates.  
      "They're not the most social beings. Theremight not be      that [emotional] barrier to feeling you shouldn't eat your      neighbour," Dr Amor said.    
    Research published last    yearalso showed female octopuses throwing shells and    other debris at males to ward off their unwanted advances.  
    It probably makes sense that a female should be    discerningabout whofathersher children. It's    typically her only shot at reproduction, and the egg-brooding    period can be especially traumatic.  
    For most shallow-water octopus species, once the deed is done    the female sits on her eggs for a period of one to three    months.  
    Even in these instances, females have been known to eat their    own arms rather than leave the nest in search of food,    according to Dr Amor.  
    But in deeper water, where conditions areharsher and    colder, thingscan stretch out much longer.  
    Back in 2014, research published in    PLOSdetailed the exploits ofa female deep-sea    octopus  Graneledone boreopacifica in 1,397    metres of water on a sloping wall in the Submarine Canyon off    central California.  
    Using a remotely operated vehicle, scientists first encountered    the female over a period of a few weeks, first without eggs and    then shortly after having laid them.  
    Seizing the opportunity to measure the brooding time of a    deep-sea octopus, the researchers endeavoured to monitor how    long she sat on her clutch.  
    Four years later, they were still watching.  
    The eggs had continued to grow, whilst she was diminishing in    size and had becomepale, with cloudy eyes and slack skin.  
    On the researchers'final visit, after 53 months, only the    "tattered remnants of empty egg capsules" remained in her    place.  
    It was the longest-known egg-brooding period for any animal.  
    Olaf Meynecke spent years researching mud crabs and says after    what he's seen, he can no longer eat the    feistycrustaceans.  
    For Dr Meynecke, a marine ecologist at Griffith University who    now studies whales, it wasn'tso much how they mate as    what they eat.  
    "They're literally turning rotten meat into their own meat,    whichwe then love to eat," he says.  
    On the bow-chicka-wow-wowscale, mud crabs are about    mid-range, but there's some research, including some conducted    by Dr Meynecke,that earns them the final place on this    list.  
    Typically mud crabs hang around coastal, mangrove-lined    waterways in the tropics and sub-tropics.  
    When it comes to mating, the male jumps on top of the female,    and will basically hitch a ride around with her for a few days.  
    In some instances, the males have been known to pick up moulted    females and carry themaroundfor several days while    mating.  
    Similar to lobsters, the male deposits a spermatophore capsule    that the female carries with her until she's ready to fertilise    her eggs.  
    Not known to be great long-distance swimmers, the females    typically hang around their estuaries for most of their life    cycle.  
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    However, some large, gravid females have been found 50    kilometres or more offshore.  
    Dr Meynecke's team wanted to see if they were returning back to    their estuaries after such an epic journey.  
    "Wetaggedsomeof those females in the Logan    River [in south-east Queensland]," he said.  
    "They were acoustic tags  about $800 tags on eachcrab."  
    Unfortunately for Dr Meynecke's hip pocket, the crabs never    returned.  
    The hypothesis is thata certain proportion of older    females crabs make a one-way journey for a final reproductive    effort, culminating in the release of their fertilised eggs    into the East Australia Currentto disperse their genes    far and wide.  
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The weirdest and wildest mating rituals in the animal world, from bed bugs to giraffes - ABC News