Animal parents: from self sacrifice to murder

In the animal kingdom, reproduction is a vast and interesting topic with many different methods having evolved.  Take for example the frog mums who let tadpoles develop in their tummy and then have to regurgitate them.  Or any one of the marsupials who give birth to jellybean sized young who then have to struggle across mum to find her pouch where lies safety and food.  I’ve written before about kangaroos and how females are essentially a baby making conveyor belt with young at various stages ‘on the go’.

Birth might sound difficult for the kangaroo but I’m betting the hyena is looking on wistfully… Female hyenas experience horrific births.  Their birth canal is a funny shape, it’s longer than most similar sized mammals and the umbilical cord is short.  This means there is a higher risk of asphyxiation, but it gets worse.  The baby’s head is too big to pass through the clitoris (hyenas have an unusual genital makeup and urination, fertilisation and birthing are all carried out through the clitoris) so when a mother gives birth, the clitoris tears.  Not just painful, this can be deadly, with estimates of over 10% of females dying the first time they give birth and more than half of cubs being stillborn.  Things don’t get much better for those cubs that survive either… they tend to arrive in litters of two and the one that is born first tends to kill the second within minutes of birth.

Not necessarily a difficult birth, but the frilled shark has to suffer pregnancy for over three years…  The babies grow a frustrating ½ inch per month and don’t emerge into the water until they reach 1 ½ to 2 feet long…

On land, the longest pregnancy falls to elephants who have to endure almost two years of pregnancy before a baby pops out but thankfully, once little ellie has arrived, the whole herd play a role in raising it.  Similarly, sea lions have collective arrangements with a nursery so they can drop off the pups and then head out to feed.  This rota system works well for sea lions but this communal approach isn’t the case for all animals.  In many species, mum and dad don’t actually engage in parenting and in others, the burden falls on just one parent.  And in some cases, this burden can literally kill mum.

Self sacrificing parents include octopus mums who guard their eggs for several months, starving during this time as they can’t leave them.  Once they hatch, the mother dies.  As sad as this is, it pales in comparison to the desert spider.  When the female desert spider lays an egg sac, her insides start to liquefy.  Once her babies hatch, she regurgitates her innards for her young to eat and nine days later, only a husk remains.

When desert spider lays an egg sac, her tissues start to degrade until the spiderlings hatch. Once this happens, she regurgitates her own liquefied insides for the babies to eat.  9 days later they finish up her innards and then head off into the world, leaving her husk behind…

For orangutans the substantial workload falls to mum who has to spend 8 years raising her babies, longer than any other animal single parent.

Whilst pregnancy and childrearing might be tough for mum, not all dads are hands off.  Indeed, in some cases, its only the male who’s involved in child rearing – the male rhea receives eggs from various females to incubate and rear and the same is true for the cassowary.

Indeed, this system – where the males look after the young from several females, and females spread their brood between several males – is common, especially among fish.
– Olivia Judson

Childcare arrangements vary throughout the natural world with some parents having no involvement, some species specialising in single parenthood and others working together to raise their children.  The type of gestation affects the possible roles for parents.  In mammals for example, where the fetus develops in the womb, there isn’t a lot that the males can do.  For birds however, dad can sit on the eggs and provide food for the chicks just as well as mum can.

Looking at a couple of egg examples, we can see there are different levels of involvement and different roles the parents can play.  The spraying characid is a fish that lays its eggs out of water – the female leaps out of water and lays eggs, then the male leaps out and fertilises them, an act which is repeated until about 300 eggs have been laid.  For the next three days, dad has to stay with them and splash the eggs with his tail to keep them from drying out.

For some leeches, parenting is the basic guarding eggs from predators but for African leeches, a kangaroo style approach has been adopted and they carry their young in a pouch, and for another type of leech, the young are glued to their parents tummy.

But moving onto mammals, we find the Dayak fruit bat where both mum and dad produce milk, taking shared responsibility for nursing their young.  Djungarian hamster males are also devoted to their babies.  They “forage for seeds which they stuff into their pouches in their cheeks; on arriving back at the burrow, they unload their cargo by pushing on the pouches with their forepaws so that seeds stream forth” (Judson).  In addition to finding the food, the males help in the birth process, acting as a midwife and helping the pups out.  They also open their airways and lick them clean, even going so far as to eat the placenta.  Male marmosets also carry out a similar role and will go on to play an active role in childrearing.

Hornbills are another devoted parent.  The female climbs into a nest in a tree and seals up the entrance so that there is only space for her beak.  She is then reliant on her partner to bring her food whilst she incubates the chicks.  Once they are born, the father must bring food for the whole family until it is time for them to emerge.  Overall, the female spends as much as 137 days cooped up in the nest.

But there’s always two sides to a story…  And on the flip side to these dedicated parents, we find infanticide.

In many species where fatherhood is clear, males will kill offspring that is not there.  Infanticide gets pesky children out of the way so that dad doesn’t have to spend resources, time and energy on raising them.  They also do this because without children around, the females get in season and thus he can get her pregnant and have children of his own.  Squirrels, wolves and primates are some of the creatures that engage in this behaviour and about 34% of gorilla infant deaths and 64% of languar infant deaths are down to infanticide (Bondar).

In species which are particularly prone to infanticide, females have evolved a number of countermeasures such as keeping babies in burrows or pouches so that males can’t get to them but there are times when even mum can’t keep their baby alive.

“In rodents, an increased incidence of infanticide is observed for males during periods of food deprivation, and for females during periods of lactation (which confers high energetic demands).”
– Carin Bondar

In coot and moorhen families, who have a large number of chicks at once, parents tend to feed the closest mouth, but if one chick becomes particularly demanding, the parents will try and discourage it by picking it up and shaking it, sometimes killing it.

In some animals, a male having a mistress can lead to the death of the children, the ultimate in wicked stepmothers!  The mistress will often murder the wife’s children and if the opportunity arises, vice versa.

“In both the house sparrow and the great reed warbler, for example, a male with two mates will help only the female whose clutch hatches first, so to ensure herself of male assistance, a savvy mistress will smash all the wife’s eggs.”
– Olivia Judson

Murder isn’t only a risk that comes from your parents; the sand shark practices intrauterine cannibalism, the biggest fetus gobbles up its embryonic siblings whilst in the womb. Whilst an extreme example, siblingcide is not uncommon in the animal kingdom.  In many invertebrates, cannibalism is the way to get rid of your pesky brothers and sisters and thus not only do you get a good meal, you also guarantee increased access to resources going forward.  Whilst not so extreme, eagles and hyenas also kill their siblings, although they wait until after birth.

Of course there are many other interesting births and parenting techniques in the animal kingdom and I could never do any more than scrape the surface here but if these exmaples have whet your appetite, try checking out some of the links below and look into seahorses, that well known fully involved dad!

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Let’s do it like they do on the Discovery Channel…

Whilst my last post focused on sex primarily in a reproductive context, animals have sex for many reasons, just like humans do.  However, “for decades, biologists, anthropologists and psychologists have suppressed inconvenient evidence of homosexual behaviour among the human and nonhuman animals they observed” (Julien Dugnoille).

I’m going to start by looking at same sex activity as it’s one clear thread of evidence that not all animal sex is for reproduction.

There are many more bisexual animals than we tend to think and note I’m saying bisexual because often the animals aren’t solely engaging in same sex activity (which I’m going to say because same sex sex is a mouthful!).  Often, they are also having sex with the opposite sex when the opportunities arise.  The BBC also discusses whether we can claim some animals are homosexual as opposed to bisexual.

Ultimately, these are human enforced labels and as Eric Anderson says:

“Animals don’t do sexual identity.  They just do sex.”

You’ve quite possibly heard about the ‘gay’ penguins in a zoo.  They coupled up and started building their nest and sitting on rocks.  When the zoo realised what was going on, they placed an egg from a female penguin who was struggling to care for it in the nest.  The male penguins successfully incubated and raised the chick.

Same sex dolphins can become partners for life engaging in sexual behaviour, for example males can have a temporary female relationship but will return to the initial male partner afterwards.  Further, two male couples can join up to become a foursome.  One theory is that it helps to have a companion when feeding and resting because they can look out for danger.

Some male greylag geese pair up and when it’s time to raise children, they find a female and raise them together as a trio.  Some don’t but research shows the advantage of a trio; there is better defence against predators, the female has a higher social rank and better chance of survival and the female has more time to devote to her chicks because two males are helping.  After the chicks are raised, the males stay together whilst the female leaves.

In a reverse make up, roughly 2% of oystercatcher breeding groups are made up of two females and one male.  Additionally, up to a quarter of black swan families include parents of the same sex (Scientific American) and in some bird species, males steal eggs from females and raise them in same-sex unions.

Whilst these examples might feel like the exception to the rule, observers have witnessed as many as 1500 species of wild and captive animals engaging in same sex activity.

“Homosexual behaviours is surprisingly common in their animal kingdom.  It may be adaptive- helping animals to get along, maintain fecundity and protect their young.”
– Emily Driscoll, ScientificAmerican.com

Moving on from same sex activity to other non reproductive sexual activity, we find types of fruit bats who engage in oral sex, both female on male and male on female.  There is also masturbation and attempts to mate with the dead…

But what is all this sexual activity about?  Obviously, some sex is about reproduction, but pleasure, bonding and keeping the peace are all reasons for engaging in sex.

Bonding can be important for group species and strong bonds can be very helpful when facing off rivals or seeking protection from other group members.  This bond is also important in maintaining a strong group dynamic and sexual activities can diffuse social tensions.  Another type of bond is that of a parenting couple who may engage in sexual activity to maintain their bond whilst raising their young.

It’s interesting to look at an example, the bonobo.  Bonobos use sex to greet each other, to resolve conflict and for pleasure.  They engage in mutual masturbation, oral sex and penis fencing and are in general a very peaceful species.  Perhaps humans would be more chilled out if we had more sex?

But lets take a second to focus back on masturbation.  As well as humans, many other primates engage in masturbation and this can range from simple stimulation with their hands through to using twigs and leaves and other inanimate objects.  Females have been observed inserting objects into their vaginas and one male orangutan created his own sex toy:

“In one display of sexual ingenuity, a male orangutan created his own ‘sex toy’ using a large leaf, through which he poked a hole with his finger.  He then proceeded to thrust his erect penis through the hole for additional stimulation.”
– Carin Bondar

Sexual activity may also help some animals to reiterate their social hierarchy and may allow individuals to climb the ranks.

In some cases, animals may engage in non reproductive sexual activities such as same sex sex in order to gain sexual experience.  It’s interesting to note that it seems that same sex activity appears to be more common in captivity (although that could just be because its easier to observe), possibly because of a lack of alternative options and greater need for stress release.  In a similar way, you tend to find higher than ‘natural’ rates of same sex activity in prisons.

Time for another example!  Most penguins are not monogamous but it is by turning to Adelie penguins that we really get our eyes opened.  A scientific paper from 1915 had been hidden away for years, labelled not for publication and when it was rediscovered in 2009, it became clear why scientists of the time were reluctant to publicise the observations.

“They were ‘gangs of hooligan cocks’ whose ‘passions seem to have passed beyond their control’ and whose ‘constant acts of depravity’ run the gamut of masturbation, recreational sex and homosexual behaviour to gang rape, necrophilia and paedophilia.  Chicks were ‘sexually misused by these hooligans’, including one who ‘misused it before the very eyes of its parent’.  Strayed chicks were crushed and ‘very often suffer indignity and death at the hands of these hooligan cocks’.”
– Lucy Cooke quoting Dr George Murray Levick

Whilst this all sounds incredibly shocking, there is an explanation.  Adelies get together in October, flooded with hormones and only a few weeks to mate.  Young males are inexperienced and don’t really know what to do or how to act and this can lead to some questionable activity…  In their hormonal eyes, a frozen penguin in the right position can look a lot like an interested female… Apparently necrophilia isn’t just restricted to penguins…  Lucy Cooke references pigeons mounting dead house martins, male house sparrows attempting to mate with dead females and the same going on with a couple of pheasants…

In addition to all of this wonderfully interesting and fun goings on, we have those animals which change sex.

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Birds do it, bees do it, even educated fleas do it…

Sex in the animal kingdom is vastly more exciting than much of human sex.  Just look at the praying mantis – she literally eats her mate!

The sex lives of animals are just as diverse as the different species are and, despite what some people might have you think, sex in the animal kingdom isn’t just for reproduction.  We can be sure of this because some animals have sex when they aren’t in season and so reproduction is not an option, and others engage in masturbation and same sex sexual activity.  That being said, in this post, I’m going to look at the sex itself and consider other sexual activity in another post.  To start with, let’s take a quick look at how you might attract a mate.

If you’re a male hippo, you might try spraying urine and faeces over the female that’s caught your eye.  A male bowerbird will build an elaborate bower to entice a female.  Other creatures might identify an appropriate male through song or scent or via chemical signals in urine markers.  For sea slugs, it’s a poke between the eyes that gets your partner in the mood…  Violence is also a hallmark for elephant seals, with the male being much bigger than the females.  A male will fight for a beach and then mate with all the females on it.  Whether they want to or not.  Some creatures will even use electricity to try and attract a suitable mate.

In different species, what makes an attractive mate differs.  For female zebra finches, it’s the level of exploratory behaviour that matters whereas for orangutans, it’s all about the males ability to share.  In the orangutan world, a male who shares is important because males can be coercive and sexually violent towards females.

If none of this convinces you of the complex nature of animal sex, perhaps you should check out the leopard slugs mating process, of which there is a handy youtube video.

Lets also take a quick look at pandas; pandas are well known for being terrible at sex but this isn’t the case.  A big issue with breeding in captivity has been trying to pair up same sex pandas and expecting baby pandas…

“The wild panda is a secret stud, fond of threesomes and rough sex… Female pandas prefer the males that can leave their sexy scent marks the highest up a tree.  Scientists have described males adopting a selection of athletic poses – ‘squat’, ‘leg-cock’ and, most remarkably, ‘handstand’ – in order to squirt their pee as high as possible.”
– Lucy Cook

We often assume in the animal kingdom that if monogamy is not the norm for a species, that it’s the male who has multiple partners whilst females have one.  This is not the case.  And biologically it makes sense.  If a female mates with a male and then realises there’s a better male, she’s going to want her babies to come from the second male so they are of the best genetic quality.  Additionally, there is a lot of sexual violence and coercion so the female may have been forced into mating with a male she doesn’t want to reproduce with.  For some males, a gift can entice the female and, in those species, it makes a lot of sense for the female to play the field!

“Female fallow deer deliver only a single offspring per year and therefore have limited chances to get it right.  They often seek the most dominant eligible bachelors for sperm deposits: however if too many females have ‘come-a-calling’ he’s liable to be sperm-depleted or may provide ejaculates with a more limited supply.  With only one offspring per year, it’s vital for females to ensure successful fertilisation, so they often engage in polyandry as a form of insurance.”
– Carin Bondar

When it comes to sex organs, the animal world is also pretty diverse.  Opossoms have bifurcated penises and vaginas which can accommodate these.  Hyena’s clitoris very closely resembles a penis and extends to an impressive 20cm!  The female spotted hyena is the only known mammal with no external vaginal opening, instead they have to urinate, copulate and give birth through the pseudo-penis… Painful!

Looking to the males of the world, we find a beetle with a spiny penis and ducks with corkscrew penises (and females with corkscrew vaginas of course).  Slugs also have corckscrew penises and if they happen to be reluctant to come out again after sex, the partner will just, er, nibble it off…  For the tuberous bush cricket, it’s the testes that cause the problem, taking up most of their abdomen:

“At nearly 14% of their body weight, they are disproportionately large when compared to other species. Just think, a 100kg human would be walking around with 14kg of testicles, which would be mighty uncomfortable.”
Susan Lawler

But if you thought that was mind blowing, wait till you hear about the Drosophila bifurca, or to you and me, a kind of fly.  The male produces 6cm sperm, more than 20 times the length of the male!

We tend to assume that orgasms are strictly a human affair but this isn’t the case at all.  scientists have detected orgasm in many different species including macaques, orangutans, gorillas and chimpanzees, although it should be noted these are generally the males of the species.  Perhaps because most human research about orgasms is about men and so the markers of an orgasm are male centric…  But that’s just this feminist’s ponderings about why…

There are also those animals that never have penis in vagina sex.  For example, African mouthbrooder cichlids reproduce orally.  Males will approach a female who then opens her mouth, which is where she carries her eggs, the male then sprays the eggs with sperm and fertilises them. Females will carry the eggs in her mouth until they hatch…

The argonaut octopus also doesn’t need to have ‘traditional’ sex.  Despite being very sexual, they engage in something called tele-sex where sperm is produced in a specially adapted penis which then detaches from the body and swims off to find a female. This penis then impregnants her and eventually the male regrows a new penis.

In another post I will consider animal sexuality but as a taster of what is to come, consider the whiptail lizards – a species made up entirely of females.  Instead of mating in the conventional way, or as a result of having both sets of organs, they make clones of themselves!  That said, they still need to engage in a mating ritual to stimulate egg production…  As only females are available, they take it in turns to act of the roles of males and females.

All of these weird and wonderful sounding sex lives just scratch the surface of how animals reproduce.  And as sex isn’t confined to reproduction, in another blog post, I’ll be looking more into the types of activity animals engage in without expecting babies to come along.

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