When we think about killer sex, this is usually an adjective to describe amazing, mind-blowing sex. A virtual cornucopia of awesomeness. For animals, however, we could apply the term differently. That is to say, literally. Don’t misunderstand, animals have great sex too and there are whole hosts of species that have mastered the art of tantric sex. That is another blog post altogether. I am also not talking about sexual cannibalism. No, this is about animals that die, either from too much sex or because of some other feature that makes this inevitable.
Some might argue that if it is your time to go there is no better way to go than during sex. Honey bees might beg to differ. Honey bees have a complex social structure called eusociality. One of the key features of this type of social system is a division of labor within the group, or colony, as in the case of many social insects. This division of labor is a caste system where different bees assume different jobs. In honey bees you have the Queen, non-reproductive female workers, and male drones. Female workers have many jobs, including regulating the temperature of the hive, particularly where young bees are developing, gathering pollen for food, and laying unfertilized eggs that will become male drone bees.
Male drones are born to reproduce. Of the few lucky males that manage to reproduce with a new queen, you could say they explode with joy at the opportunity to have sex with her. Males have no stingers and spend their lives flying around, gathering in areas with other drones, vying for the attention of that one special Queen. The nuptials are undertaken in flight, which is a feat in itself. Although stamina is another topic, these little dudes copulate for 10-30 minutes. Turns out that how long a Queen mates with a drone is correlated with the amount of sperm he produces. Queens are assessing the males and shorten the act if necessary. The part that comes straight out of a science fiction novel is that when the male bees ejaculate their abdomen and sex organ (called endophallus) ruptures, or explodes, killing the male moments after he tumbles from the sky to the ground. However the tip of his endophallus remains in the Queen creating a kind of “plug”. This is probably the male’s ways of trying to guarantee that he is the only drone to mate with her. The irony is that, for him, suicide is often in vain as Queens will usually mate with as many as 17 males! Wouldn’t it be ironic if the Queen called out, “You were the bomb!”, as the male fell to the ground?
What, oh what, is a guy to do when all the females around him become sexually receptive at the same time? For one small carnivorous marsupial, the Northern Quoll (Dasyurus hallucatus), the answer is: try to have sex with as many of them as possible. But of course. Don’t worry ladies, the females do the same thing just without the consequences. These little fellas are obligate semelparous breeders. Semelparity means to breed once in a lifetime. This strategy has commonly evolved among bacteria, plants and invertebrates, and examples among vertebrates are rare. Females of this tiny endangered marsupial come into heat in the winter. There is no wonderful courtship, no long romantic dinners. Nope. These brutes grab the female by the neck and drag her off. Once she’s convinced that he’s the guy for her, he rocks her world for 3-24 hours at a time. Turns out these little boys don’t make much sperm so they have to do it a lot to guarantee being the baby daddy. The problem is that it takes so much energy to have sex for days at a time. Coupled with not taking the time to eat (wouldn’t want to miss an opportunity) this spells disaster for the males. Basically, they fall apart. They lose weight, become anemic, start losing their hair, and get infested with parasites. It is almost a blessing when they finally die! Apparently not just some of them die, but all of them die. One study reported ‘complete post-mating mortality within two-weeks’. The cause of death is stress associated with having to perform so much. Yikes! Everything in moderation fellas.
There must be something funny going on down under because there is another little Aussie species that rolls in the hay until it dies: The brush-tailed Australian marsupial mouse (Antechinus stuartii). So these males, like the Quoll, drop everything to have sex. They too are champion lovers when it comes to stamina, spending up to 12 hours with one female before they run off in search of another. Of course, a suppressed immune system, ulcers, and stress is too much for them, so they too die shortly after all goings on. Yet another marsupial species that follows the same pattern is the Red-tailed Wambenger (Phascogale calura). Now Wambenger is an appropriate name!
I remember as a kid being fascinated with Octopuses. And yes it is octopuses not octopi (Greek derivation, not Latin). They are expert chameleons, deftly using camouflage to hide from their predators. If they are seen, they either zip on out there at lightening speed, or combine tactics like speed with a well-placed ink squirt. They are pretty smart too and are considered the most intelligent invertebrate. They learn, have short-term and long-term memory, and a highly complex nervous system, which makes the fact that some countries allow surgical procedures without anesthesia barbaric. There have been several famous octopuses. Most recently, Paul the Octopus made headlines for successfully predicting the winners of the World Cup soccer matches. Sadly he died in October 2010, shortly after achieving fame. Because they are so clever, they are the quintessential escape artists (yet another topic!) and can get out of the most ‘secure’ tanks. With superior problem-solving skills, including unscrewing jars (see BBC article), many aquariums have faced the challenge of containing an octopus. A great book to read is The Octopus and the Orangutan by Eugene Linden. By now you might be thinking that octopuses are geniuses. However given all these smarts, some species apparently have a really hard time figuring out whose a boy and whose a girl! Octopus sex can be quite a drawn out affair going on for days at a time. Like the honey bee, the penis of the male octopus breaks off after mating. It is called a hectocotylus and is the third tentacle on a male. For many species, the male will re-grow his penis in time for the next season. For some though, the male will die within a few months of mating. In this case, however, the scales are a bit more balanced. Unfortunately, because females put so much effort into reproducing by producing so many eggs at once, the females also sometimes die shortly after releasing their eggs.
There are many other species (e.g., salmon, mole crickets, a few lizards, amphibians, butterflies, cicadas) that have a lot of sex and then keel over. As with anything there are trade-offs. It seems though that sometimes there can be too much of a good thing.
References:
Bradley, A.J., McDonald, I.R. & Lee, A.K. (1980). Stress and mortality in a small marsupial (Antechinus stuartii, Macleay). Gen. Comp. Endocrinol, 40:188–200.
Cheng, M.W. amd Caldwell, R.L. 2000. Sex identification in the blue-ringed octopus, Hapalochlaena lunulata. Animal Behaviour, 60:27-33.
Koeniger, N. and Koeniger, G. 2007. Mating flight duration of Apis mellifera queens: As short as possible, as long as necessary. Apidologie, 38: 606-611.
Oakwood, M. 2000. Reproduction and demography of the northern quoll, Dasyurus hallucatus, in the lowland savanna of northern Australia. Australian Journal of Zoology, 48:519-539.
Winston, M.L.1987. The Biology of the Honey Bee. Harvard University Press. Cambridge, MA.
