Most here will be familiar with the basics of mating amongst sexually differentiated organisms. Leaving aside for a moment yeasts, which have a peculiar sexual differentiation that is considered to be an earlier, antecedent form prior to the emergence of male and female, and concentrating upon those organisms that possess a recognisable male and female sex, most mating transactions between these organisms follow a basic pattern, in which males seek to transfer their sperm to females via some means. Probably the simplest system is seen in mosses, in which the male organisms simply release their sperm into the moisture covering their surfaces, and the sperm swim through that moisture to an adjacent female moss. However, once we move into the world of metazoans, life starts to become more complicated.

For one thing, female investment in reproduction is usually greater than that of the male. Consequently, it pays for a female to be discriminating with respect to mating partners, and reserve her unfertilised eggs for the choicest suitor. Males, on the other hand, have a vested interest in finding ways around that. Whilst tracking down some literature on insect phylogeny, I alighted upon some truly bizarre variations on the mating theme, which I think everyone will appreciate me sharing here, and which, whilst being bizarre to our way of thinking, are still eminently within the remit of evolutionary theory to explain, and indeed, only make sense within an evolutionary paradigm.

The first example I'll give is the spider species Harpactea sadistica, whose taxonomic name derives directly from its interesting mating habits. Males of this species bypass the usual mating process, and, upon having subdued a female, instead of using the pedipalps to deposit sperm in the female's spermatheca (the usual procedure in spiders), chooses a more direct mating route. Using modifications of the pedipalps resembling hypodermic needles, he injects his sperm through the female's body cavity, aiming precisely for her ovaries. It should not require much imagining why the specific name sadistica was chosen for this unique spider.

However, there are other examples of what might be termed 'hypodermic insemination'. Many of the unusual species belonging to the Order Strepsiptera, a group of parasitic insects that are themselves a taxonomic headache of 200 years duration, courtesy of their quixotic morphology, again bypass the usual business of joining genitaila in order to mate. In this case, because the females have no genitalia to speak of. The usual collection of chitinous parts seen in other female insects is either vestigial or absent, and the male mates with the female by inserting his hypodermic copulatory organ behind the female's head. Here is located a brood canal, which the male has to rupture in order to gain access. Even more weirdly, the female Strepsipteran hatches the eggs inside her own body cavity, and the first instar larvae swim around in her haemolymph until it is time to emerge into the outside world, which they do through the same brood cavity that the male subjected to attack earlier. Indeed, female Strepsipterans have largely given up on possessing virtually all of the usual adult insect features, lacking eyes, limbs, genitalia and being little more than a sort of bag with a mouth at one end. The males, possessing a full set of eyes, limbs and wings, have to move pretty sharply in order to copulate with these seemingly unprepossessing partners, because an adult male Strepsipteran has no mouthparts, and his energy reserves run out after about five hours, whereupon he comes crashing to a halt and dies.

Slightly less weird from the point of view of morphology, but again, weird from the standpoint of dispensing with the usual sexual etiquette, is the familiar Bed Bug. Males once more simply stick their copulatory organs through the female's body wall. However, just to add a little spice to the proceedings, the species has evolved an interesting development in the female - a set of paragenital organs that act as a sort of 'bulls eye' marker for the male. Quite a few Hemiptera have developed this arrangement, but the Bed Bug is the species that is best studied.

One Hempiteran species that is gaining increasing attention from scientists, is a flower bug called Xylochloris maculipennis. Like the familiar Bed Bug, this species discards the usual sexual etiquette, and the male simply drives his penis through the female's body wall. But in another bizarre twist, males of this species will also perform the same act upon other males. It is hypothesised that this instance of homosexual hypodermic insemination is a means of decommissioning the genitalia of rival males, though research has yet to answer conclusively this and several other questions about the wacky sex life of this bug species. However, the injected sperm appear to head straight for the testes of the recipient, where they are digested, giving the recipient a protein and energy boost at the expense of the male that performed the injection. It is therefore possible that some males may give off female signals to a rival male, in order to waste that male's sexual investment, and remove him from competition.

However, perhaps the oddest of all these organisms is a Rotiferan, known as Asplanchna brightwelli. In order to inseminate the female of the species, the male dissolves a hole in her side.

And as if all of this were not strange enough, it's possible that some species use this abandonment of sexual etiquette as an ecological weapon. Hesperocimex sonorensis and Hesperocimex cochimiensis are two bug species that share an ecosystem (they are blood sucking parasites upon the same bird species), and which both practice hypodermic insemination. However, it's possible that the latter species uses sex as a weapon to displace the former. If a male H. cochimiensis inseminates a female H. sonorensis, the result is a massive, rapid and lethal immune reaction. Which means that cochimiensis may use cross-species sex in order to remove food rivals from the scene, by using shagging as a biological weapon.

Just when you thought biology couldn't come up with anything more that boggled the mind, along comes yet another collection of organisms that make you think "WTF?". In this, case, literally.

Nekked pics?! ;)

But seriously, would make for an excellent documentary.

All obviously designed. By a completely sadistic, sick, twisted, immoral God. So the bible is true, see?

So what's the intermediate? Males with bad aim?

Animavore wrote:So what's the intermediate? Males with bad aim?

It is probable that the ancestral state used the ... ummm ... normal channels. They lead sperm where they need to go. But if the male organ developed into something a little less gentle, piercing the canal, the possibility opens up to dispense with convention altogether. Particularly if the female canal is blocked by a previous suitor, selecting for the bypass method - and among them, for those with better aim. The female organ then becomes somewhat redundant, as do conventional suitors.

Is it safe to assume that the females in question do not suffer badly from having their bodies pierced. Do we know how the females cope with these assaults, do they have enhanced recuperative powers, for example?

Barnacles - Darwin is still the textbook on them. In one the male lives inside the female and is reduced to basically being a sperm sac, all other life support provided by the female - a logical removal of duplication!

And I think another barnacle has the largest penis in comparison to body size.

Calilasseia wrote: If a male H. cochimiensis inseminates a female H. sonorensis, the result is a massive, rapid and lethal immune reaction. Which means that cochimiensis may use cross-species sex in order to remove food rivals from the scene, by using shagging as a biological weapon.

Invertebrate immune system. I don't know much about that. They only possess an innate immune system, I suppose?

I like the parts about using sex as a weapon. Very interesting, especially the enticing homosexual behaviour in order to gain protein reserves. Fact is stranger than fiction.

Clive Durdle wrote:Barnacles - Darwin is still the textbook on them. In one the male lives inside the female and is reduced to basically being a sperm sac, all other life support provided by the female - a logical removal of duplication!

See also Bonellia viridis and some angler-fish.

it's a weird, weird world. thanks cali. rivetting stuff as always.

I thought this thread is about sex positions.

Clive Durdle wrote:And I think another barnacle has the largest penis in comparison to body size.

Acorn barnacle, I believe.

UPDATE:

Here's the paper on Harpactea sadistica ...

The Spider Harpactea sadistica : Co-Evolution Of Traumatic Insemination And Complex Female Genital Morphology In Spiders by Milan Řezáč, Proceedings of the Royal Society of London Part B, 276: 2679-2701 (7th August 2009) [Full paper downloadable from here

Řezáč, 2009 wrote:The males of invertebrates from a few phyla, including arthropods, have been reported to practise traumatic insemination (TI; i.e. injecting sperm by using the copulatory organ to penetrate the female’s body wall). As all previously reported arthropod examples have been insects, there is considerable interest in whether TI might have evolved independently in other arthropods. The research reported here demonstrates the first case of TI in the arthropod subphylum Chelicerata, in particular how the genital morphology and mating behaviour of Harpactea sadistica (Řezáč 2008), a spider from Israel, has become adapted specifically for reproduction based on TI. Males have needle-like intromittent organs and females have atrophied spermathecae. In other spiders, eggs are fertilized simultaneously with oviposition, but the eggs of H. sadistica are fertilized in the ovaries (internal fertilization) and develop as embryos before being laid. Sperm-storage organs of phylogenetically basal groups to H. sadistica provide males with last male sperm priority and allow removal of sperm by males that mate later, suggesting that TI might have evolved as an adaptive strategy to circumvent an unfavourable structure of the sperm-storage organs, allowing the first male to mate with paternity advantage. Understanding the functional significance of TI gives us insight into factors underlying the evolution of the genital and sperm-storage morphology in spiders.

And as if that wasn't enough, how about detachable spider penises?

This article provides you with the layman's introduction to this phenomenon. For those more interested in the paper, here it is:

Genital Damage In The Orb-Web Spider Argiope bruennichi (Araneae: Araneidae) Increases Paternity Success by Stefan H. Nessler, Gabriele Uhl and Jutta M. Schneider, Behavioural Ecology, 18: 174-181 (2007) [Full paper downloadable from here]

Nessler et al, 2007 wrote:The morphology of male genitalia often suggests functions besides sperm transfer that may have evolved under natural or sexual selection. In several species of sexually cannibalistic spiders, males damage their paired genitalia during mating, limiting them to one copulation per pedipalp. Using a triple-mating experiment, we tested if genital damage in the orb-web spider Argiope bruennichi increases male fitness either through facilitating his escape from an aggressive female or by obstructing the female’s insemination ducts against future copulation attempts from other males. We found no survival advantage for males damaging their pedipalps; however, copulations into a previously used insemination duct were significantly shorter when the previous male had left parts of his genitalia inside the insemination duct. Because copulation duration determines paternity in this species, our result suggests that male genital damage in A. bruennichi is sexually selected. By breaking off parts of their intromittent organs inside a virgin female, males can reduce sperm competition and thereby increase their paternity success.

So, apparently in this species, males who have their dicks broken are more successful parents. Who in their right fucking mind would "design" THIS?

Meanwhile, more on detachable spider penises! First, try this Scientific American article, which provides the non-technical introduction to this. Then, we can move on to the paper, namely:

Intersexual Arms Race? Genital Coevolution In Nephilid Spiders (Araneae, Nephilidae) by Matjaž Kuntner, Jonathan A. Coddington & Jutta M. Schneider, Evolution, 63(6): 1451-1463 (June 2009) [Full paper downloadable from here]

Kuntner et al, 2009 wrote:Genital morphology is informative phylogenetically and strongly selected sexually. We use a recent species-level phylogeny of nephilid spiders to synthesize phylogenetic patterns in nephilid genital evolution that document generalized conflict between male and female interests. Specifically,we test the intersexual coevolution hypothesis by defining gender-specific indices of genital complexity that summarize all relevant and phylogenetically informative traits. We then use independent contrasts to show that male and female genital complexity indices correlate significantly and positively across the phylogeny rather than among sympatric sister species, as predicted by reproductive character displacement. In effect, as females respond to selection for fecundity-driven fitness via giantism and polyandry (perhaps responding to male-biased effective sex ratios), male mechanisms evolve to monopolize females (male monogamy) via opportunistic mating, pre- and postcopulatory mate guarding, and/or plugging of female genitalia to exclude subsequent suitors. In males morphological symptoms of these phenomena range from self-mutilated genitalia to total castration. Although the results are compatible with both recently favored sexual selection hypotheses, sexually antagonistic coevolution, and cryptic female choice, the evidence of strong intersexual conflict and genitalic damage in both sexes is more easily explained as sexually antagonistic coevolution due to an evolutionary arms race.

thqnks cqli, very interesting