A male black widow spider. (Image: K. Korlevic) 
 
 Male widow spiders often end up as a tasty meal for their partners after sex, but new research shows that some males are employing a rather unsettling strategy to prevent this from happening, and it’s a little bit twisted. 
 
 New research published in Biology Letters shows that a significant portion of male widow spiders copulate with immature females, who are still too young to capture and consume their mate. These females have functioning reproductive organs, but their genitals are still internal and protected by a tough shell. Undaunted, the males penetrate right through this exoskeleton to deposit sperm. The young females, apparently not worse for wear, produce the male’s offspring once they’ve matured. 
 
 
 
 Normally, mature female widow spiders engage in sexual cannibalism—an evolutionary strategy that improves a species’ reproductive fitness as a whole. But in this case, the male widow spiders, who are normally monogamous, have adopted a strategy that’s allowing them to have sexual liaisons with multiple partners. It’s a completely selfish act but also one that improves an individual male’s reproductive success. As the researchers from University of Toronto Scarborough point out, this tactic is changing the sexual preference of male widow spiders, and it has the potential to change the evolutionary trajectory of this normally cannibalistic species. 
 
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 To perform the dastardly deed on the immature female, the male uses its fangs to cut through the exoskeleton. He then very carefully deposits his seed in the female’s sperm receptacle, called spermatheca. As far as the researchers can tell, this isn’t causing any injury to the female. The male has to be precise about the timing, doing it just a few days before molting when the female’s genitalia and sperm storage organs are fully developed but not yet exposed. 
 
 Spider sex with minors isn’t a rare occurrence. When the researchers went out into the field to collect immature females, they found that one-third of them had been violated in this way. 
 
 This sexual tactic is clearly a “thing” among the species, but only time will tell if it will become more popular over time. Sexual cannibalism evolved for a reason, so this kind of sexual experimentation may be peaking. For now, it remains a fetish among a species already known for its extreme and violent sex acts. 
 
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 [Biology Letters] ||||| Black widows are notorious spiders identified by the colored, hourglass-shaped mark on their abdomens. Several species answer to the name, and they are found in temperate regions around the world. 
 
 Venom 
 
 This spider's bite is much feared because its venom is reported to be 15 times stronger than a rattlesnake's. In humans, bites produce muscle aches, nausea, and a paralysis of the diaphragm that can make breathing difficult; however, contrary to popular belief, most people who are bitten suffer no serious damage—let alone death. But bites can be fatal—usually to small children, the elderly, or the infirm. Fortunately, fatalities are fairly rare; the spiders are nonaggressive and bite only in self-defense, such as when someone accidentally sits on them. 
 
 The animals most at risk from the black widow's bite are insects—and male black widow spiders. Females sometimes kill and eat their counterparts after mating in a macabre behavior that gave the insect its name. Black widows are solitary year-round except during this violent mating ritual. 
 
 Webs and Feeding 
 
 These spiders spin large webs in which females suspend a cocoon with hundreds of eggs. Spiderlings disperse soon after they leave their eggs, but the web remains. Black widow spiders also use their webs to ensnare their prey, which consists of flies, mosquitoes, grasshoppers, beetles, and caterpillars. Black widows are comb-footed spiders, which means they have bristles on their hind legs that they use to cover their prey with silk once it has been trapped. 
 
 To feed, black widows puncture their insect prey with their fangs and administer digestive enzymes to the corpses. By using these enzymes, and their gnashing fangs, the spiders liquefy their prey's bodies and suck up the resulting fluid. ||||| The males of several species of insect-eating marsupials have a very unusual life history. They mature quickly, often in less than a year. Then, during a short and frenzied breeding season, they mate repeatedly — for up to 14 hours in some cases — until their immune systems crash and their bodies start to fall apart. Then they die. (Talk about going out with a bang.) 
 
 This strategy, called suicidal reproduction, or semelparity, is seen in some animals and plants, but is quite rare in mammals, said Diana Fisher, a researcher at the University of Queensland, Australia. The behavior is only found in these marsupials, a group of mammals in which young can be carried in a pouch. 
 
 Most animals that pursue this tactic, like squid and spiders, have many offspring, making it more understandable from an evolutionary point of view: Though they die after mating, they likely have thousands offspring to which they pass on their genes, Fisher told LiveScience. But marsupials, like most mammals, only have a few offspring at a time. [Top 10 Swingers of the Animal Kingdom] 
 
 Not altruistic 
 
 When the behavior was first noted in the mid-20th century amongst marsupials in Australia and several Pacific Islands like New Guinea, scientists were perplexed. At first, some thought the behavior could be a type of altruism; by dying, the males left more insects to be eaten by their offspring, Fisher said. 
 
 But recent research, culminating in a paper published today (Oct. 7) in the journal Proceedings of the National Academy of Sciences, shows that males live fast and die young for another reason: to fertilize females with the highest quality sperm, in order to pass on their genes to as many offspring as possible. 
 
 In the study, Fisher and colleagues compared suicidally reproducing (or semelparous) marsupials with other marsupials that mate on multiple occasions throughout life (iteroparous). The researchers found that the semelparous animals have much larger testes relative to body size, which are better for storing sperm, Fisher said. In fact, these semelparous males actually stop producing sperm before mating begins, so they can put all of their energy into marathon mating sessions. For instance, male Antechinus, a group of mouselike marsupials, can mate for 14 hours and even break down their muscles to give them more energy, Fisher said. 
 
 "They must rely on stored sperm throughout the mating season, and the clock is ticking, because the limited store of sperm is continually lost in their urine," Fisher said. "The have a frenzied mating season lasting only a couple of weeks, and males usually die before young are born." 
 
 Live fast, die young 
 
 Scientists also found that semelparous species have shorter breeding seasons, so males have a short time to "sow their wild oats," so to speak. 
 
 All of this leaves males exhausted, and they usually die of infections or internal bleeding — they "mate themselves to death," Fisher said. The mating is timed so that offspring are born just before the largest number of insects emerges, in the summertime, she added. 
 
 Instead of duking it out like males of some species, like bighorn sheep, for access to females, the males compete with their sperm. Females usually mate with multiple males and may sire offspring from multiple fathers. But the best sperm wins — and to maximize the quality, the males sacrifice everything, Fisher said. Previous work has shown that promiscuous female Antechinus, which mate with multiple males, have more offspring than those with a single partner. 
 
 "This is a form of post-mating sexual selection in which males compete with their sperm inside the female reproductive tract, rather than fighting to gain access to females," Fisher said. "It is associated with having large testes with lots of sperm-producing tissue, and often also long mating times and mate-guarding, and of course promiscuity." 
 
 The sperm-competition idea also explains why males mate for so long — to prevent, or at least minimize, the amount of time other males can mate with their partner, Fisher added. 
 
 Email Douglas Main or follow him on Twitter or Google+. Follow us @livescience, Facebook or Google+. Article originally on LiveScience.
– No one—but no one—likes to get killed for having sex, and as that is often the fate of male black widow spiders, the critters are evolving a mating tactic that is, anthropomorphically speaking, more than a little creepy. Researchers found a startling, and slightly unsettling, mating shift in a study titled "Copulation with immature females increases male fitness in cannibalistic widow spiders," published in Biology Letters and translated into English as "Dirty old men spiders avoid violent death, increase number of babymamas by chasing jailbait female spiders." Essentially, Gizmodo notes, the males of the species have noticed that they keep getting killed when mating with sexually mature females. But if they chase young spider-skirt, the immature females aren't capable of killing them. Here's how it works: The young females' reproductive organs are functional, but internal, and protected by an exoskeleton. The dirty old man spiders cut through the exoskeleton with their fangs, and leave a special sperm delivery in the female's sperm receptacle. It's a narrow window in her development, but when the female matures, she pops out the male's spider babies. Writes Gizmodo: "Spider sex with minors isn’t a rare occurrence. When the researchers went out into the field to collect immature females, they found that one-third of them had been violated in this way." It's an evolutionary win-win for the male, who is a) still alive, and b) free to go out and mate again, thereby increasing his progeny. (Here's a graphic description of what it's like to get bitten by a black widow. Hint: Not fun.)