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Feb 14

The Spider’s Guide to Not Being Eaten During Sex

Imagine the scenario: you’ve just got a new girlfriend and you’re heading over to her place for the very first time. After some pleasant conversation and a romantic, candlelit dinner, you both head to the bedroom to get intimate. Then, just as things start to heat up, your new girlfriend pounces on you and starts eating you. It’s perhaps not a problem many of us face, but it’s a real issue for the many spiders of the world.

In most spider species, the males have drawn the short straw – they are almost always the smaller sex. This sexual dimorphism makes a good deal of sense, for a female spider needs to be large to produce a lot of eggs; the bigger a male becomes, however, the more energy he needs to expend in finding a female, so it is advantageous for him to stay small and nimble.

Male_and_female_A._appensa

Photo: Sanba38
Male and female Argiope appensa

But there is a downside to this size discrepancy: a male spider can quite easily become a perfect-sized meal for his partner after they have finished mating. So if you happen to be a male spider who doesn’t want his first date to be his last, here are four ways to avoid being eaten by your lover.

1. Dance for her

According to people in the know, showing off your dancing skills in a nightclub can be a great way of picking up women. What I know, however, is that dancing can also stop you being on the menu all the time.

800px-Hogna_lenta_18

Photo: Patrick Edwin Moran

A male wolf spider uses visual signals to declare his identity and intentions to a female, raising high on his legs and gesturing with his conspicuously-patterned pedipalps (those mini-legs by the side of the wolf spider’s face in the picture above, which are sometimes mistaken for fangs). If the female isn’t in the mood for visitors, she runs at the male, who retreats very quickly. But persistence is the key here; if he continues dancing, the female wolf spider will eventually give in, allowing him to inject a droplet of sperm into her genital pore. How romantic.

2. Give her a gift

Today is February 14, or Valentine’s Day, so chances are people across the world are expressing their love for one another and exchanging gifts. The male nursery web spider, too, likes to give his partner a present… but he doesn’t expect anything in return apart from kindness and goodwill. In fact, the nursery web spider only gives the female an offering (usually a freshly-caught fly, specially gift-wrapped in silk) to distract her attention while he mates with her. As she takes the fly from him and tucks into it, it is safe for the male to duck under her and deliver his sperm.

Pisaura_mirabilis

Photo: Tomas Tarvainis

3. Rip your own ‘penis’ off

This seems like a rather extreme way of escaping cannibalism, especially since it means you won’t be doing much mating again, but in some instances it becomes a necessity. Technically speaking, spiders don’t have penises. Rather, they ooze sperm onto a special ‘sperm web’ beforehand and then suck it up the pair of aforementioned pedipalps, as if loading a hypodermic syringe. The pedipalps can then be inserted into the corresponding female slots to transfer the sperm… but some males must actually chew off their own pedipalps in order to get away safely.

A miniscule spider named Tidarren sisyphoides even removes one of his pedipalps prior to mating using a loop of silk and a sharp tug – rather like removing a wobbly tooth with a length of string and a door. Each of Tidarren’s pedipalps are huge (combined, they account for 20% of his overall body weight) in order to match the dimensions of the female’s genital opening, but these giant organs can seriously hinder the male when he is running. By removing one of them, Tidarren can still transfer his sperm and, better still, he is now faster, more agile, and can locate females more easily. Even better, Tidarren sisyphoides is so minute (he’s only around 1% the size of his mate) that the female doesn’t even notice that he’s there at all.

4. Accept the inevitable

Alternatively, rather than coming up with elaborate ways of avoiding the female’s fangs, you could just accept your fate and be done with it. Astonishingly, there is one species of spider, the Australian redback, which actually competes to be eaten. The male inserts one of his loaded pedipalps into her genital opening and then he does something suicidal: he jumps right into the female’s huge jaws.

But maybe there is a method to this madness. Males who sacrifice themselves during mating in this way have two advantages over those males who do not. The first is that males who are being eaten occupy the female’s entire attention while his sperm is being delivered, ensuring that no more males will be able to mate with her until she has finished feeding. The second advantage is that females who have already eaten a male are much more likely to reject subsequent males and their mating attempts.

Latrodectus_hasseltii_close

Photo: Toby Hudson

For the suicidal males, there will be no other chances to breed, so surely those males who don’t jump into their partner’s mouth will be able to mate multiple times and, in the long term at least, produce more offspring? Surprisingly, they probably won’t. The odds of a male redback finding even one female during his lifetime is very slim. This means that males are much better off throwing everything they have – including their own lives – into one successful mating rather than trying to find multiple females and potentially fathering no offspring whatsoever.

And if none of the tactics above take your fancy, you could take a leaf out of the funnel-web spider’s book and waft a kind of knock out gas towards your partner to leave her limp and docile (yet still able to mate), or follow the crab spider’s example and actually tie her down with silk to stop her being so aggressive. Take note, however, that none of these methods should be used in the human world. I have it on good authority that women don’t appreciate gifts wrapped up in silk, being knocked out beforehand, or having their partner chewing their own genitals off.

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