Sunday, September 5, 1999
WITH many species of spider, the female is threateningly large in comparison with the male, and may easily mistake him for a trapped insect and proceed to eat him. So any male wanting to mate must approach with utmost caution. Different species of spider use different tactics. A male may frantically wave his legs or his pedipalps (the sensory appendages on his head), or he may tread carefully over the females web using a complicated dance-like step to distinguish himself from any other insect. Alternately, he may resort to bribery and offer her an insect as a distracting snack.
In the case of Pisaura mirabilis, during breeding season these spiders scurry about in fresh green vegetation in search of a female. As soon as they come across her tracks or the signal thread that the female drags behind her, they set off with new energy to hunt for flies. When the male catches a fly, it immediately starts entwining it in its cobweb until a white ball is formed.
He carefully holds the wrapped fly in his mouth and ceremoniously carries it in its silken packet to the female. When he sees her, he freezes in a bizarre, grotesque position, and then, very courteously, presents his gift. He stands in front of the female spider like an enigmatic and incomprehensible sculpture at an art exhibition. The male rests on the bottom of his vertically extended abdomen and on his six legs. His fourth pair of legs are raised over the fly packet that he is holding in his mouth.
The female spider, who must be stunned by this unusual sight, slowly moves towards him as if she cannot believe her eyes. She then accepts the wedding gift, tears up the packet and starts sucking on the fly. Should the male turn up without a gift, he is in for it. The female will eat him up. But spiders can also cheat. Some bridegrooms pack up the remains of a fly carcass for their date. Some males are even more clever. They carefully wrap up nothing at all and give their female a large but completely empty cocoon to unwrap. The wrapping is important because it takes a female a long time to unravel it and get at her prize, and while she is preoccupied the male has long enough to mate without being eaten. With tactics like these, speedy sex becomes the order of the day.
Male spiders employ even more varied techniques to avoid being their own wedding breakfast. Some males overcome this problem by making a series of special visual signals from a respectful distance. Others tap out a code of distinctive vibrations on the females web, tweaking the threads in a rhythm that lets her know that they are males and not meals. Some males are more assertive and put the female into a kind of hypnotic sleep by biting her in a special way, or by tying her down with silken threads and then mating with her when she is well wrapped up. Many of these tactics work and the males live to mate another day, but from time to time they fail and the female satisfies her protein hunger by sucking her mate dry an undeniably efficient way of giving her newly fertilised eggs a nutritious start in life.
Tarantulas or bird-eating spiders do not have good eyesight, so they communicate by touch. When a tarantula male meets a female, he signals his presence by using his front legs to drum a tattoo on her body. She is alarmed, and raises her front legs ready to strike. It takes a lit of soothing and stroking from the male to calm her down.
At last she raises her body and opens the lethal fangs that could finish him off with a single bite. But he is not unprepared. He has hooks on his front legs specially for holding her jaws apart. Safe at last, the male inseminates the female and then makes his retreat as quickly as possible.
In the above mentioned
cases it is one kind of cannibalistic tendency where
adults eat adults, but there are cases where adults are
eaten up by their offsprings. Once the life-giving and
protective roles of the adults have been completed, they
are still good for a meal. The female wall spider often
dies before her young are ready to leave their cocoon
nest. If this happens, they devour her body when they
finally emerge. In this way they are provided with an
easily obtained first breakfast before they set off to
explore the world. A similar occurrence has been observed
in certain sheet-web spiders too.
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