Two creatures front the rogues' gallery of spiders that haunt our dreams and skulk in the darkest recesses of our primerval fears. They each represent the divergent strategies that the order Araneida have adopted for capturing prey: active hunting and patient waiting. The citizens of a town in ancient Italy believed that a vigorous bout of dancing would whirl to death the venom of the tarantula. In truth, the large, hairy spiders that prowl on the ground or stalk from hidden holes appear formidable but are rarely fatal.
More lethal are members of the tribe that weaves webs and relies on fast-acting toxins to subdue dangerous prey such as bees and wasps. Perhaps the most dreaded spider of all is the black widow (Latrodectus mactans), whose bite is virtually painless. But after 10 minutes, the victim crumples under severe muscle cramps and the tactile agony of facies latrodectismi, with a sweat-drenched face, swollen eyelids, inflammed lips and morbid psychotropic visions. Death occurs if the venom, a potent neurotoxin, reaches the muscles of the thorax. For all its deserved reputation as a silent killer, the black widow is in reality less of a man-eater than many other spiders, more often than not neglecting to have her mate for dessert after sex.
Closer to home, the Australian red-back spider (Latrodectus hasselti) enjoys a similar claim to notoriety. Like her North American cousin, the red-back is bloated in black with a screaming streak of scarlet. Both ladies have a penchant for lurking in the overlooked corners of domesticity. Outhouses are known to be a common spot for scary encounters. But the dame from down under more rightly deserves the epithet bestowed upon her neotropical relation, as male red-backs perform a curious somersault during sex that places their abdomen right at the jaws of their mate, a sacrifice that persuades the female to prolong the pleasure of paired appetites.
The black widow and red-back are both placed in the family Theriididae, known innocuously as the comb-footed spiders. This family is distinguished by a 'comb' of serrated bristles on the final segment of the fourth pair of legs, which is used to guide the extruded stream of fresh threads during the wrapping of prey. At least 28 species of theriidids are known from Singapore, but fortunately Latrodectus is absent, at least til the day a crate of poorly inspected fruit arrives on our shores with a thousand-strong brood. Best known though of the family are the tiny Argyrodes spiders that live as kleptoparasites on the giant webs of Nephila. In scale, they appear like mites before their distant cousin who barely notices the activity of these red and silver freeloaders. Less conspicuous are the hump-backed comb-footers in the genus Chrysso, which have blade-like hairs on the tip of their abdomen. The specimen I found is known as the golden comb-footed spider, and little information seems available about its ecology other than its construction of a tangled three-dimensional web and glimpses of its family life, whereby some member of the genus practice maternal care of juveniles. Beyond this is a realm of unknown unknowns that defy investigation and shy away from the meddling minds of men who seek but a modicum of mental satisfaction before the webs come unwound under the shredding blades of mowers.
Here your photos are from Argyrodes. They are pretty common on Araneidae webs. And Nephilidae as well.
Jorge Almeida
Posted by: | 03 October 2007 at 01:25 AM