Ballooning (spider)

Ballooning, sometimes called kiting, is a means by which spiders, and some other small invertebrates, can move through the air by releasing one or more gossamer threads to catch the wind. By this means they are wafted aloft and are at the mercy of the air currents. This procedure is mostly used by spiderlings to disperse, but larger individuals have been observed using it. The spider climbs to a high point, stands on its toes and points its abdomen to the sky, releasing fine silk threads from its spinnerettes until lift off occurs. Journeys achieved vary from a few metres to hundreds of kilometres. Even atmospheric data have collected samples of balloons at five kilometres above the earth and ships in mid-ocean have reported spider landings. Mortality is high.

Ballooning is a behaviour in which spiders and some other invertebrates use air-borne dispersal to move between locations. A spider (usually limited to individuals of a small species), or spiderling after hatching, will climb as high as it can, stand on raised legs with its abdomen pointed upwards ("tiptoeing"), and then release several silk threads from its spinnerets into the air. These automatically form a triangular shaped parachute which carries the spider away on updrafts of winds where even the slightest of breezes will disperse the arachnid. The Earth's static electric field may also provide lift in windless conditions.

Many spiders use especially fine silk, called "gossamer" to lift themselves off a surface, and silk also may be used by a windblown spider to anchor itself to stop its journey. The term "gossamer" is used metaphorically for any exceedingly fine thread or fabric. Biologists also apply the term "balloon silk" to the threads that mechanically lift and drag systems.

It is generally thought that most spiders heavier than 1 mg are unlikely to use ballooning. Because many individuals die during ballooning, it is less likely that adults will balloon compared to spiderlings. However, adult females of several social Stegodyphus species (S. dumicola and S. mimosarum) weighing more than 100 mg and with a body size of up to 14 millimetres (0.55 in) have been observed ballooning using rising thermals on hot days without wind. These spiders use tens to hundreds of silk strands, which form a triangular sheet with a length and width of about 1 metre (39 in)

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