Ballooning, sometimes called kiting, is a process by which

spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

s, and some other small

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s, move through the air by releasing one or more gossamer threads to catch the wind, causing them to become airborne at the mercy of

air current In meteorology, air currents are concentrated areas of winds. They are mainly due to differences in atmospheric pressure or temperature. They are divided into horizontal and vertical currents; both are present at Mesoscale meteorology, mesoscale w ...

s and

electric field An electric field (sometimes called E-field) is a field (physics), physical field that surrounds electrically charged particles such as electrons. In classical electromagnetism, the electric field of a single charge (or group of charges) descri ...

s. A 2018 study concluded that electric fields provide enough force to lift spiders in the air, and possibly elicit ballooning behavior. This is primarily used by spiderlings to disperse; however, larger individuals have been observed doing so as well. The spider climbs to a high point and takes a stance with its abdomen to the sky, releasing fine silk threads from its

spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...

until it becomes aloft. Journeys achieved vary from a few metres to hundreds of kilometres. Even atmospheric samples collected from balloons at five kilometres altitude and ships mid-ocean have reported spider landings. Ballooning can be dangerous (due to predators, and due to the unpredictable nature of long-distance ballooning, which may bring individuals to an unfavorable environment). It is observed in many species of

s, such as '' Erigone atra'', '' Cyclosa turbinata'', as well as in spider mites ('' Tetranychidae'') and in 31 species of

lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

, distributed in 8 suborders. Bell and his colleagues put forward the hypothesis that ''ballooning'' first appeared in the Cretaceous. A 5-year-long research study in the 1920s–1930s revealed that 1 in every 17 invertebrates caught mid-air is a spider. Out of 28,739 specimens, 1,401 turned out to be spiders.

Description

Ballooning is a behavior in which spiders and some other invertebrates use airborne 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 upward ("tiptoeing"), and then release several silk threads from its

spinnerets A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...

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. Ballooning behavior may be triggered by favorable electric fields. Many spiders use especially fine

silk Silk is a natural fiber, natural protein fiber, some forms of which can be weaving, woven into textiles. The protein fiber of silk is composed mainly of fibroin and is most commonly produced by certain insect larvae to form cocoon (silk), c ...

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

metaphor A metaphor is a figure of speech that, for rhetorical effect, directly refers to one thing by mentioning another. It may provide, or obscure, clarity or identify hidden similarities between two different ideas. Metaphors are usually meant to cr ...

ically 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 have been observed ballooning using rising

thermal A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...

s 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 . Pardosa spp

In Australia, in 2012 and in May 2015, millions of spiders were reported to have ballooned into the air, making the ground where they landed seem snow-covered with their silk.

Distance and height achieved

Threads of silk following a mass spider ballooning

Most ballooning journeys end after just a few meters of travel, although depending on the spider's mass and posture, a spider might be taken up into a

jet stream Jet streams are fast flowing, narrow thermal wind, air currents in the Earth's Atmosphere of Earth, atmosphere. The main jet streams are located near the altitude of the tropopause and are westerly winds, flowing west to east around the gl ...

. The trajectory further depends on the

convection Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...

s and the drag of the silk and parachute to float and travel high up into the

upper atmosphere Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes: * The mesosphere, which on Earth lies between th ...

. Many sailors have reported spiders being caught in their ship's sails over from land (Heimer 1988). They have even been detected in atmospheric data balloons collecting air samples at slightly less than above sea level. Evidently, ballooning is the most common way for spiders to invade isolated islands and mountaintops. Spiderlings are known to survive without food while travelling in air currents of jet streams for 25 days or longer. Some

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

s and some

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder ...

s also use silk to disperse through the air. A close association has been found between ballooning behaviors and the ability for a species of spiders to survive afloat on water. Water-repellent legs keep them alive on both fresh and salt water, enabling them to survive waves up to 0.5 meters in height. In wind many species raised their legs or abdomens to use as sails, propelling themselves across the water's surface. Many species of spiders also drop silk to anchor themselves in place while afloat. Said spiders did not show these behaviors on land, suggesting that they are adaptations to water.

History

Although this phenomenon has been known since the time of Aristotle, the first precise observations were published by the

arachnologist Arachnology is the scientific study of arachnids, which comprise spiders and related invertebrates such as scorpions, pseudoscorpions, harvestmen, ticks, and mites. Those who study spiders and other arachnids are arachnologists. More narrowly ...

John Blackwall John Blackwall (20 January 1790 – 11 May 1881) was an English naturalist with a particular interest in spiders. Life Blackwall was born in Manchester on 20 January 1790. He lived at Hendre House near Llanrwst in north Wales from 1833 until ...

in 1827. Several studies have since made it possible to analyze this behavior. One of the most important and extensive studies exploring ballooning was funded by U.S. Department of Agriculture and performed between 1926 and 1931 by a group of scientists. The findings were published in 1939 in a 155-page bulletin compiled by P. A. Glick.

Description

Distance and height achieved

History

See also

References

Further reading