This article is from
Creation 38(1):38–39, January 2016

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Charged-up spiders on the move

by Warren Nunn

It could be a scene from a Hollywood horror movie—millions of spiders descending from the sky on to a ship being tossed about on the ocean miles from land. While Hollywood would make them huge, man-eating spiders (and the crew would have to battle to survive the infestation), the real event isn’t scary. Instead, it is incredibly fascinating. It even happened to Charles Darwin on board HMS Beagle, about 100 km (60 miles) off the coast of Argentina in 1832. And it was Darwin’s observations of the spiders’ action that caused a modern-day scientist to consider the possibility that arachnids harness electrostatic energy to ‘balloon’ from point to point. Who hasn’t been ‘zapped’ by static electricity?

University of Hawaii physics professor Peter Gorham challenged existing aerodynamic theories to make the case for electrostatic flight in ballooning spiders by looking at the physics of such actions.¹

Gossamer threads

Some spiders (mainly hatchlings) have been observed producing silk threads (called gossamer) and ‘ballooning’ away on a kind of parachute for various distances, usually on the wind. They have also been recorded at great heights (up to 4,000 m [13,000 ft]) and are known to travel considerable distances.

After Mount St Helens erupted in 1980, millions of air-borne spiders descended on the area as it regenerated.² When the island of Surtsey was born of a huge undersea volcanic eruption off Iceland in 1963, the first people to set foot on it in early 1964 saw spiders ‘ballooning’ on silken threads.³ More recently, millions of spiders ‘ballooned’ into the rural city of Goulburn about 200 km (120 miles) south-west of Sydney, Australia.⁴ They can even ‘sail’ the seas.⁵

Gorham considered Charles Darwin’s notes of an extraordinary influx of ballooning spiders on to the Beagle, about which the world’s most revered evolutionist wrote:

“While watching some that were suspended by a single thread, I several times observed that the slightest breath of air bore them away out of sight, in a horizontal line. On another occasion (25^th) under similar circumstances, I repeatedly observed the same kind of small spider, either when placed, or having crawled, on some little eminence, elevate its abdomen, send forth a thread, and then sail away in a lateral course, but with a rapidity which was quite unaccountable.”⁶

The fact that Darwin saw spiders project away at such speed—and also horizontally—convinced Dr Gorham that electrostatic forces could be at work.

Flight control

To test this, Gorham considered the effect of the earth’s electrostatic field, the forces a spider would need to generate to ‘take off’, and why horizontal projection was sometimes observed.

Gorham concluded that a spider’s silk strand must produce a charge in order to ‘lift’. The silk has charge-bearing molecules (amino acids) which—when in contact with other materials—become negatively charged. Also, the silk is thought to charge as it leaves a spider’s spinneret (silk-spinning organ), which fits with observations of them launching vertically as well as horizontally.

To test why Darwin saw spiders launch horizontally from the Beagle, Gorham noted that on a computer-generated model of the vessel, it showed “a significant horizontal component [of the electric field] near the ships [sic] rail over most of its length”.¹

He concluded that “existing observations and the physics of spider silk in the presence of the Earth’s static atmospheric electric field indicate a potentially important role for electrostatic forces in the flight of Gossamer spiders”.¹

“Given these results, it appears that the near-horizontal launches observed by Darwin are consistent with expectations if the charge state of the silk is relatively high at the time of initial spinning or shortly afterward. Such launches are very difficult to explain by thermal convection given the calm conditions noted by Darwin,” Gorham wrote.¹

Gorham sees a naturalistic explanation to the phenomena that “will place the Gossamer spider’s electrification ability among the most striking evolutionary adaptations that Darwin encountered on his voyage”.¹

Extraordinary features

Spiders, of course, are perfectly designed by the Creator and endowed with this and other extraordinary features. Consider the following:

Spiders are yet another reminder of the Master Designer’s special creation which we know from the Bible occurred in six days, about 6,000 years ago. Now, who wouldn’t get a ‘charge’ out of that?