The Private Life of Spiders

Book Review

The Private Life of Spiders by Paul Hillyard

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The Private Life of Spiders explores a fascinating world of competition and a fight for survival.  Join arachnid expert Paul Hillyard on a tour of some of the most remarkable and diverse spiders, from the solitary bird-eating tarantula to the African Sheet Web Spider, which can live in colonies of over one thousand individuals.

Featuring species from all around the world and in a range of different habitats.

Illustrated with over 100 superb colour photographs highlighting the beauty and diversity of spiders.

With information on spider anatomy, behaviour, reproduction and social organisation, as well as on web construction and hunting techniques.

Hardcover 160pp

Contents: Background to Spiders; Spiders that Hunt; Spiders that Build Webs; Tarantulas and Trapdoor Spiders; The Silk Factory; Mating and Breeding; The Use of Venom; Social Spiders; Spiders and Humans; Glossary; Further Reading; Index.

Excerpt
Page 19
Ballooning and the Phenomenon of Gossamer
Spiders populate remote places by a method of airborne migration known as ballooning.  With the aid of long strands of silk drawn out by the breeze, small and young spiders, under 1cm in length, become airborne and may drift considerable distances depending on the weather conditions.  They have been collected on ships, hundreds of kilometres from the nearest land, as well as in samples of aerial plankton at altitudes up to 5,000m.  Charles Darwin, writing in the Voyage of the Beagle, recorded that on 1 November 1832, at a distance of 100km from the coast of South America, the ship’s rigging became covered with vast numbers of dusky red spiders about 2mm in length.  It happened again 25 days later, demonstrating that such a fall of spiders at sea is not a rare event.

At the right time and place, it is quite possible to observe what actually happens during take-off.  The spider climbs to the top of a fence post, or other prominent point.  It turns to the wind and stands on extended legs with the spinnerets uppermost.  A thread is initiated and drawn out further by the breeze.  When the pull on the line is sufficient, the spider turns, grabs the thread, releases its hold on the post, and away it goes.

Do spiders have any control over their flight?  Theoretically, they do.  They can descend more rapidly by rolling the thread into a ball and tucking their legs in.  Also, they can fly further by building extra silk (sails) into the thread.  Probably, however, they have little or no control over the direction of flight.  If it happens that they land in an unsuitable place, might they decide to take off again?  Yes, this certainly happens on ships at sea; Darwin observed it on the Beagle.  In fact it has been firmly established that spiders will move on if they find themselves a poor site.

Gossamer, the extremely light material made of silk threads, is associated with ballooning.  On days when there is much ballooning activity, either taking-off or landing, there can be more than a million spiders to the acre, each one trailing a line.  Lines may accumulate to form a silvery sheet over the land which, on a sunny dewy morning, makes a beautiful sight.  But, as the morning progresses, rising air currents break up the sheet and lift the resulting pieces of gossamer, like bits of rage, into the air.
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Species that are able to disperse by ballooning tend to have a wide distribution in the world, while those that cannot balloon are limited to walking.  At one end of the scale are cosmopolitan species with the ability to disperse and tolerate a wide range of habitats, while at the other end are specie confined to specific niches in limited geographical ranges.  For example; The Great Barrier Reef islands have been colonised by a variety of spiders (of many different families), but not by the large tarantulas which are common on the mainland, a short distance away.  They young tarantulas are usually too heavy to balloon and neither can they swim.  Today, many species have spread around the world thanks to international trade.  One such is the so-called banana spider (Heteropoda venatoria).  Transported together with bananas, it has now spread throughout the tropics and sub-tropics as far north as Florida and Israel.  Europe, however, remains too for it to survive permanently.