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If I (accidentally) walk through a fresh spider’s web, is this a major blow to the survival chances of its occupant?
Jonathan Wallace
Newcastle upon Tyne, UK
spider’s web works by forming a barely visible, sticky net stretched across likely flight paths, such that flying insects accidentally crash into it, allowing the spider to eat them.
The properties that enable the web to catch insects mean there is also a substantial risk that other things may blunder into it too and, if they are large enough, destroy it. A large number of webs must be destroyed every day by mammals (including, but not limited to, humans), birds and even some larger insects.
The spider must expend energy to make its web and is prevented from feeding until the web is replaced, so there is certainly a cost to this. However, since orb-weaver spiders have been around for well over 100 million years and remain abundant and widespread, we may safely assume that, on average, the benefits of ambushing flies in a web significantly exceed the costs of that web getting trashed.
Of course, if the questioner were to systematically and immediately destroy the web each time the spider rebuilt it, that would be very harmful to the spider, but the occasional accident is very unlikely to constitute a major blow to its chances of survival.
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We may safely assume, on average, the benefits of ambushing flies in a spider’s web exceed the costs of webs getting trashed
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Pat French
Longdon upon Tern, Shropshire, UK
The first spider webs may have appeared more than 100 million years ago. At this time, some of the largest land animals ever to have lived on Earth were prolific and were blundering over the planet’s surface. It is inevitable that early spider webs were frequently destroyed. Yet they are still here and sauropods aren’t. The web catastrophe seems to have been survivable for the spider!
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