Spider Silk – Leslie Brunetta & Catherine L. Craig *****
Somewhere in Spider Silk the authors describe one of the first arachnids coming out of the sea onto the land around 400 million years ago. There was little vegetation but for 150 million years these trigonotarbids persisted. They had eight legs and they looked very much like today’s spiders, but with one very important difference: they made no silk.
Silk-making arachnids, attercops, arrived, perhaps, around 20 million years later, but it was not until 290 million years ago that the first arachnids with spinnerets arrived on the scene. These were called mesotheles and 90 species survive to this day. Their mating ritual involves limbo dancing. Some of them lay trip wires. They live in burrows lined with silk and with silken trap doors, and from these they lie in wait…
The mygalomorphae, which arrived 50 millions years later, are hairy and rather large (the tarantula is an example) and unlike the mesotheles, have spinnerets at the end of their abdomen which gives them greater flexibility in web design. Some of them are lethally amorous: interrupt the hour-long clinch of the Sydney Funnelweb at your peril. A bite from one of these little beauties can cause an autonomic storm that can be fatal in the vulnerable.
The next development came with the araneomorphs. These are the most successful arachnids in the world today. They outnumber the mesotheles and mygalomorphs by fourteen to one, and are the silk connoisseurs. All arachnids produce different sorts of silk, but the silk of araneomorphs is made to order. It can be superstrong, superstretchy, supersticky or superfluffy according to requirements – and scientists would love to emulate it.
136 million years ago the araneoidea superfamily came up with the spider trade-mark: the orb. However, since this turned out to have a major design flaw, this is under further development by firm arachnid today.
The book makes fascinating reading with plenty of quirky spider facts. The origin, genetics and molecular structure of the silk is assessed and used to explain the properties, and all of this then set in the context of the web and the behaviour of the spider. Along the way it takes the opportunity to discuss aspects of basic genetics, developmental evolutionary theory and evolution itself. In fact, its description of the finer points of Darwin’s evolutionary theory and the explanation of how it differed from earlier theory was the best I’ve ever read. It will give you a new appreciation of the wild life of your home, and give you an excellent excuse not to dust.