Spiders

more Insects...

The largest order of archnids comprising 40,000 species, spiders are found in every continent (except Antarctica). The incredibly diverse spiders are very ancient, with the first spider-like arachnids found a staggering 420 million years ago in Devonian era rocks while more modern spiders appeared 200 million years ago in the Triassic period.

 The vast majority of fossil spiders have been found preserved in amber (almost 1000 spider species), with the oldest dating from the Early Cretaceous, 130 million years ago. The advantage of amber is that it occasionally freezes spider behaviors, providing examples of mating, killing prey, parenting and even producing silk (even an amber fossil web over 100 million years old).

 Without antennae, they are uniquely set apart from insects: with the most centralized nervous systems of all arthropods, eight legs, and hollow chelicerae – mouth parts – used to inject venom into prey. All spiders are predators (with one exception), with some monsters preying on birds and lizards.

Their ubiquitous silk webs are used to trap unwary insects, and some species lasso targets with sticky silk bolas while avoiding detection camouflaged as their prey. Others run down their food, liquidizing it with digestive enzymes after grinding it down with their pedipalps.

 Their danger is not limited to their prey – males of most species might barely survive a few matings. Their social behavior ranges from toleration to co-operative hunting and food-sharing – a few species building webs live together in large colonies of up to 50,000 individuals.

 

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E-mail me Guy Iannuzzi at (guy@mentus.com)

 

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