What are spiders?

Spiders are arachnids not insects, but both spiders and insects belong to the largest group of animals on Earth, the arthropods - animals with hard external skeletons and jointed limbs.

Spider origins

Spiders were among the earliest animals to live on land. Despite this their fossil record is relatively poor. They probably evolved about 400 million years ago from thick-wasted arachnid ancestors that were not long emerged from life in water. The first definite spiders, thin-wasted arachnids with abdominal segmentation and silk producing spinnerets, are known from fossils like Attercopus fimbriungus. This spider lived 380 million years ago during the Devonian Period, more than 150 million years before the dinosaurs.
What are the differences between spiders and insects?

  • Spiders have two main body parts, eight walking legs, simple eyes and piercing jaws (fangs), abdominal silk spinning organs, anterior abdominal genital opening
  • Insects have three main body parts, six walking legs, compound eyes, antennae, chewing jaws (mandibles - often secondarily modified), posterior abdominal genital opening
  • Spiders can't fly
  • Many insects can fly


    A great Spider resource page - http://www.austmus.gov.au/spiders/

The photos and all material viewed in my web site are exclusive and may not be used on any other site or in any other form without prior consent.
All Material Copyright © 2007 ~ All Rights Reserved.