Posts Tagged ‘spiders’

Arthropods are great. I love ’em!

What are arthropods, you might be thinking? Well, the term arthropod (from the Greek for ‘jointed foot’) describes organisms that have hard exoskeletons, segmented body and jointed limbs – animals such as insects and spiders.

Arthropods are a remarkably successful group,  tracing their history back to a common ancestor that lived aabout 500 million years ago. Thanks to their hard waterproof exoskeletons they did very well in the sea, and were in fact the first animals on land. They later diversified into at 5 main groups:

  • Myriapods – including centipedes and millipedes
  • Chelicerata – including spiders, scorpions, horseshoe crabs and mites
  • Trilobites – an extinct group of marine animals (looked a bit like woodlice, but weren’t related)
  • Crustaceans – including crabs, lobsters, shrimp, barnacles and woodlice
  • Insects– including ants, bees, beetles and butterflies

    The arthropod family tree

There are at least over 1 million known species, and they make up 80% of all living species (that means if you took 100 random species from anywhere on the Earth, approximately 80 of them would be arthropods). They are incredibly populous – a conservative estimate of the number of insects alone (currently alive) is 10,000,000,000,000,000,000 (that’s 10 quintillion). That’s quite a lot.

So, in celebration of these fascinating and diverse organisms, this is part 1 of 5, each focusing on a different arthropod group. First up is Chelicerata – enjoy!

 

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