Archive for the ‘Gallery’ Category

Welcome to part 2 of the Arthropods special, and today I’m giving you a whistle-stop tour of the myriapods. This group includes centipedes and millipedes (as well as a couple of less important relatives), with approximately 12,000 species currently known.

Centipedes and millipedes are common enough if you look through leaf litter or under stones and flowerpots in the garden. What’s the difference between centipedes and millipedes? Well, a common mistake is about the number of legs (i.e. 100 for a centipede and 1000 for a millipede – this isn’t true). The number of legs in a centipede varies between 20 to 300, and in millipedes ranges from 36 to 750.

The easy way to distinguish between a centipede and a millipede is to look for the number of legs per body segment. A centipede has 2 legs per body segment and a millipede has 4 legs per body segment. They also differ in terms of diet – centipedes are active hunters and carnivores whilst millipedes are detritivores (eating decaying leaves).

Centipedes and millipedes are a very successful group, and have been around on the Earth for at least 440 million years. An earlier relative of centipedes and millipedes called Arthropleura lived 300 million years ago and was able to reach lengths of 2.5m. This makes it the largest land invertebrate ever, and could grow this large due to higher concentrations of atmospheric oxygen at the time.

So, here are some interesting photos of centipedes and millipedes from around the world. Enjoy!

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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!

 

A Celebration of the Moon

Posted: January 4, 2012 by Mr Bilton in Gallery, Physics, Space
Tags: , , , , ,

The US Space Agency NASA has succeeded in placing a set of twin satellites in orbit around the moon. The satellites, called the Grail Twins, are set to map gravity variations across the surface of our nearest neighbour.

This will allow scientists to understand the formation of the moon in more detail, and even to test recent suggestions that Earth may once have had two moons.

So, to celebrate this here are some pictures showing different aspects of a very familiar face.

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