Masses of Christmas Island red crabs spawning on the beach


Arthropods are invertebrate animals that have an external, jointed skeleton usually known as a carapace. The phylum includes insects, crustaceans, centipedes, millipedes, spiders, scorpions and horseshoe crabs. The carapace has to be shed and regrown periodically as the animal grows larger.

Scientific name: Arthropoda

Rank: Phylum

Common names:

  • Arthropoda,
  • Arthropods

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Arthropod size range

Arthropods compared with a human from largest to smallest: Japanese spider crab, human, common lobster, bird-eating spider, Ama

A comparison of arthropod size in relation to humans - from the Japanese spider crab which is 4m across to the buff-tailed bumblebee, a mere 17mm long.

Fossil types

Learn more about the other animals and plants that also form these fossils.

Amber Amber
Amber owes its existence to the defence mechanisms of certain kinds of tree. When the bark is punctured or infected, a sticky resin oozes out to seal the damage and sterilise the area.


  1. Life
  2. Animals
  3. Arthropods

BBC News about Arthropods