Phylum Athrapoda

• Classes of Arthropods


  • Insects
  • Crustaceans
  • Arachnids
  • Myriapods
• Arthropods


  • Jointed limbs
  • Hard, firm, external skeleton called a cuticle
  • Segmented bodies with flexible joints between segments
  • Distinct head, thorax, and abdomen regions
• Insects


  • Segmented bodies with a firm exoskeleton
  • Three pairs of jointed legs
  • Compound eyes
  • Two pairs of wings
  • Distinct head, thorax, and abdomen regions
  • Only one pair of antennae and three pairs of legs (different from crustaceans)

  
• Insects have successfully colonized the land due to their cuticle preventing water loss and allowing survival in dry climates
• Crustaceans


  • Exoskeleton
  • Jointed limbs
  • Two pairs of antennae
  • Compound eyes
• Most crustaceans live in wet places and are aquatic, as they breathe through gills
• Arachnids


  • Spiders
  • Scorpions
  • Mites
  • Ticks

  
• Arachnids


  • Body divided into cephalothorax and abdomen
  • Four pairs of limbs on cephalothorax
  • Two pairs of pedipalps (one for reproduction, one for piercing and paralyzing prey)
  • Several pairs of simple eyes

  
• Myriapods


  • Millipedes
  • Centipedes

  
• Myriapods


  • Head and segmented body not clearly divided into thorax and abdomen
  • Pair of legs on each body segment (millipedes have two pairs per segment)
  • One pair of antennae
  • Simple eyes
  • Centipedes are carnivores, millipedes are herbivores