Chapter 1.5: Phylum Arthropods

• Class of Arthropods


  1. Insects

  2. Crustaceans

  3. Arachnids

  4. Myriapods
• Special Features of Arthropods

  -no backbone (invertebrates)

  -waterproof hard exoskeleton --> exist in dry places, unlike other invertebrates

  -segmented bodies

  -jointed limbs (exoskeleton prevents movement)
• Insects


  Successful group due to their exoskeleton and tracheae that stop water from evaporating from their body -->. they can live in very dry places!

  
  

  - 3 pairs of jointed legs

  - 1 or 2 pairs of wings

  - 1 pair of antennae

  - 3 body parts: head, thorax, abdomen

  - 1 pair of compound eyes

  - Breathe thru trachae
• Crustaceans


  Lobster, woodlice, crab; most live in wet places, many are aquatic

  
  

  - > 4 pairs of legs

  - 2 pairs of antennae

  - 2 body parts: cephalothorax, abdomen

  - Exoskeleton is often calcified to form an exceptionally hard carapace (upper shell) for protection

  - compound eyes

  - breath thru gills
• Arachnids


  spiders, ticks, scorpions; live on land (land- dwelling)

  
  

  - 4 pairs of legs

  - no wings

  - 2 body parts: cephalothorax, abdomen

  - several pairs of simple eyes

  - all have piercing jaws since all are predators

  - have chelicerae (pointed mouthparts) for biting and poisoning prey
• Myriapods


  centipedes, millipedes

  
  

  - long, thin body; many sgments to move easily thru soil + leaf litter

  - no obvious thorax and abdomen

  - each segment has jointed legs (> 9 pairs)

  - 1 pair of antennae as sense organs in dark habitats

  - simple eyes