General Arthropod Characteristics

  • Coelomate, Triploblastic
  • Protostome (Ecdysoan)
  • Cephalization
  • Open Circulatory System
  • Tagmatization
  • Exoskeleton made of Chitin
  • Jointed Appendages
  • Molting (ecdysis)
  • Live in almost all habitats on earth
  • Estimates of 30-100 million species! (Mostly Insects)


Subphylum Trilobitomorpha (extinct)

Subphylum Chelicerata- arachnids, horshoe crabs

Subphylum Mandibulata

  • Class Crustacea
  • Class Insecta (in superclass Hexapoda)
  • Class Myriapoda – millipedes, centipedes


Three Major Functions of the Exoskeleton

  1. Protection from predators
  2. Prevention from dessication
  3. Locomotion (attachment sites for muscles)

Sclerotization- Hardening of the procuticle after molting (also called tanning)

Sclerites- Different segments or body parts covered by exoskeletal plates

Joints are places that are thin and flexible

Diversity of Appendages legs, wings, antennae, mouthparts…

Ecdysis- The process of molting

  • Controlled by the hormone ecdysone

Complete Digestive Tract

Arthropods have striated muscle