Phylum: Arthropoda


  • Coelomate, Triploblastic
  • Prorostome (Ecdysoan)
  • Cephalization
  • Open Circulatory system
  • Tagmatization
  • Exoskeleton made of chitin
  • Jointed appendages
  • Molting
  • Live in almost all habitats on the earth
  • Estimate of 30-100 million species


Subphylum Trilobitomorpha (extinct)

Subphylum Chelicerata- arachnids, horseshoe crabs

Subphylum Mandibulata- Class Crustacea, Insecta, Myriapoda (milipedes, centipedes)

Tagmatization (Tagmata)

The Arthropod Exoskeleton

-Advantages and constraints

Different between Crustacean an Insect

Exoskeleton made from Chitin

Screen Shot 2017-11-01 at 10.33.22 AM

“Chitin” by Wikimedia Commons under CC by 2.0

Three major functions of the Exoskeleton

  • Protection from predators
  • Prevention from desiccation
  • Locomotion (attachment sites for muscles)

Sclerotization: Hardening of the procuticle after molting (tanning)

Sclerites: Different segments of body parts covered by exoskeleton plates

Joints: Are places that are thing and flexible

Appendages– legs, wings, antennae, mouth parts etc.

Ecdysis– controlled by the hormone ecdysone

-Complete digestive tract

-Malpigian tubules- used so they do not dry out. Dry waste

Nerves and Muscles- Arthropods have striated muscle

Subphylum: Crustaceans

-Lobsters, crabs, barnacles




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