Phylum Arthropoda

click to find the answer to today's question The exoskeleton of arthropods is secreted by the epidermis, however, the exoskeleton must be larger than the animal to give it room to grow. How does an arthropod produce an exoskeleton that is larger than its body?

Phylum characteristics: link to an Internet Website
  • Jointed appendages
  • Segmented body
  • Exoskeleton
  • Ventral nervous system
  • Open circulatory system
  • Sensory receptors
An Arthropod Which phylum characteristics are visible in this picture?

Three quarters of all animal species belong to the Phylum Arthropoda. Their jointed appendages and segmented exoskeleton are the most distinctive arthropod traits. Unlike the muscles in the animals we have studied so far, arthropod muscles do not form continuous sheets. Arthropod muscles occur in bundles that are attached on either side of the joints in the exoskeleton. This gives arthropods a vastly improved system of locomotion.

The exoskeleton is composed of a tough calcium containing compound called chitin (KITE - 'n). The exoskeleton is composed of three layers, secreted by the epidermis that lies just beneath:

Once formed, the exoskeleton cannot enlarge as the soft body tissues grow. As the body grows, it puts more and more pressure against the inside of the exoskeleton. Eventually, this pressure triggers the process of molting, the splitting of the old exoskeleton and formation of another.

The steps of the molting process are: link to a local picture

click to find the answer to today's question To what part of the body are insect wings attached?

Arthropod predators: link to an Internet Website

The arthropod predators of insects and mites include beetles, true bugs, lacewings, flies, midges, spiders, wasps, and predatory mites. Many of these are being successfully used as a "biological" control of pests.

Arthropod classification:

All living members of the Phylum Arthropoda are in these three subphyla:

Research Links:










When an arthropod is ready to secrete a new exoskeleton it will expand its body by taking in air or water, depending on its environment. The animal will retain this expanded body until the new exoskeleton hardens. When the water or air is released, the body shrinks, leaving space for the animal to grow normally inside the new exoskeleton.










When insects have wings, they are attached to the cephalothorax.