This lifeform is widespread in North America.

Bristletails (Order Thysanura) are among the most primitive common insects. They are usually wingless and able to crawl or run quickly. About 250 species exist worldwide; of these, 40 are found in North America.

Insects (Class Insecta) are the most successful animals on Earth if success is measured by the number of species or the total number of living organisms. This class contains more than a million species, of which North America has approximately 100,000.

Insects have an exoskeleton. The body is divided into three parts. The foremost part, the head, usually bears two antennae. The middle part, the thorax, has six legs and usually four wings. The last part, the abdomen, is used for breathing and reproduction.

Although different taxonomists divide the insects differently, about thirty-five different orders are included in most of the systems.

The following abbreviated list identifies some common orders of the many different orders of insects discussed herein:

   Odonata:      Dragon and Damsel Flies
   Orthoptera:   Grasshoppers and Mantids
   Homoptera:    Cicadas and Misc. Hoppers
   Diptera:      Flies and Mosquitoes
   Hymenoptera:  Ants, Wasps, and Bees
   Lepidoptera:  Butterflies and Moths
   Coleoptera:   Beetles

Jointed Legged Animals (Phylum Arthropoda) make up the largest phylum. There are probably more than one million different species of arthropods known to science. It is also the most successful animal phylum in terms of the total number of living organisms.

Butterflies, beetles, grasshoppers, various insects, spiders, and crabs are well-known arthropods.

The phylum is usually broken into the following five main classes:

   Arachnida:      Spiders and Scorpions
   Crustacea:      Crabs and Crayfish
   Chilopoda:      Centipedes
   Diplopoda:      Millipedes
   Insecta:        Insects

There are several other "rare" classes in the arthropods that should be mentioned. A more formal list is as follows:

   Sub Phylum Chelicerata

     C. Arachnida:      Spiders and scorpions
     C. Pycnogonida:    Sea spiders (500 species)
     C. Merostomata:    Mostly fossil species

   Sub Phylum Mandibulata

     C. Crustacea:      Crabs and crayfish
      
   Myriapod Group

     C. Chilopoda:      Centipedes
     C. Diplopoda:      Millipedes
     C. Pauropoda:      Tiny millipede-like
     C. Symphyla:       Garden centipedes

   Insect Group

     C. Insecta:        Insects

The above list does not include some extinct classes of Arthropods such as the Trilobites.

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.