PESTS AND THEIR RELATIVES
Principal classes into which the phylum Arthropoda is
Plants in their many forms from great trees to tiny
mosses cover the land. The plant kingdom began as
pond scum. Their
microscopic single cells --
descendants are the algae, bacteria and fungi living
This class includes spiders, mites, scorpions,
today. Larger prehistoric plants developed from their
daddy long legs and others. These arthropods usually
smaller ancestors; finally, flowering plants, modern
have mouthparts with two prominent structures that
shrubs, and trees evolved.
end in a needle-like piercing tip. They have four pairs
Forebears of insects were the first animals to
of legs and two body regions: the mouthparts and legs
move onto land -- before plants had flowers. As plants
are attached to the first region; the reproductive organs
developed, so did the insects, feeding on evolving
and digestive system is contained in the second.
plant structures, such as flowers, pollen, nectar,
leaves, bark, stems, roots, and their dead remains.
At the time of early insect development, the land
This class mostly includes aquatic crabs, lobsters,
had a uniform climate: one with moisture and
and shrimp as well as crustacea that dwell on land,
temperature adequate for constant growth. Later, the
pillbugs and sowbugs.
surface land mass (continents) shifted, moving
northward and southward, creating seasons, and setting
the stage for the world as we know it.
This group is made of two classes -- millipedes
and centipedes. The millipedes are many-segmented
and worm-like; they are cylindrical with short
THE INSECT PLAN
antennae and two pairs of legs per segment.
Insects and their Relatives
Centipedes are also many-segmented and worm-like,
Living things are divided into the Plant Kingdom,
but they appear more flattened; with one pair of legs
the Animal Kingdom, and several smaller kingdoms
per segment; antennae and hind legs are long (All legs
that include microscopic life. Insects are in the largest
of the house centipede are very long).
group in the animal kingdom -- the P h y l u m
Arthropoda. In this group the "arthropods" include
spiders, mites, ticks, millipedes, centipedes, crabs,
This class contains the insects: arthropods with
shrimp, and insects.
three body regions -- head, thorax and abdomen. The
head bears a single pair of antennae; the thorax bears
three pairs of legs, usually wings; the abdomen
contains most of the digestive system and the
Arthropod classes have:
a body made of segments, which are
grouped or fused together
Other Divisions Used in Classification
legs, antennae and other appendages
attached in pairs
Classes of arthropods, insects, for example, are
divided into orders. These are distinct groups that look
a hard or tough external covering with
some pliable, or soft parts; an arthropod
very much alike (e.g., the order of moths and
outer body that holds the body together
butterflies, or the order of beetles).
Orders are subdivided into families made up of
and gives it shape. [It performs the
related species. Species of animals can be thought of
same function as the mammal's bony
internal skeleton, and is called an exo-
as "kinds of animals". Very closely related species are
grouped together in a genus. Species or types of
Module One, Chapter 1, Pg 1