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The Amazing Arthropods
More than 80% of the earth's animals are arthropods!
Think of lobsters, spiders, beetles, centipedes, and millipedes.
They all look different, but their bodies are built the same way.
Believe it or not, they all belong to the same group of animals--the
arthropods, from the Latin "Arthropoda," meaning "jointed
legs."
Arthropod Bodies
Arthropod bodies are made up of
three sections with segments
that are fused together. Just like humans, the left and right sides of
their bodies match, which means that they are bilaterally symmetrical. These
sections (technically known at "tagma") have different numbers of
segments fused together. For example, there are three segments in the thorax.
Exoskeleton:
the arthropod "skeleton"--a
shell-like body wall forming the outside of the body and moved
by internal muscles.
Head:
contains the arthropod's eyes, mouth, antennae, and and brain. There are three
sections to the brain.
Antennae:
the primary sense organs used for touching, smelling,
and feeling vibrations. For some insects, antennae act in place
of eyes.
Thorax:
powers the arthropod; all leg and wing muscles are found
here.
Abdomen:
contains the digestive and reproductive organs, oxygen-supplying
spiracles/gills/or booklungs, and sensory organs such as cerci.
Rotate a Grasshopper 360 Degrees
1.7 mb Quicktime VR File
(Note: To rotate the grasshopper, click and drag the cursor across the screen.)
Bilateral symmetry:
bilateral symmetry means having matching left
and right sides of the body. This promotes forward movement, allowing the
head's sensory organs, the eyes and antennae, meet the world first.
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