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Anatomy of Animals


Arthropods

Segmented animals have repeating units. This has led to specialization of parts over evolutionary time because the different segments could become specialized for different purposes. The ancestral arthropods probably had many segments with a pair of appendages on each segment. These animals belong to the classes Chilopoda (see Figure 15C) and Diplopoda (it has 2 segments fused into one - 2 pairs of legs for each segment). The segments of arthropods today (classes Arachnida and Insecta,
Arthropods Bumblebee Figure 15B and D) are often fused into regions such as the head, thorax, and abdomen. The head and thorax may be fused to form a cephalothorax (class Crustacea, Figure 15A). Since insects comprise one of the largest animal groups - both in number of species (about 1 million) and in number of individuals, the grasshopper will be used as the anatomical example (Figure 16e), also see a crayfish anatomy in Figure 16b. Figure 16a captures an image of

Figure 15 Arthropods
[view large image]

Figure 16a Flight of the Bumblebee [view large image]

the flight of bumblebee.


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