Phylum key (cont.)Key to the Arthropods
Class Insecta (Insects) - Most will have three pairs of legs (Fig. 1), although, the Diptera larvae, may have no legs (Fig. 2). The adults generally have functional wings (Fig. 3), but larvae can have wing pads or they can lack wings (Fig. 2).
Class Arachnida (Water mites and Spiders) - They usually will have four pairs of legs (Fig. 4). There are no antennae present (Fig. 5).Overall body appears as in Figure 6.
Class Malacostraca (Crayfish and Scuds) - Appendages on all segments except for the last segment.
Class Ostracoda (Ostrocods) - The body is laterally compressed and encased by a shell-like bivalve carapace (Fig.10). Overall body appears as in Figure 11.
Class Branchiopoda - The body is inside of a sack-like, bivalve carapace (Fig. 12). The last body segment has a postabdominal claw (Fig. 13). Overall body appears as in Figure 14.
Class Maxillopoda – On the anterior portion of the body a single, simple eye is visible (Fig. 15). The body has an overall appearance like in Figure 16.