BIOL 321 Lecture Notes - Lecture 24: Pancrustacea, Hexapoda, Arthropod
6 Dec 2016
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Document Summary
Example being silverfish, probably descendants of early insects without wings. Wings arise from the 2nd and 3rd thorax (mesothorax and metathorax). Wings are largely just exoskeleton and are reinforced by wing veins which are tracheal tubules and a bit of living tissues that parallels the tracheal tissues. Key evolutionary innovation: allows for insects to live in places that they couldn"t have without wings. Advantages of flight: dispersal: move from one area to another (eg. when resources have been depleted, predator avoidance: just fly away, searching for mates, migrations: areas suitable for feeding or areas suitable for overwintering. Origins of wings: tergal (paranotal) lobes theory, derivatives of appendages. Mandibles are heavily scleritized for biting off seed or whatever. In insects, the 2nd pair of maxillae are fused together along median line and called the labium. Hypopharynx is sort of a tongue (with salivary glands running down.
