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Arthropods. Chapter 28. What is an Arthropod?. Phylum Arthropoda Segmented body with specialized structures Exoskeleton made of chitin Jointed appendages Bilateral symmetry All 3 germ layers 2 digestive openings coelomate. Evolution of Arthropods.
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Arthropods Chapter 28
What is an Arthropod? • Phylum Arthropoda • Segmented body with specialized structures • Exoskeleton made of chitin • Jointed appendages • Bilateral symmetry • All 3 germ layers • 2 digestive openings • coelomate
Evolution of Arthropods • Natural selection, over time, has led to fewer body segments and specialized appendages used for movement, feeding, etc….
Growth & Development of Arthropods • Arthropods undergo periods of molting when they outgrow their exoskeleton • Molting: shedding of entire exoskeleton and making of new one to take its place.
Groups of Arthropods • Classified based on the number and structure of body segments and appendages (usually mouthparts) • Divided into 3 major sub-phyla: • Crustacea • Chelicerata • Uniramia
Crustacea • 2 pairs of antennae • 2 or 3 body segments • Chewing mouthparts (mandibles) • Ex: lobster, shrimp, crabs, barnacles
Chelicerata • Have mouthparts called chelicerae (fangs) • 2 body sections • 4 pairs of walking legs • Ex: spiders, scorpions, ticks
Uniramia • Have jaws • 1 pair of antennae • Unbranched appendages • Ex: centipedes, millipedes & INSECTS
Insects • 3 body parts (head, thorax, abdomen) • 3 pairs of legs on thorax • Ex: ants, beetles, flies, butterflies, bees, wasps, etc…………..