1. Unit 8 Chapter 28 Arthropods

2. What is an Arthropod? Bilaterally symmetrical, segmented coelomates Segmented body, exoskeleton & jointed appendages Appendages = body outgrowths

3. What is an Arthropod? Arthropods must molt (shed exoskeleton periodically) Arthropods have variety of respiration types: gills, tracheal tubes & book lungs Arthropods have complex digestive and excretory systems:  Mandibles (jaws) are used to classify arthropods

4. What is an Arthropod? Arthropods have well-developed senses: Pheromones = chemical odor signals given off by animals (detected by others) Compound eyes = visual structure with many lenses Simple eye = visual structure with only one lens for detecting light

5. What is an Arthropod? Arthropods reproduce sexually:  Some are hermaphroditic, most have internal fertilization  A few have parthenogenesis = new individuals develop from unfertilized eggs Ex: social insects, such as bees, ants & wasps

6. Diversity of Arthropods Arachnids Includes spiders, scorpions, ticks & mites (chiggers) Two body segments & six pairs of jointed appendages, including 8 legs, 2 chelicerae (fangs) and 2 pedipalps (sensors)

7. Diversity of Arthropods Crustceans Includes crabs, lobsters, shrimp, crayfish, pill bugs & barnacles Two body segments & 2 pair of antennae, 5 pair of legs, and numerous “jaw feet”

8. Diversity of Arthropods Millipedes & Centipedes  Many body segments and paired legs  Millipedes are herbivorous, while centipedes are carnivores Horseshoe Crabs  These “living fossils” have remained unchanged for 200 million years

9. Diversity of Arthropods Insects… Most successful class in terms of diversity Includes beetles, butterflies, ants & bees, flies & mosquitoes, and many others Three body segments, 3 pair of legs, one pair of antennae, and wings

10. Metamorphosis Series of changes in body shape and form during life history Incomplete M: 3 stages including nymph (smaller, immature version of adult)

11. Complete M: 4 stages including larva (wormlike creature which eats and grows) and pupa (enclosed structure that changes into adult form)