Chapter 30

1. Chapter 30 Arthropods Section 1: Features of Arthropods Section 2: Spiders and Other Arachnids Section 3: Insects and Their Relatives Section 4: Crustaceans

2. Section 1 Features of Arthropods Objectives: • Summarize the evolutionary relationship of arthropods and annelids. • Identify three subphyla of arthropods. • Describe the characteristics of arthropods. • Describe how growth occurs in arthropods.

3. Section 1 Features of Arthropods Jointed Appendages • Jointed Appendages All arthropods have jointed appendages that are modified to perform different functions.

4. Section 1 Features of Arthropods Arthropod Diversity • Classification Arthropods are grouped into three subphyla: Chelicerata, Uniramia, and Crustacea.

5. Section 1 Features of Arthropods Arthropod Body Plan • Segmentation All arthropods have three distinct regions—the head, the thorax, and the abdomen. • Compound Eyes Most arthropods have compound eye, which are made up of thousands of individual visual units. • Exoskeleton Arthropods have an exoskeleton made of chitin. • Molting Molting is a process when arthropods discard the exoskeleton.

6. Section 1 Features of Arthropods Arthropod Body Plan continued • Respiration Air enters the arthropod’s body through spiracles and passes into the tracheae, delivering oxygen throughout the body. • Excretion Arthropods have a unique excretory system called Malpighian tubules that efficiently conserves water and eliminates metabolic wastes.

7. Section 2 Spiders and Other Arachnids Objectives: • Summarize the characteristics of arachnids. • Identify the internal and external characteristics of brown recluse spiders. • Compare spiders, ticks, and mites. • Identify the health threats posed by some arachnids.

8. Section 2 Spiders and Other Arachnids Arachnid Modifications • Chelicerata Members of subphylum Chelicerata have mouthparts, called chelicerae, that are modified into fangs or pincers. • Spiders Spiders have a head and a cephalothorax, no antennae, six or eight pairs of simple eyes, a pair of fangs and pedipalps, and four pairs of walking legs.

9. Section 2 Spiders and Other Arachnids Scorpions and Mites • Scorpions Scorpions have pedipalps modified into large, grasping pincers. A stinger is located at the end of their abdomen. • Mites Mites have body parts that are fused to form an unsegmented body. Many mites transmit diseases.

10. Section 3 Insects and Their Relatives Objectives: • Describe the characteristics of insects. • Compare complete and incomplete metamorphosis. • Identify the external and internal structures of the Eastern Lubber grasshopper. • Compare millipedes and centipedes with insects.

11. Section 3 Insects and Their Relatives Insect Diversity • Species of Insects Insects make up more than half of all named animal species. • Insect Body Plan All insects have a body plan with three body sections (head, thorax, and abdomen), three pairs of legs (all attached to the thorax), and one pair of antennae. • Insect Life Cycle The life cycles of insects are complex and involve a process of change called metamorphosis, during which larvae change into the adult insects.

12. Section 3 Insects and Their Relatives Insect Diversity continued • Flight Insects were the first animals to have wings. • Social Insects Hymenoptera and Isoptera have elaborate social systems. • Insect Relatives Centipedes and millipedes are related to insects, but they have numerous segments.

13. Section 4 Crustaceans Objectives: • Summarize how crustaceans and insects are similar and dissimilar. • Describe the body plan of decapods.

14. Section 4 Crustaceans Crustacean Habitats • Characteristics Most crustaceans have branched appendages, two pairs of antennae, three chewing appendages, walking legs attached to the thorax, and gills. Like insects, crustaceans have jaws called mandibles. Crustaceans have a distinctive larval form called a nauplius and crustaceans live in the world’s oceans.

15. Section 4 Crustaceans Terrestrial Crustaceans • Common Examples The most widespread terrestrial crustaceans are pill bugs and sow bugs.

16. Section 4 Crustaceans Aquatic Crustaceans • Copapods and Krill Copepods and krill, which are tiny marine crustaceans, are the chief food of many marine species. • Decapods Large marine crustaceans such as shrimps, lobsters, and crabs, have five pairs of legs. • Sessile Crustaceans Barnacles are sessile as adults.