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Unit 8 Invertebrates

Unit 8 Invertebrates. Ch. 28 Arthropods & Echinoderms. What Is an Arthropod?. Arthropods have a segmented body, a tough exoskeleton, & jointed appendages Includes: insects, crabs, centipedes, & spiders. What Is an Arthropod?.

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Unit 8 Invertebrates

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  1. Unit 8 Invertebrates Ch. 28 Arthropods & Echinoderms

  2. What Is an Arthropod? • Arthropods have a segmented body, a tough exoskeleton, & jointed appendages • Includes: insects, crabs, centipedes, & spiders

  3. What Is an Arthropod? • Exoskeleton - tough external covering, made of chitin, it protects & supports • Chitin - a carbohydrate • Appendages - structures such as legs & antennae that extend from the body wall

  4. Evolution of Arthropods • The evolution of arthropods, by natural selection & other processes, has led to fewer body segments & highly specialized appendages for feeding, movement, & other functions

  5. Growth & Development in Arthropods • When they outgrow their exoskeletons, arthropods undergo periods of molting • Molting - when an organism sheds its entire exoskeleton & makes a larger one to take its place • It is controlled by the arthropod’s endocrine system, which regulates body processes by hormones

  6. Groups of Arthropods • Arthropods are classified based on the # & structure of their body segments & appendages - particularly their mouth parts • The 3 major groups of arthropods are crustaceans, spiders & their relatives, & insects & their relatives

  7. Groups of Arthropods • Crustaceans typically have 2 pairs of antennae, 2 or 3 body sections, & chewing mouthparts called mandibles

  8. Groups of Arthropods • Spiders & their relatives have mouthparts called chelicerae & 2 body sections, & nearly all have 4 pairs of walking legs

  9. Groups of Arthropods • Insects & their relatives have jaws, 1 pair of antennae, & unbranched appendages • Includes: centipedes & millipedes

  10. What Is an Insect? • Insects have a body divided into 3 parts - head, thorax, & abdomen • 3 pairs of legs are attached to the thorax

  11. Insect Communication • Insects communicate using sound, visual, chemical, & other types of signals

  12. Insect Societies • Ants, bees, termites, & some of their relatives form complex associations called societies • Society - a group of closely related animals of the same species that work together for the benefit of the whole group

  13. What Is an Echinoderm? • Echinoderms are characterized by spiny skin, an internal skeleton, a water vascular system, & suction-cuplike structures called tube feet • Most adult echinoderms exhibit 5-part radial symmetry

  14. Form & Function in Echinoderms • The water vascular system, which is filled with fluid, carries out many essential body functions in echinoderms, including: respiration, circulation, & movement

  15. Groups of Echinoderms • Classes of echinoderms include sea urchins & sand dollars; brittle stars; sea cucumbers; sea stars; sea lilies & feather stars

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