Diversity of Life

1. Diversity of Life Part II: Invertebrates

2. What is an animal? • Celltissueorganorgansystemorganism • Major functions: obtain food and oxygen, keep internal conditions stable, move and reproduce • Vertebrates (have backbone) and invertebrates(do not have backbone – 97%) • Symmetry: Balanced arrangements of parts -Bilateral, radial, none

3. Sponges • Live in water (oceans, lakes, rivers) • No symmetry, no tissues or organs • Gets food by filtering the water that flows over it • Reproduce by budding or sexual reproduction (sperm released into water and fertilize eggs from another sponge)

4. Cnidarians • Ex: Jellyfish, corals and sea anemones • Use stinging cells to capture food and defend themselves • 2 Body structures: either polyp or medusa • Both have radial symmetry, central hollow cavity and stinging cells • Some just one body type, others go through stages of both • Obtain food by first stinging then using tentacles • Food goes to central cavity, digests and undigested food expelled out the mouth

5. Worms • Invertebrates with long, narrow bodies • Bilateral symmetry, head and tail end • Have tissues, organs and body systems • Simplest organisms with a brain (detect objects, food, mates, responses to environment with sense organs) • Reproduce sexually (contain both sex organs, exchange sperm) and asexually (breaking into pieces)

6. Types of worms • Flatworms: flat and soft as jelly. Most are parasites (lives inside or on another organism -host), some are free-living (Ex: Tapeworm) • Roundworms: Live in any moist environment, cylindrical bodies, have digestive system that is open at both ends (food travels 1 direction) • Segmented worms: Bodies made up of many linked sections (ex: earthworm), closed circulatory system (blood vessels). Quicker blood flow

7. Mollusks • Ex: Clams, oysters, scallops, snails, squid • Invertebrates with soft bodies often protected by hard outer shell • Has a thin layer of tissue called a mantle that covers its internal organs, and has an organ called a foot. • Open circulatory systems • Water mollusks have gills for oxygen • Gastropods, Bivalves and cephalopods

8. Types of mollusks • Gatropods: (snails, slugs) single external shell or no shell. Move with foot that secretes mucous. • Bivalve: (oysters, clams ) 2 shells held together by hinges and strong muscles. Uses foot to move. (Pearls form to cover unwanted grain of sand that gets stuck in shell) • Cephalapods: (octopus) ocean dwelling mollusk whose foot is adapted to form tentacles around its mouth. CLOSED circulatory system (only mollusks to have this)

9. Arthropods • Invertebrates that have external skeleton, segmented body, and jointed attachments called appendages • Exoskeleton (waxy, waterproof covering):keep them from drying out, and protection • First animals to live on land • Molts when it needs to get a new exoskeleton (b/c growing)

10. Types of Arthropods • Crustaceans: 2-3 body sections, 5+ pairs of legs, 2 pairs of antennae (crayfish) • Arachnids: 2 body sections, 4 pairs of legs, no antennae (spiders, scorpians) • Centipedes and Millipedes: 2 body sections and many pairs of legs • Insects: 3 body sections(head, thorax, abdomen), 6 legs, 1 pair antennae, 1-2 pairs of wings

11. Echinoderms • Invertebrates with an internal skeleton (endoskeleton) and a system of fluid-filled tubes called a water vascular system. • Move using water vascular system squeezing water into sticky tube feet • Sea stars, sea urchins, sea cucumbers