Unit 8 Invertebrates

1. Unit 8 Invertebrates Ch. 26 Sponges & Cnidarians

2. Introduction to the Animal Kingdom • Animals, members of the kingdom Animalia, are multicellular, eukaryotic heterotrophs whose cells lack cell walls

3. What Is an Animal? • Invertebrates - animals that do not have a backbone, or vertebral column • Vertebrates - animals with a backbone

4. What Animals Do to Survive • Animals carry out the following essential functions: feeding, respiration, circulation, excretion, response, movement, & reproduction

5. What Animals Do to Survive • Feeding • Most animals cannot absorb food, instead, they ingest (or eat) it

6. What Animals Do to Survive • Respiration • Whether they live in water or on land, all animals respire, they take in oxygen & give off carbon dioxide

7. What Animals Do to Survive • Circulation • Small animals rely on diffusion to transport nutrients • Large animals have a circulatory system to move nutrients around

8. What Animals Do to Survive • Excretion • Most animals have an excretory system that eliminates wastes, maintaining homeostasis

9. What Animals Do to Survive • Response • Animals respond to events in their environment using specialized cells called nerve cells

10. What Animals Do to Survive • Movement • Most animals are motile, meaning they can move around

11. What Animals Do to Survive • Reproduction • Most animals reproduce sexually, which helps create & maintain genetic diversity in populations • It improves the species ability to evolve when the environment changes

12. Trends in Animal Evolution • Complex animals tend to have high levels of cell specialization & internal body organization, bilateral body symmetry, a front end or head with sense organs, & a body cavity

13. Trends in Animal Evolution

14. Trends in Animal Evolution • Body symmetry • Radial symmetry - similar to a bicycle wheel, any number of imaginary planes can be drawn through the center • Bilateral symmetry - a single imaginary plane can divide the body into 2 equal sides

15. Body Symmetry

16. Trends in Animal Evolution • Cephalization - the concentration of sense organs & nerve cells at the front end of the body

17. What Is a Sponge? • Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls, & contain a few specialized cells

18. Form & Function in Sponges • The movement of water through the sponge provides a simple mechanism for feeding, respiration, circulation, & excretion

19. Ecology of Sponges • Sponges often provide habitats for other organisms

20. What Is a Cnidarian? • Cnidarians are soft-bodied, carnivorous animals that have stinging tentacles arranged in circles around their mouths • They are the simplest animals to have body symmetry & specialized tissues

21. Form & Function in Cnidarians • Cnidarians typically have a life-cycle that includes 2 different-looking stages: a polyp & a medusa

22. Form & Function in Cnidarians • Response • Many cnidarians respond to touch by pulling their tentacles inside their bodies

23. Form & Function in Cnidarians • Movement • Jellyfishes move by means of jet propulsion • The body contracts to force water out, moving the jellyfish in the opposite direction

24. Groups of Cnidarians • Cnidarians include jellyfishes, hydras & their relatives, & sea anemones & corals

25. Groups of Cnidarians • Like many marine organisms, jellyfishes use bioluminescence, or the production of light by an organism, to ward off predators • The entire body becomes bioluminescent when threatened

26. Groups of Cnidarians • Hydras live solely as polyps • Ex.) Portuguese man-of-war

27. Groups of Cnidarians • Sea anemones are polyps that live at all depths of the ocean • Coral reefs are home to many types of organisms & are as diverse as rain forests

28. Ecology of Corals • In normal conditions, algae live within coral tissues, carrying out photosynthesis & giving the coral its green appearance • When stressed by pollutants or increasing temps., these algae can die, so only the clear cells of the coral remain