1. Invertebrates (Sponges, Cnidarians,Worms, Mollusks, Arthropods, Echinoderms)

2. I. Sponges A. Phylum Porifera a. asymmetric
b. filter feeders – take in tiny particles of food from water
1. pores - openings where water enters
2. choanocytes – cells with a flagella that move water through sponge
3. osculum – a large opening where water and wastes exit

3. c. spicules – form simple skeleton d. Internal fertilization
e. many other organisms can live inside sponge (mutualism)
spicules

4. Body of a Sponge

5. Cnidarians

6. II. Cnidarians Phylum Cnidaria ex: jellyfish, hydra, corals
a. radial symmetry
b. carnivores
c. nematocysts - poison filled stinging cells that paralyze or kill prey
d. gastrovascular cavity – for digestion; single opening
e. transport materials by diffusion
Cnidarians are carnivorous animals that have stinging tentacles arranged around their mouths. Stinging cells called cnidocytes are used to capture and paralyze prey.

7. f. nerve net – many nerve cells that detect stimuli
g. hydrostatic skeleton – layer of muscles that allow movement
h. external reproduction – separate sexes
i. many other organisms live on corals (mutualism)

8. B. Two Stages of Life Cycle
b. Medusa  motile, bell shaped body with the mouth on the bottom & tentacles hanging around it
a. Polyps  mouth points upward with arm-like tentacles surrounding it; sessile

9. III. Flatworms Phylum Platyhelminthes ex: tapeworms, flukes
a. bilateral symmetry
b. simplest worm
c. very flat (< 3mm thick)
Flatworms are the simplest animals to have three embryonic germ layers—ectoderm, endoderm, and mesoderm.

10. d. no coelom – body cavity not from mesoderm
e. pharynx – muscular tube near mouth; important in digestion
f. diffusion – respiration, excretion, and circulation
g. carnivores
h. some are parasites
i. flame cells – remove excess water and wastes from body

11. j. ganglia – groups of nerve cells
k. eyespot – detects changes in light
l. hermaphrodite – has both male and female reproductive parts
m. sexual and asexual reproduction

12. IV. Roundworms Phylum Nematoda ex: hookworms
a. have a pseudocoelom – body cavity between endoderm & mesoderm layers
Roundworms such as hookworms are unsegmented worms that have a pseudocoelom and a digestive system with a mouth and an anus.

13. b. 2 openings (mouth and anus)
c. predators
d. diffusion
e. ganglia – nervous system
f. muscles & hydrostatic skeleton
g. sexual reproduction (male and females)

14. h. parasites
1. ascaris – intestine parasite
2. hookworms – consume blood and enter through foot

15. Filarial worms cause elephantiasis

16. V. Segmented Worms Phylum Annelida ex: earthworm, leeches
a. septa – body segments
b. true coelom – body cavity formed from mesoderm

17. c. digestion
1. pharynx
2. crop – stores food
3. gizzard – grinds food
d. closed circulatory system
e. respiration through gills
f. nephridia – excretion
g. brain and nerve cords
h. hydrostatic skeleton
i. Clitelum – thick ring where eggs and sperm are released into

18. j. leeches – parasites that suck blood

19. k. Earthworms important to soil ecology (mix soil, wastes provide nutrients for plants); important to food chain
Friend or Foe?
FRIEND!
~ They are decomposers
~ Indicate healthy soil
~ Mix soil
~ Provide channels for root growth