1. Unsegmented worms (flatworms & roundworms)

2. Kingdom Animalia Overview
First animals with bilateral symmetry
and cephalization!

3. General Characteristics
Eukaryotic, multicellular, heterotrophic
Includes Planaria (free-living) and parasites: fluke and tapeworm
3 germ layers: endoderm, mesoderm & ectoderm
Acoelomates (no central body cavity)
Bilateral symmetry – has symmetry in only one direction
Cephalization! Nervous tissue is concentrated in one end of organism.
Two way digestive system (one opening)
Hermaphrodites
Regeneration/Fragmentation

4. 3 Classes of Planarians Turbellaria – free-living
Trematoda – Parasites
Flukes
Cestoda – Parasites
Tapeworms

5. Structure
Planaria

6. Structure - Planaria Pharynx  sucks food into gastrovascular cavity
Mouth  takes in and expels digested food. On stomach, not on head!
Brain control centre of nervous system – collection of ganglia
Eyespot  senses light, lateral flaps allow smelling
Gastrovascular cavity  enzymes break down food, diffuses into cells (many branches along body)
Nerve cord control muscles

7. Structure Tapeworm structure
Prot0glottid = unit of the reproductive system
Scolex = head region

8. Feeding & Excretion
Carnivores (feed on aquatic animals) or scavengers (feed on dead animals)
Use pharynx to suck food into gastrovascular cavity
GV cavity forms branching intestine
Enzymes in GV cavity breakdown food, then diffuses into tissues
Waste expelled through mouth
Parasitic forms have no digestive tract (food is digested already by host). Food absorbed via diffusion

9. Response Movement simple “brain” (collection of ganglia)
Nerve cords down length of body
Ocelli (eye spots) – detect light & dark
Cells to detect food source, direction of water flow
Parasitic forms – no nervous system
Cilia on epidermal cells glide along a film of mucus they secrete
Muscle cells controlled by nervous system allows twisting and turning
Parasitic – no need for movement (constant supply of food)
Movement

10. Circulation & Respiration
Rely on diffusion for transport and for gas exchange
Some use flame cells for reproduction
Reproduction
Most free-living (non-parasitic) are hermaphrodites (sexual reproduction)
Some: asexual reproduction through fission
Parasites – complicated life cycles. Sexual reproduction, no fission

11. Reproduction – tapeworm

12. Reproduction – liver fluke

13. Swimmer’s itch

14. What are at least 3 ways flatworms are more complicated than Cnidarians?
What is the scolex?
How do tapeworms attach to a host? Where do they attach?
How does the shape of the flatworm allow it to rely on diffusion for respiration?
Describe fragmentation in the planarian.
What is meant by cephalization? Do flatworms show this?
What are the 3 groups of flatworms? Which ones are free-living?
Name the hosts involved in a fluke’s life cycle.
Explain why Platyhelminthes are called flatworms.
How many germ layers do flatworms have? Name them.
Name 2 parasitic flatworms.
What type of digestive system do flatworms have? How many body openings do they have?
Planarians are hermaphrodites. What does this mean?
Do planarians fertilize their own eggs?
Describe the nervous system and sensory structures of the planarian.
Do tapeworms fertilize their own eggs?
Why do tapeworms not need a digestive system?
What are proglottids?

15. Kingdom Animalia Overview
Two-way digestive system
pseudocoelomates

16. General Characteristics
Well defined digestive system with TWO openings
Most are free-living and some parasitic
Unsegmented worms with tapering ends
Bilateral symmetry and cephalization

17. Structure

18. General Characteristics
Well defined digestive system with TWO openings
Most are free-living and some parasitic
Unsegmented worms with tapering ends
Bilateral symmetry and cephalization

19. Feeding
Long tube-shaped digestive tract with a separate mouth and anus creates a one-way digestive system.
food goes in through the mouth, and undigested food is expelled from the anus
Free-living roundworms are often carnivores that eat tiny animals
Some eat algae, fungi, or rotting organic matter
Some attach to the roots of plants and suck out the plant juices

20. Response
simple nervous systems: several ganglia (groups of nerve cells) in head region but no real brain
Nerves attached to the ganglia run the length of the body
Simple sense organs detect chemicals given off by prey or hosts

21. Movement Internal Transport
Longitudinal muscles run in strips down their bodies, and when contracted allow them to move similar to snakes to push their way forward
Internal Transport
Breathe and excrete metabolic wastes through their body walls using diffusion, just like flatworms

22. Reproduction
Roundworms reproduce sexually, and most species have separate male and female sexes
few are hermaphroditic
Fertilization happens inside the female
Parasitic roundworms often have complex life cycles involving two or three hosts