good morning!! 1.surprise!!! you have a new seat! find your new seat then finish your flap book that...
TRANSCRIPT
Good Morning!!
1. SURPRISE!!! You have a new seat! Find your new seat then finish your flap book that you worked on yesterday (You will have 10 minutes after the announcements to finish).
2. Place in basket when finished3. For early finishers, start working on the
sponges coloring worksheet beside the basket.
Structure and Function
• Approximately 20,000 species!• Acoelomates• Bilateral symmetry• Definite head region and body organs• Very thin• Most parasitic• Some free-living
Where do they live?
• Parasitic: Inside bodies of animals• Free-living: Marine, freshwater, moist land
habitats, underside of rocks in swiftly flowing streams
Feeding
• How do they eat?– Pharynx- tubelike muscular organ that extends out
of their mouths• Releases enzymes that digest prey
– Food sucked into digestive tract– Parasitic have feeding structures:
–Hooks and suckers
Digestion• Reduced digestive system:
– Mouth, pharynx, gastrovascular cavity
• No digestive system in some• Absorb nutrients from their hosts’ intestines• One opening- wastes released through mouth
Respiration and Circulation
• No circulatory or respiratory organs• Use diffusion:
– distribute O2 and nutrients in body
– remove CO2 and wastes
Excretion
• Excretory system- network of small tubes throughout the body
• Flame cells- allow flatworms to excrete waste materials from their bodies
• Substances exit through pores
Response to Stimuli
• Nervous system– 2 nerve cords with connecting nerve tissue
• Looks like the rungs of a ladder
• Swelling containing ganglia that send nerve signals (like a brain)
• Ganglion- nerve cell bodies that coordinates incoming and outgoing nerve signals
Reproduction
• Hermaphrodites- produce both eggs and sperm
• Sexual:– 2 different flatworms exchange sperm– eggs fertilized internally• Marine: zygotes hatch from cocoons released into
the water
Turbellarians• Planaria • 16% of all flatworms• Free-living• Most are marine, though some in fresh water &
terrestrial
Trematodes• Parasitic
– Infect blood or body organs of their hosts
• Example: Shistosoma (parastic fluke)• Cause the disease Shistosomiasis in humans
Cestodes
• Parasitic Tapeworms• Live inside intestines of host• Proglottids- contain reproductive organs• Animals can get tapeworms by eating plants
or drinking water contaminated with tapeworm proglottids