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.

Kingdom: AnimaliaPhylum: Platyhelminthes

(Flatworms)Chapter 25 Section 1

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

• What do they eat?– Dead, or slow-moving organisms– Eat blood and other body tissues

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

http://www.google.com/url?sa=i&rct=j&q=planaria&source=images&cd=&cad=rja&docid=oa26t0IgEPpIwM&tbnid=5axjZUCpgdRGtM:&ved=0CAUQjRw&url=http%3A%2F%2Fallthesciences.blogspot.com%2F2010%2F05%2Fpower-of-planaria.html&ei=JDoVUdXoO4Lo8gSJ8YHYDA&psig=AFQjCNEVnqsW0qTIcUM6g6rmeJ_FEQwWxA&ust=1360431962158625

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

• Asexual:– Regeneration- regrow damaged or missing body

parts

Movement

• Contract muscles in body wall• Glide using cilia and mucus covering

Diversity

• 3 Classes:Free Living:–Turbellaria Parasitic:–Trematoda –Cestoda

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

Life Cycle of Schistosoma

48 hours to find host

& urine

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

Life Cycle of Beef Tapeworm

Life Cycle of Pork Tapeworm