Homework from last class:• Complete the Platyhelminthes question

worksheet

• Complete the Platyhelminthes labeling/colouring worksheet

• Complete the new Cnidaria labeling/colouring worksheet

• Read over class notes and check out the class blog: http://msoonscience.blogspot.com/

• Study for Quiz on Phylum Platyhelminthes next class!

Flatworms quiz

•You have ~10 minutes to write the quiz.

Good luck!

Phylum Nematoda:Roundworms

Chapter 26: Sponges, Cnidarians, and Unsegmented Wormspp. 575-578

Biology fun fact of the day:

A single rotting apple can contain as many as 90,000 roundworms!

• Phylum Nematoda

•Bilateral symmetry

•Body has 3 cell layers • ectoderm (outer)• mesoderm (middle)• endoderm (inner)

• Pseudocoelom – a fluid-filled space between the mesoderm and internal organs

Introduction to Roundwormspseudocoelo

m

endoderm

mesoderm

ectoderm

Introduction to Roundworms•Simplest phylum to have a complete one-way

digestive tract (mouth anus)

•Can be microscopic to 1 m long

•Exist practically everywhere! Many found in soil

•Mostly free-living, some parasitic

• We will not focus on any particular classes of nematodes • We will use Ascaris as our model nematode

Form and Function of RoundwormsDigestive system: • Complete digestive tract with an opening at

each end intestine (not a gastrovascular cavity)

e.g. Ascaris

Respiratory system:Circulatory system:

Excretory system: • Excretory canals with 2 excretory pores

(openings) near anterior end

• No organized systems for these• O2, CO2 diffuse through the ectoderm/cuticlecuticle – protective outer covering on

nematodes (and parasitic flatworms)

Nervous system:• Head• Dorsal and ventral nerves

Musculoskeletal system:

• Longitudinal muscles only

Ascaris female

Ascaris

male

Ecology of Flatworms and Roundworms

• Free-living flatworms and roundworms are usually small and don’t affect humans much

• We focus on parasitic worms can cause horrific diseases

Flatworm parasites

Roundworm parasites

FlukesTapeworms

Ascaris Hookworm

Filarial wormsTrichinella

Guinea wormsEye worms

Activity:

Plenty of Parasites – the dating game!

The Parasite Dating Game!The contestants:

5 international parasitic worm beauties! (lucky you!)

Your quest:

1) In groups of 5, you will ‘date’ your parasitic worm get to know everything about it! (all its adorable quirks)

2) Your group will be split up and you will join a new group tell your new group all about your parasitic worm date (all the juicy gossip)

3) Individually fill out a summary sheet covering all 5 parasitic roundworm contestants, then choose your favourite!

Hand in at the end of class

Homework for next class:• Complete Section Review 26-4 questions 1-5

• Complete the Nematoda question worksheet

• Complete the Nematoda labeling/colouring worksheet

• Complete Plenty of Parasites – The Dating Game summary sheet (notes on parasitic worms on the blog)

• Read over class notes and check out the class blog:http://msoonscience.blogspot.com/

Hydra and Planaria lab next class!