Homework from last class:• Complete Section Review 26-3 questions 1-5 (p.

569)

• Complete Cnidaria crossword puzzle

• Label and colour Cnidaria diagram handout — I will provide you with a new handout (due Tues, Feb. 15)

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

• Study for Quiz on Phylum Cnidaria next class!

Cnidaria quiz

•You have 10 minutes to write the quiz.

Good luck!

Section Review 26-3 (p. 569):1) What is a cnidarian? What kind of symmetry

do cnidarians have?

A cnidarian is a soft-bodied aquatic animal exhibiting radial symmetry that has stinging tentacles containing nematocysts.

Section Review 26-2 (p. 563):2) Give an example of each class of cnidarians.

1) Class Hydrozoa: hydra, Portuguese man-of-war

2) Class Scyphozoa: jellyfish

3) Class Anthozoa: sea anemone, coral

E.g. Hydra

E.g. jellyfish

E.g. Sea anemones and coral

Section Review 26-3 (p. 569):3) Describe the life cycle of a typical cnidarian.

1) A fertilized egg develops into a ciliated larva

2) The larva develops into a polyp

3) The polyp produces medusae asexually by budding

4) Eggs from female medusae are fertilized by sperms from male medusae

12

3

4

Section Review 26-3 (p. 569):4) Discuss symbiotic relationships and other

interactions between cnidarians and other living things.

• Anthozoans provide habitat for photosynthetic protists or bacteria; they in turn provide food for the anthozoan.

• Sea anemones and small fish are symbiotic.

• Coral reefs provide a home for many animals and help protect shore habitats from erosion.

Section Review 26-3 (p. 569):5) A medusa usually has specialized sense

organs. It may also have nerves that are organized into rings that encircle its body and structures that control body contractions. Explain why a medusa needs a more complex nervous system than a polyp.

(Hint: How does the lifestyle of a medusa differ from that of a polyp?)

Medusae are motile and thus need a nervous system that can coordinate movement and respond to stimuli quickly and effectively.

Introduction to Planaria• http://www.youtube.com/watch?v=w0QzSYQGsnA

Phylum Platyhelminthes:Flatworms

Chapter 26: Sponges, Cnidarians, and Unsegmented Wormspp. 570-575

Introduction to Flatworms• Phylum Platyhelminthes: platy = flat, helminth =

worm

•Simplest animals with bilateral symmetry

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

•Show the beginnings of cephalization (i.e. a head)

•Can be free-living or parasitic

ectoderm

mesodermendodermgastrovascul

ar cavity

Classes of Flatworms1) Class Turbellaria

▫ Free-living, usually small, freshwater▫ Predators or scavengers▫ Example member: Planaria

Classes of Flatworms

2) Class Trematoda (flukes)• Parasitic (internal parasites) often infect

blood and organs• Often have more than 1 host• Reduced digestive and nervous systems

• Example member: blood flukes (Schistosoma); has 2 hosts (p. 573)

• humans = primary host • snails = intermediate host

Class Trematoda - blood fluke Schistosoma

Intermediate host: snail

primary host: human

p. 573

Classes of Flatworms

3) Class Cestoda (tapeworms) • Long and flat parasites• Head is called scolex• Narrow neck region that divides to form

proglottids (contain huge numbers of sperm and eggs) p. 575 (beef tapeworm)

• No digestive or nervous systems• Highly developed reproductive system

proglottid

scolex

Form and Function of FlatwormsDigestive system: • Gastrovascular cavity where food is broken

down• Two-way digestive system• Food and wastes enter/exit the pharynx

Pharynx = opening to the gastrovascular

cavity

e.g.Planaria

Respiratory system:Circulatory system:

Excretory system: • Flame cells - primitive excretory

structures that get rid of excess water• Metabolic wastes diffuse through the skin

• No organized systems for these• O2, CO2 diffuse through the ectoderm

auricle

Nervous system:• Fairly well-developed• Has primitive “brain” and 2 ventral nerve cords• Ocelli (aka eyespots) to detect light/dark• Two auricles sensitive to touch and chemicals

Musculoskeletal system:• Muscles and cilia on ventral surface for

locomotion

Planaria nervous system

If you cut a part off, it

grows into a new worm!

Planaria reproductive system

La fin!Activity: Phylum Platyhelminthes Question Worksheet

Phylum Platyhelminthes Colouring/Labeling Worksheet

New Phylum Cnidaria Colouring/Labeling Worksheet

Activity:1) Work on the Platyhelminthes question

worksheet

2) Work on the Platyhelminthes labeling/colouring worksheet

▫ Make a legend of the colours you use on your diagram

e.g. Digestive system

Respiratory system

3) Work on the new Phylum Cnidaria labeling/colouring worksheet.

Homework for next 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!