Homework from last class:• Complete Section Review 26-2 questions 1-3 (p.

563)

• Fill in and colour the sponge diagram worksheet

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

• Study for Quiz on Phylum Porifera next class!

• Return Field Trip form by Feb. 7 – Vancouver Aquarium!

• Bring pencil crayons to class for all the colouring ahead!

Sponge quiz

•You have 10 minutes to write the quiz.

Good luck!

Section Review 26-2 (p. 563):1) How do sponges differ from other animals?

How do they feed, respire, and eliminate wastes?Sponges:

▫ do not have a mouth or digestive tract (gut)▫ no true tissue layers (endoderm, ectoderm, mesoderm)

or organ systems

Feed: Collar cells catch food particles and engulf them; amoebocytes take food particles from the collar cells and carry them to other parts of the sponge.Respiration and excretion: The current of H2O that flows through the body of a sponge delivers O2 to the cells and removes CO2 and cellular wastes.

Section Review 26-2 (p. 563):2) How are sponges providing useful to medical

science?

Sponges produce chemicals that can be used to fight bacteria, viruses, and other disease-causing microorganisms.

Section Review 26-2 (p. 563):3) Why are sponges thought to be an evolutionary dead end?

No other groups of organisms have evolved from sponges.

Warm-up: The Box Jellyfish• http://www.youtube.com/watch?v=hUTr0ufJGgo

Phylum Cnidaria: Jellyfish, Sea Anemones, and CoralsChapter 26: Sponges, Cnidarians, and Unsegmented Wormspp. 564-569

Introduction to Cnidarians•Soft-bodied animals

•Radially symmetrical

•Body has 2 cell layers (ectoderm and endoderm) separated by a layer of jellylike (mesoglea)

•Have stinging tentacles arranged in a circle around mouth

•Most have life cycles that include 2 stages:▫Polyp▫Medusa

gastrovascular cavity

endoderm

mesoglea

ectoderm

Medusa• free-

floating• motile

Polyp• attached• sessile

Both forms have a gastrovascular cavity with only one opening food enters the same hole that wastes go out! (a two-way digestive system)

Classes of Cnidarians1) Class Hydrozoa

▫Mostly polyps; short medusa stage▫Often live in colonies, where specialized

polyps perform particular functions Example members: hydras (small, freshwater),

Portuguese man-of-war (huge, marine; colonial)

2) Class Scyphozoa (jellyfish)▫Medusa is dominant stage; very short polyp stage

Classes of Cnidarians3) Class Anthozoa (sea anemones and corals)

▫ Polyps only, no medusa stage▫Corals create protective “cups”; anemones

don’t▫ Some corals are reef building and are

ecologically important

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

broken down

• Food is absorbed and further digested by the cells that line the gastrovascular cavity (gastroderm (endoderm) cells)

• Cnidoblast cells (in tentacles) contain nematocysts poison darts that spring out when touched and paralyze prey • Tentacles then pull food into mouth

Form and Function of CnidariansRespiratory system:Circulatory system:Excretory system:

• O2, CO2, and wastes get in and out of cells by diffusion through gastrovascular cavity and epidermis (ectoderm).

Direct exchange with surrounding water.

• No organized systems for any of these• No need since cnidarians are only a few layers thick

for metabolic waste

Form and Function of Cnidarians

Obelialife cycle

Life cycle of a Cnidarian

Ecology of Cnidarians Sea anemones and small fish are symbiotic Coral reefs are a major habitat for many

organisms They also protect the land from erosion Coral reefs are very sensitive to pollution! Some cnidarians are used in medical

research (toxins)

Fertig!Activity:

Sponge and Cnidaria Crossword puzzleCnidaria colouring worksheet

Activity:

•Work on the Sponge and Cnidaria Crossword Puzzle – vocabulary review from the last 2 classes▫Helpful for homework and quizzes!

•Colour your Cnidaria worksheet according to the colour coding scheme for body systems on the Animalia Unit outline

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

569)

• Complete Cnidaria crossword puzzle

• Label and colour Cnidaria diagram handout

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

• Study for Quiz on Phylum Cnidaria next class!