biol 11 lesson 3 feb 7 - ch. 26 cnidarians
DESCRIPTION
Biology 11Animal Biology unit - InvertebratesMiller, K.R. & Levine, J. (2000). Biology (5th ed.). New Jersey: Prentice Hall. Ch. 26: Sponges, Cnidarians, and Unsegmented Wormspp. 564-569.TRANSCRIPT
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!