1. Sponges, Cnidarians, and Ctenophores
Chapter 33

2. Phylum Porifera
Section 33.1

3. Phylum Porifera
Latin for “Pore-Bearing”
Asymmetric Body Structure

4. Sponges Aquatic animals
Represent transition from unicellular to multicellular life
No true tissue or organs
5,000 species (most marine)
Various colors, shapes, sizes, etc.
Adults are sessile

6. Sponge Body Plan:
Two layers of cells separated by mesohyl (jellylike substance)
Body wall forms a hollow cylinder that is open at the top

7. More Sponge Parts:
Choanocytes (collar cells): flagellated cells that draw water into the sponge
Ostia (pores): pores that penetrate the body wall that allow water into the sponge
Osculum: opening at the top of the sponge

8. Sponge Support System
Simple skeleton made up of spongin and/or spicules
Spongin: tough, flexible protein fibers
Spicules: tiny, hard particles of calcium carbonate or silicon dioxide
shaped like spikes
Spicules
Spongin

9. Sponge Anatomy

10. Feeding & Digestion
Filter feeders of plankton and other small organisms
Steps in feeding & digestion:
Choanocytes beat & draw water into ostia
Then collect food from water
Nutrients pass from choanocytes to amoebocytes
Crawling cells that deliver nutrients to rest of the body
Wastes and CO2 diffuse into the water and goes out the osculum
video

11. Water Flow:
Video

12. Asexual Reproduction Regeneration: Budding: regrowth of missing cells
sometimes the bud breaks off the parent and becomes a new organism
or it may remain attached to the parent and develop into a sponge colony

13. Environment gone bad?
Gemmules: food filled ball of amebocytes protected by protein & spicules
Can survive harsh conditions
Similar to endospore of bacteria

14. video Sexual Reproduction
Sperm of one sponge enters pores of a different sponge
Choanocytes engulf the sperm
Sperm transferred to ameobcytes
Then transferred to egg in mesohyl
Egg is fertilized
Swimming larva leaves the sponge and settles on an object to become an adult
video

15. Hermaphrodites
Why doesn’t self-fertilization usually occur in an hermaphroditic species?
Answer:
Less genetic diversity thus less of a change to survive an environmental change (evolution would not occur as much)

16. Phyla Notecards: First side: Opposite side: Phylum name
Example organisms
Drawing of organism
With color!
Opposite side:
Body symmetry
Mobility (adult & larval stages)
Feeding methods
Reproductive methods
Defense mechanisms
Environment/habitat

17. Cnidaria & Ctenophora
Section 33.2

18. Phylum Cnidaria

19. General Characteristics:
Radial symmetry
Have tissues and simple organs
Aquatic (mostly marine)

20. Phylum Cnidaria

21. Body Plans: Medusa: bell-shaped specialized for swimming
Polyp: vase-shaped specialized for sessile living

22. More Body Parts: Two cell layers: Epidermis: outer layer
Gastrodermis: inner layer
Mesoglea:
jellylike material between two layers

23. Continued…
Gastrovascular cavity: center of body with a hollow gut and mouth
Tentacles: flexible extensions surrounding the mouth
Moves food in

24. Feeding & Defense:
Cnidocytes: specialized cells used for defense and capturing prey
Gives the phylum its name!
Nematocyst: organelle within cnidocyte with a long filament and a poison tip
Trigger response
Video

25. Nervous System: Nerve net: diffused web of interconnected nerve cells
No brain
No cephalization
Can respond to stimuli
Nerve net  contractile cell  contraction of whole body
Can control swimming & feeding

26. Classification: Four classes: Class Hydrozoa Class Cubozoa
Class Scyphozoa
Class Anthozoa

27. Class Hydrozoa: Man of War Obelia Hydra
Colonial organisms (combo of polyp & medusa form)
Each organism has a specialized function for the colony
Exception: hydras – only polyps, NOT colonial
Examples: Portuguese man-of-war, hydra, and Obelia
Man of War
Video
Obelia
Hydra

28. Class Cubozoa: Sea Wasp Commonly known as box jellies
Cube shaped medusa
Some have cnidocytes that can cause death to humans
Example: Sea wasps
Sea Wasp

29. Class Scyphozoa: Life Cycle video Commonly known as jellyfish
The medusa form is dominant
Some have poisonous nemotocytes that can cause pain and death
Life Cycle
video

30. Biotechnology with Jellies video

31. Class Anthozoa: Meaning: flower animals Dominant form = polyp
Examples: coral & sea anemone
Some have symbiotic relationships with other species:
Coral with algae
Sea anemone with clownfish
Nemo!
Coral
And
Algae

32. Phylum Ctenophora
Video

33. Distinguishing Characteristics:
Meaning: comb holder
Commonly called comb jellies
Move by beating cilia
Contain colloblasts that secrete a sticky substance that blinds prey
Do not have cnidocytes (like other jellies)

34. Continued…
Apical organ: sensory structure that determines orientation in the water
Bioluminescence: production of light through chemical reactions

35. Phyla Notecards: First side: Opposite side: Phylum name
Example organisms
Drawing of organism
With color!
Opposite side:
Body symmetry
Mobility (adult & larval stages)
Feeding methods
Reproductive methods
Defense mechanisms
Environment/habitat

36. Class Notecards: First side: Opposite side: Class name
Example organisms
Drawing of organism
With color!
Opposite side:
Unique characteristics
Description of representative organism
Info about an organism listed in the book
Environment/habitat