1. Porifera and cnidaria

3. Phylum Porifera (sponges)

4. Appearance Symmetry: Asymmetric (usually)
2 layers of independente cells (not real tissue***):
a) pinacocytes: cell plates on the exterior that contract
b) choanocytes: flagellated cells on the inside, also called collar cells
Spicules: thin tiny fibres made of glasslike silica or CaCO3 that forms the delicate skeleton on the sponges.
Some have a protein called spongin. (softer)

5. Structure pinacocytes Choanocyte (outside) (inside) osculum amibocytes
Gastric cavity
pore
pores
spicule
flagellum

6. Circulation Water and nutrients entre through pores
Water and wastes exit through the osculum (giant hole)
oscule
Gastric cavity
pore

7. Movement Sessile: adults always attached to a surface
Ciliated larva swim to find a new place to settle

8. ***Digestion INTRACELLULAR***
choanocyte
amibocytes
Feeding
Filtration
Choanocytes beat their flagella to create a flow of water that brings suspended food particles to the interieur of the sponge
The particles are transported to the amoebocytes, the site of digestion
The amoebocytes wander and deliver the digested nutrients to the other parts of the sponge
***Digestion INTRACELLULAR***

9. Respiration The Nervous System
Oxygen is obtained and carbon dioxide released through diffusion between the cells and water
Each cell is in contact with water
The Nervous System
none

10. Defense
Sponges produce numerous chemical compounds (toxic) that gives them a bad tast and can stop other organisms from growing on or near them (competition)

11. Reproduction Asexual: through budding
Sexual: hermaphrodites (each individual produces male and female gametes but they never self-fertilize)
The sperm are released into the water where they fertilize the eggs in another sponge
The zygote develops into a cilliated larva that swims away (or carried by water currents) before it settles down and grows into a new sponge
Regeneratoin: seperated sponge cells can regroup together to form a new sponge

13. Ecological and Economical Importance
Filtre water
Important source of noutrition for snails, sea stars and fish
Homes for little invertebrates
Used by artists
Chemicals used for anitbiotics

16. Phylum Cnidaria (jellies, sea anemones & corals)

18. Appearance Radial Symmetry 2 layers of cell tissues: 2 formes:
a) ectoderme: the outer layers of cells (epidermis)
b) endoderme: lines the gastrovascular cavity (gastrodermis)
Mesoglea lies between the 2 layers
2 formes:
a) polyp: sessile, tubular, tentacles surround opening
b) medusa: free-swimming, bell shaped with tentacles

19. Structure Gastric cavity mouth tentacle Gastric cavity mouth tentacle
a) polyp
b) medusa

20. Circulation
Water, nutrients and waste all enter or leave through the mouth ** (not very sanitary)
Cnidarians have a ‘mouth/anus’
This is why you don’t stick your finger in the middle of a sea anemone.

21. Movement
Epidermis cells contract which allows them to expand or shrink
Do not possess true muscle cells
Polyp: contract and dialate the body and tentacles (body waves)
Medusa: contracts the ‘bell’ forcing water out of the shell – moves via jet propulsion

22. Feeding
Nematocysts: stinging organelles located on the cnidarians surface, a tiny capsule containing a filament covered with tiny spines that and injects poison that can cause paralysis
Nematocysts found on tentacles, capture prey and bring in towards the mouth
Food is digested by enzymes secreated in the gastrovascular cavity
***digestion EXTRACELLULAR***

24. The Nematocysts Cnidocil Filament Nematocyst Barb Cnidocyte
URL: Searched 09/12/06

25. Respiration The Nervous System
Oxygen is acquired and carbon dioxide release through diffusion between the cells and water
Every cell touches water
The Nervous System
Very primitive nerve net

26. Defense Uses nematocyst as a means of defense
Corals have an exoskeleton made of calcium carbonate

27. Reproduction
Typically, cnidarians have a sexual phase (medusa) and an asexual phase (polyp)
Asexual: through budding and regeneration
Sexual: medusa males or females release gametes into the water ***(external fertilization)***

28. Ecological and Economical Importance
Food and shelter for other organisms
Coral reefs protect the coast from the effects of waves
Coral reefs have economic value as tourist attractions
Very vulnerable to pollutants

29. Photos