1. Sponges and Cnidarians

2. Sponges
Phylum Porifera
“Pore bearing”

4. Defining Characteristics
sessile – remain attached to single place as adults.
No mouth or gut, no muscles, no nervous system.
No tissues or organ systems. Collection of specialized cells.
Could run through a blender, cells would re-assemble to make new sponge.

6. Body Plan osculum Body Plan choanocyte Epidermal cell Archaeocyte or
amoebocyte
pore
spicule

7. Spicules

8. Feeding: How do sponges get food and digest it?
Filter feeders. Flagella (tails) whip around, making currents that draw water in through pores.
Archaeocytes pick up and digest bits of dead animal and plant material (detritis) from incoming water.

9. Respiration: How do sponges exchange oxygen and carbon dioxide?
Oxygen in water diffuses into cells, carbon dioxide in cells diffuses out into water.
Diffusion = movement of molecules from area of high concentration to low

10. Nutrients carried by archaeocytes.
Circulation: How do sponges transport oxygen, carbon dioxide, and nutrients to wherever they are needed?
Oxygen and carbon dioxide carried by diffusion and water currents created by flagella.
Nutrients carried by archaeocytes.

11. Excretion: How do sponges get rid of waste products?
Passes from cells into central cavity, carried out osculum (opening at top) by water currents.

12. Response: What kind of nervous system do sponges have?
No brain, no nervous system, no senses
Very basic response, all “automatic”

13. Asexually by budding. A piece of sponge breaks off and grows into
REPRODUCTION
Asexually by budding. A piece of
sponge breaks off and grows into
new sponge.

14. Asexually by budding. A piece of sponge breaks off and grows into
REPRODUCTION
Asexually by budding. A piece of
sponge breaks off and grows into
new sponge.
Sexually. Sponges makes both
sperm and eggs. Sperm released
into water, where taken in by
another sponge. Sperm fertilizes
egg inside sponge. Larvae grow
and are carried away by water
currents.

15. Mutualism = relationship where both benefit.
Ecology: How are sponges interconnected and interdependent on their environment?
Sponges contain photosynthetic bacteria and algae, which provide food and oxygen for sponge. Sponge provides shelter.
Mutualism = relationship where both benefit.
Sponges provide shelter for snails, shrimp, sea stars, and other small sea animals.

16. corals
jellyfish
Cnidarians
hydra
Sea anemone
Sea pens

17. Jellyfish, sea anemones, coral, hydra, sea pens
Defining characteristics: What animals are classified as cnidarians? What do they have in common?
Jellyfish, sea anemones, coral, hydra, sea pens
Soft bodied and carnivorous
Have tentacles with stinging cells (nematocysts)

18. Cnidarian Body Plan Radial symmetry
Central mouth surrounded by tentacles
Body wall surrounds gastrovascular cavity (digestive chamber)
2-way digestive tract: Food and waste go through same opening.

19. Nematocysts: Stinging Cells

21. Feeding: How do cnidarians get food and digest it?
Use nematocysts to sting and paralyze prey.
Tentacles pull prey into mouth. Digested in gastrovascular cavity.

22. Respiration: How do cnidarians exchange oxygen and carbon dioxide?
Diffusion between cells and water outside and in gastrovascular cavity.
No cells more than a few centimeters away from water.

23. How does diffusion work?
Oxygen in water diffuses into cells, carbon dioxide in cells diffuses out into water.
Diffusion = movement of molecules from area of high concentration to low

24. Diffusion through water in and out of cells.
Circulation: How do cnidarians transport oxygen, carbon dioxide, and nutrients to wherever they are needed?
Diffusion through water in and out of cells.

25. Excretion: How do cnidarians get rid of waste products?
Diffusion through cell walls into gastrovascular cavity, then out mouth/anus into surrounding water.

26. Response: What kind of nervous system do cnidarians have?
No brain; only a network of interconnected nerve cells (nerve net)
Also have eyespots and other sensory cells.

27. Reproduction: How do cnidarians reproduce?
Stage 1: Medusa is motile (can move around). Reproduces sexually. Males and females release sperm and egg into water. Fertilization happens in water.
Stage 2: Fertilized egg grows into larva, which turns into polyp.
Stage 3: Polyp is sessile (stays in one place like plant). Reproduces asexually by budding.

28. Ecology: How are cnidarians interconnected and interdependent on their environment? How are coral reef ecosystems endangered?
Most corals contain photosynthetic algae that provide food for coral. Coral provides shelter for algae.
Coral reefs endangered by human activity: divers, sediment from industry and farming, overfishing.
Global warming may also be causing ocean temperatures to rise, killing the algae inside corals. This causes bleaching; they turn pale and die.

29. Coral Bleaching

30. Coral Reefs with Severe Bleaching

31. Why are coral reefs important?
Among oldest and most diverse of Earth’s ecosystems. “Rainforests of the sea”
Breeding ground for many fish and other marine life.
Food, jobs for millions of people. Billions of dollars each year from tourism.
Protect shorelines from waves, storms, floods.

34. Videos Sponges http://www.youtube.com/watch?v=laJgUrSsO_k Sea pens
Giant jellyfish

35. Questions?