1. Poriferans

2. Phylum Porifera Phylum Porifera – “pore-bearers” Sponges
Tiny openings, pores, all over the body
Cambrian Period – 540 m.y.a.; oldest and simplest animals
Adults are sessile – attached to a single spot
Heterotrophic, multicellular, no cell walls, few specialized cells
No mouth or gut, no tissues, no organ systems
Evolutionary dead end

3. Form and Function of Sponges
Movement of water through sponge provides for feeding, respiration, circulation, and excretion
Body plan
Asymmetrical “water pump” – body forms wall around central cavity, where water is continuously pumped
Choanocytes (aka Collar Cells) – create currents with flagella
Most have an osculum – large exit hole at top of sponge

4. Form and Function of Sponges (continued)
Simple skeletons
Spicules – sponge “bones” made of calcium carbonate (CaCO3) or silica (SiO2) – these are in hard sponges
Archaeocytes – make spicules
Softer sponges have skeletons made of spongin – these are used as natural bath sponges

5. Sponge Anatomy Water flow Osculum Choanocyte Central cavity Pores
Spicule
Pore cell
Pore
Epidermal cell
Archaeocyte

6. Feeding in Sponges
Filter feeders – sift microscopic food particles from water
Digestion is intracellular
Food particles engulfed by choanocytes lining body cavity by endocytosis
Food may be digested or passed on to archaeocytes
Archaeocytes digest food and wander around to other cells delivering nutrients

7. Respiration, Circulation, and Excretion in Sponges
Rely on movement of water through bodies to provide simple mechanism for respiration, circulation, and excretion
Diffusion is important for sponges

8. Response in Sponges
No nervous system, but can produce toxins

9. Reproduction in Sponges
Sexually or asexually
Sexual – most sponges have eggs and sperm in one sponge
Eggs held in body wall
Sperm released into water
Eggs and sperm produced at different times within sponge
Sperm absorbed by archaeocytes and carried to eggs
Fertilized eggs forms zygote which develops into larvae, which are planktonic and motile. Eventually, larvae settle down to bottom and grow into a new sponge.

10. Sponge Life Cycle
MEIOSIS
Haploid (N)
Diploid (2N)
Sperm from a sponge are released into the surrounding water. Water currents carry the sperm to other sponges.
New sponge
Sperm (N)
Mature sponge (2N)
Egg (N)
Swimming larva
Larva (2N)
The zygote develops into a free-swimming larva. Water currents carry the larva until it attaches to a surface and grows into a new sponge.
Sperm enter another sponge through pores. The sperm are carried to eggs inside the body wall. Sperm fertilize eggs.
FERTILIZATION

11. Reproduction in Sponges (continued)
Asexual
Gemmules – collections of archaeocytes surrounded by spicules that can survive freezing and heat
Conditions favorable, gemmule grows into new sponge
Budding – part of sponge breaks off, settles, grows into new sponge

12. Ecology of Sponges
Form sponge “habitats” for worms, shrimps, snails, and starfish
Symbionts with bacteria, blue-green bacteria, or plant-like protists
Natural bath sponges
Provide toxins that fight bacteria, viruses, leukemia, and herpes

13. Summary of Cell Specialization in Sponges
Choanocytes
Create water currents with flagella
Capture food
Archaeocytes
Make spicules
Deliver nutrients to sponge
Assist with reproduction

14. Examples of Sponges

15. Cnidarians

16. Cnidarians Phylum Cnidaria – cnidocytes – stinging cells
Jellyfish, sea anemone, coral
Soft-bodied, carnivorous animals with stinging tentacles arranged around their mouth
Simplest animals to have body symmetry and specialized tissues
Within each cnidocyte is a nematocyst (poison-filled stinging structure used for food capture and protection)

17. Form and Function of Cnidarians
Only a few cells thick and simple body systems
Body plan
Radial symmetry with 2 possible body forms:
Polyp – sessile and flower-like
Medusa – motile and bell-shaped
Three layers of cells
Gastroderm – inner lining of gastrovascular cavity - digestion
Mesoglea – middle layer – can be a thin or thick layer
Epidermis – outer layer

18. Body Forms of Cnidarians
Epidermis
Mesoglea
Gastroderm
Tentacles
Mouth/anus
Gastrovascular cavity
Mesoglea
Gastrovascular cavity
Mouth/anus
Tentacles
Medusa
Polyp

19. Feeding in Cnidarians
Nematocysts – located on tentacles; tiny spring-loaded harpoons
Food pushed into mouth by tentacles
Food digested and absorbed by diffusion

20. Respiration, Circulation, and Excretion in Cnidarians
Respiration and wastes eliminated by diffusion through body wall
No organized internal transport network or excretory system

21. Response in Cnidarians
No organized central nervous system (CNS)
Simple nerve nets – loosely organized network of nerve cells allowing detection of stimuli
Statocysts – sensory cells for balance
Ocelli – eyespots detect light

22. Movement in Cnidarians
Hydrostatic skeleton – layer of longitudinal muscles, together with the water in the gastrovascular cavity, allow movement
Epidermal cells act as muscles

23. Reproduction in Cnidarians
Sexual and asexual
Asexual – polyps reproduce by budding
Sexual – external fertilization in the water
Asexual Reproduction
Sexual Reproduction

24. Groups of Cnidarians
Includes hydras and their relatives, jellyfishes, sea anemones, and corals

25. Class Hydrozoa – Hydras and Other Relatives
Long polyp stage
Short medusa stage
Hydra – fresh-water – no medusa
Portuguese Man-O-War – floating colony contains specialized polyps; one polyp is enlarged and full of air to keep the animal afloat, the other polyps are for feeding and reproduction

26. Examples of Hydrozoans
Colonial Hydrozoan
Portuguese Man-O-War
Green Hydra

27. Class Scyphozoa – Jellyfish
Same life-cycle as hydrozoans
Medusa – long-lived
Lion’s Mane
Reproduce sexually
Some very toxic and even deadly

28. Examples of Scyphozoans

29. Class Anthozoa – Sea Anemones and Corals
Only polyp life stage
Colonial
Sexual and asexual reproduction
Corals – reef builders and symbionts with photosynthetic algae
Skeleton of calcium carbonate (CaCO3)
Colony grows slowly and lives for thousands of years

30. Examples of Anthozoans

31. Ecology of Corals Great Barrier Reef – 2,000km long, 80 km wide
Sea anemone and clown fish – mutualism
Coral – habitat for many animals
Protect land from wave action
Building blocks
Jewelry
Anti-cancer drugs
In danger due to human activity