1. Sponges, Jellyfish, flatworm, roundworms
Simple invertebrates
Sponges, Jellyfish, flatworm, roundworms

2. Sponges Simplest animal – early naturalist classified them as plants
Lack symmetry (asymmetrical)
Specialized cells embedded in a gel-like mesohyl (like chopped fruit in gelatin)
No tissue organs
Do have cell recognition
Sessile – attached to rock or coral reef
1cm to 2m

3. Sponge in the wild

4. Sponge structure
Have tiny opening / pores called ostia where water enters in (lending the name porifera -p)
Large oscula through which water exists
Choanocytes (collar cells)- flagellated cells that beat causing water to come in. Small hairlike projections on the collar trap tiny organisms
Amoebocytes in the mesophyl pick up nutrients released by collar cells. They carry the nutrients around.
Ancient choanoflagellates are though to be sponge ancestors

5. Picture of structure

6. Sponge diversity Sponges grouped based on composition of skeleton
Calcareous sponges – have spicule (tiny needle) composed of calcium carbonate
Glass sponge – spicule made of silica
Demosponges – made of both silica and spongin (flexible protein fiber)
(luffa sponge is really a gourd)

7. Phylogenic relationship

8. Sponge reproduction
Asexually – regenerate when cut into pieces. Fragments, Budding, Gemmules – clusters of amoebocytes encased in protective coat during harsh conditions
Sexual – Hermaphrodite but production of eggs and sperm at different times (no self-fertilization)
Collar cells pass the sperm into the mesohyl where egg cells live
Brief free – swimming larvae stage

9. Sponge reproduction

10. Cnidarians -p Jellyfish, sea anemones, hydras, corals Radial symmetry
Medusa – free-floating, jellylike, umbrella
Polyp – tubelike, attached to rock, tenticles around the mouth
Some only medusas, only polyp, both
2 layers of cells – ectoderm (outiside) and endoderm (inside) with middle mesoglea gel

11. Jellyfish parts

12. Cnidarian structure
Gastrovacular cavity – with tentacles surrounding. Cnidocytes (stinging cells) with nematocyste (barbed harpoon cells), used to stun prey or for defense
Enzymes break food down into small particles and lining cells engulf particles and digestion is completed intracellularly.

13. Anatomy of a jellyfish

14. Hydrozoans – c
Hydra – g: freshwater, no medusa stage, basal disk that attach, glide on secretion, move by tumbling, white or brown unless algae living (green)
Marine – Portuguese man of war (physalia - g) both medusa and polyps. Gas filled float allow to and can have tenticles 60 m (197 ft), neurotoxins can kill humans.

15. Hydra picture

16. Reproduction Asexually – budding
Obelia – g: colonies when polyp asexually reproduce but not separates.
Sexual – medusa release sperm / egg, produce free – swimming larvae called planulae

17. Cnidarian reproduction

18. Scyphozoans – c
True jellyfish, cup animal (skyphos, zoia), thimble to queen-size mattress
Aurelia - g (stinging nettle) – most familiar – Tiny polyp on rocky surface, medusa released. Most of life as a medusa
Cubozoans (box jellies), cube- shaped medusa, little to no polyp stage, few cm to 25 cm. Sea wasp – northern coast of Australia.
Ctenophora – p: comb jellies, only have a medusa and no cnidocytes, sticky substance on tentacles

19. Box jelly – comb jelly

20. Anthozoans –c
Larges class – only polyps, sea anemone and corals, sea pansies, sea fans, sea whips
Stalklike body with tentacles in groups of six
Dinoflagellates (symbiotic algae), live in for protects, provides some food for polyps. Causes the brillant colors of the animals
Asexual – buds
Sexual – egg/ sperm resultant planulae

21. Specific Anthrozoans
Sea Anemone, small, feed on fish, highly muscular and relatively complex. React to touch – retract their tentacles in and form a ball. Asexual – pulls themselves into 2 halves
Corals – live in colonies called reefs, secret tough, stone like calcium carbonate (soft corals – no secretion). Top layer of a reef contain living coral, skeleton remains when die for protection of the reef.

22. Sea anemone

23. Coral Reef
Diversity of life rivals the tropical rain forest, as many at 3,00 species of animal in a single reef
Algae, mollusk shells – help form hard reef. Found in less than 100 m deep for the algae to be photosynthetic
Small animals find protection
Protect coastlines from erosion
Tourist and research for medicines
Human activity threatens, including pollution

24. Reef: below and above

25. Flatworms Platyhelminthes – p Largest group of acoelomate worms
Have a middle tissue layer (mesoderm) and organized into organs
Bilaterally symmetrical, flat – dissolved substances to pass through by diffusion (no respiratory or circulatory system)
Highly branched gastrovascular cavity

26. Planarian anatomy picture

27. Flatworm classes
Turbellaria – c : free – living marine, difficult to raise in captivity, Freshwater Dugesia – g (planarian) usually studied
Cestodia -c: parasitic, Tapeworms, hooklike / sucker structures, digest food, rectangular body sections called proglottids (complete reproductive unit – easily spread – 12 m)
Trematoda - c: Flukes (parasite), Endoparasite – inside host, Ectoparasite – outside host, get food directly from host. Blood fluke – Schistosoma -g: larvae bore into intestinal wall causing bleeding and Liver damage

28. Flatworm classes picture

29. Flatworm reproduction

30. Roundworms / Nematoda Common canine parasite, 50 plant / animal
Pseudocoelom – act as simple circulatory and gas exchange, one way digestion (mouth to anus),
Ascaries lumbricoides –s: soil, larvae – bore blood vessels and enter blood stream
Trichinella spiralis –s: infected, undercooked, pork (pig)
Nector -g (hookworm) – tropics soil, larvae penetrate soles of the feet.

31. Nematoda reproduction

32. Roundworm picture