1. UNIT 6 INVERTEBRATES PART 1
SPONGES; CNIDARIANS; CTENOPHORES; PLATYHELMINTHES; NEMERTEA; NEMATODA; ANNELIDA; SIPUNCLA; ECHIURANS; MOLLUCS;

2. The following is a website that I found of photographs, videos, and species identification of organisms around Australia.

3. Animals classified into two main groups:
Vertebrates: those having backbones
Invertebrates: those that do not have a backbone (97% of all animal species)
Most marine or aquatic except for the insects

4. SPONGES (Phylum Porifera)
Most simple multicellular animal
Organized on the cellular level- no true tissues or organs; the cells are independent of each other
Almost all marine
All are sessile (permanently attached to a surface)
video

5. Suspension feeder- eat food particles suspended in water
Filter feeder- filter food particles

6. The basic body form of all sponges is a sac-like structure consisting of three layers –
an outer layer of epidermal cells
an inner layer of cells, many of which are flagellated cells called choanocytes
a middle layer of amoeboid cells that form skeletal structures of various sorts. These layers are perforated by a large number of small pores (thus the name Porifera). The cavity of this sac is called the spongocoel and has at least one opening to the outside, called an osculum

7. The skeletons of sponges can be composed of an organic substance called spongin (the stuff of an ordinary bath sponge), or they may have calcareous or siliceous skeletons composed of chambers, or more commonly rod-like branched elements called spicules. After death, spicules are scattered across the sea floor and may be found as disarticulated microfossils.
link

9. The poriferans (sponges) are characterized by cell groups that are independent of each other and have the ability to change their function during their life cycle.
The skeletons of sponges can be composed of an organic substance called spongin (the stuff of an ordinary bath sponge), or they may have calcareous or siliceous skeletons composed of chambers, or more commonly rod-like branched elements called spicules.
After death, spicules are scattered across the sea floor and may be found as disarticulated microfossils.

10. 3 basic types of sponges
The Asconoid Sponges example: Leucoselenia (Class Calcispongiae)

11. Asconoid sponges have the simplest organization
Asconoid sponges have the simplest organization. Choanocytes line the spongocoel, drawing water through small ostia and expelling it through the osculum.

12. The Syconoid Sponges example: Scypha (Class Calcispongiae)

13. Syconoid sponges have a tubular design similar to the ascon sponge, but the body wall is folded. The "folds" form radial canals. Choanocytes line the radial canals rather than the spongocoel.

14. This shows the radial canals

16. The Leuconoid Sponges example: the "bath sponge" (Class Demospongiae) .

17. Leuconoid sponges represent the most complex body form.
The canal system is extensively branched. Small incurrent canals lead to flagellated chambers lined by choanocytes. Flagellated chambers discharge water into excurrent canals that eventually lead to an osculum.
Usually there are many oscula in each sponge.
The skeleton of this sponge is made of a soft protein, called spongin, rather than calcium carbonate or silica
Link to sponge photos

18. REPRODUCTION ASEXUAL: branches or buds break off
SEXUALLY: produce gametes in specialized collar cells or amebocytes
MOST HERMAPHRODITIC
BROADCAST SPAWNING- release of sperm into the water; eggs remain inside the body and fertilization is internal
Development inside sponge; a planktonic larva called a parenchymula larva
metamorphosis

19. CNIDARIANS
video

20. Basic characteristics
Tissues evolved to perform certain functions
Also called coelenterates
Ex: sea anemones, jellyfishes, coral
Radial symmetry (similar body parts arranged and repeated around a central axis)
Looks the same from all sides; no head, front or back
Oral surface = where mouth is
Aboral surface = side without mouth

21. Basic characteristics cont.
Centrally located mouth surrounded by tentacles that capture and handle food
Mouth opens into a gut where food is digested
Have nematocysts (or cnidae) that are specialized cells that discharge poison to help maintain food
Feeding and digestion: carnivores; initial phase of digestion is said to be extracellular because it takes place outside cells; intracellular digestion within cells lining the gut complete the food breakdown

23. Medusaes have a statocysts that give them a sense of balance
Behavior- have specialized nerve cells which interconnect to form a nerve net that transmits impulses in all directions
Medusaes have a statocysts that give them a sense of balance
Small calcareous bodies in fluid-filled chambers with small hairs

24. 2 basic forms 1. Polyp= sac-like life stage with mouth and tentacles
2. Medusa= bell-like; jellyfish; upside down polyp
Some animals exhibit both stages in their life; others exhibit only 1 kind throughout their life
Larvae = planula- a cylindrical ciliated stage made of two cell layers; planktonic until it settles on the bottom

25. Cell layers of Cnidaria
2 layers form the body wall
Epidermis- external
Gastrodermis- lines the gut
Mesoglea- narrow; gelatinous middle layer that contains no cells
In a medusa, the layer is expanded to form a gelatinous, domed bell

26. CLASSES OF CNIDARIANS 10,000 known species
1. Hydrozoans- wide range of forms
A. Siphonophores- form drifting colonies of polyps
Ex: Portuguese man-of-war; some of the colony are specialized as floats
Some contain droplets of oil
Some form long tentacles to capture prey
Reproduction- varies; some have specific reproductive polyps that release gametes and fertilization takes place and develops into swimming planulae that settles on the bottom and develops into a polyp which divides into interconnected polyps

27. Marrus orthocanna, a deep sea siphonophore
Marrus orthocanna, a deep sea siphonophore. The combined digestive and circulatory system is red; all other parts are transparent.

28. Physophora hydrostatica
Man-o-war

29. image48.webshots.com/.../ ljKMfl_ph.jpg
Most Hydrozoans are feathery or bushy colonies of tiny polyps.

30. 2. Scyphozoans- larger jellyfish
Large medusa dominant life stage
Reproduction: polyps are small; release juvenile medusas
Some bell’s may reach a diameter of 2 m; a just discovered one that is 3 m
Swim w/a rhythmic contraction of the bell; easily carried by currents
Can be very dangerous; fatal stings

32. Aurelia aurita (moon jelly)

33. 3. Cubozoa- most toxic Ex: sea wasp- box jellyfish
Death due to heart failure
There is an antivenom

34. The box jellyfish,  or sea wasp (Chironex) that swims in tropical waters off the coast of Australia with a width of approximately 25 cm can kill a person within minutes! 
bioweb.uwlax.edu/.../Lab_3a-07a.jpg

35. Carybdea

36. 4. Anthozoans- solitary or colonial polyps that lack a medusa
Largest number of Cnidarian species
More complex body
Gut has several thin partitions called septa that increase the surface area for digestion and provide support allowing the polyp to be larger
Ex: sea anemones; corals

38. CORALS-
HERMATYPIC- corals where the polyps produce calcium carbonate skeletons; form reefs
AHERMATYPIC- corals who do not help to build reefs
Scleractinian corals- most important reef builders; also known as stony or “true” corals
Contain symbiotic zooanthellae (dinoflagellates) that help the corals make their calcium carbonate skeletons

39. The coral polyp
Reefs are colony of polyps connected with a thin layer of tissue
Starts when a planktonic coral larva, called a planula, settles on a hard surface and metamorphoses into a polyp which divides over and over to produce the colony
Digestive systems remain connected and share a common nervous system
Only living tissue is a thin layer on the surface

40. Hard Corals limestone skeletons multiple tentacles
Soft Corals soft skeleton with spicules 8 tentacles chemical repellents

41. Gorgonians- sea fans; colonial anthozoans
Precious corals and black corals are made into jewelry