1. Phylum Porifera & Phylum Cnidaria
Learning Outcome G2
Phylum Porifera & Phylum Cnidaria

2. Learning Outcome G2
Analyse the increasing complexity of the Phylum Porifera and the Phylum Cnidaria

3. Student Achievement Indicators
Students who have fully met this learning outcome will be able to:
Examine members of the Phylum Porifera and identify their unifying characteristics
Describe how poriferans carry out their life functions
Examine members of the Phylum Cnidaria and identify their unifying characteristics
Describe how cnidarians carry out their life functions
Compare polyp and medusa with respect to structure, general function, and motility
Suggest the advantages of a motile form in the life cycle of a cnidarian
Explain the evolutionary significance of colonial (poriferan) versus multicellular (cnidarian) life forms
Describe the ecological roles of sponges and cnidarians

4. Phylum Porifera – The Sponges

5. Classification
Kingdom Animalia
Phylum Porifera

6. Characteristics An invertebrate Sessile (do not move)
Found in oceans and lakes
Have specialized cells but these cells are not arranged into organs or tissues
No nervous system or brain
No muscle tissue, which means sponges are not capable of any type of movement

7. Characteristics Highly successful group; 500 million years old
An evolutionary dead end, because no other groups have developed from the sponges
Spicules make up the internal skeleton of the sponges
Amebocytes are specialized cells that build spicules from calcium carbonate (CaCO3) or silicon dioxide (SiO2).
No body symmetry

11. Feeding
Filter feeder
Collar cells with flagellum create water currents that brings water into and out of the cells
Water and food enter the sponge through small pores and exit via the osculum
Digestion occurs in the collar cells or amebocytes that wander around the middle layer of the sponge

13. Reproduction Sexual Reproduction
Generally hermaphroditic (produce both male and female gametes)
Have a motile larvae stage
An egg (n) is fertilized by a sperm (n) and develops into a free-swimming larvae (2n).
Larve attaches to bottom undergoes metamorphosis
After metamorphosis an adults sponge develops (2n)

15. Reproduction Asexual Reproduction Budding or branching
Produces gemmules under unfavorable conditions
Gemmules are sphere-shaped collections of amebocytes surrounded by a tough layer of spicules.
These gemmules can survive long periods of freezing temperatures and droughts, which would kill an adult sponge.
When conditions become favorable again these gemmules will develop into a new adult sponge.

17. Ecological Roles Shelter for invertebrates
Preyed on by bacteria, algae and other microscopic organisms
Form symbiotic relationships with photosynthetic organisms.
In this relationship the photosynthetic organisms provide food and oxygen.
The role of the sponge is to remove waste
Specialized amebocytes called “boring sponges” are vital in marine habitats because they clear the ocean floor

18. Protection
Produce toxins and antibiotics that are used to deter bacteria and algal predators

19. Human Uses
Caribbean sponge has a compound that may be useful in fighting leukemia and herpes

20. Phylum Cnidaria

21. Classification Kingdom Animalia Phylum Cnidaria
Class: Cubozoa (sea wasps or box jellyfish)
Class: Scyphozoa (jellyfishes)
Class: Anthozoa (anemones and corals)
Class: Hydrozoa (hydra)

22. Class Cubozoa

23. Class Scyphozoa

24. Class Anthozoa

25. Class Hydrozoa

26. Characteristics Invertebrate Radial symmetry
Have true tissue, which allows specialization
Only have two germ layers: ectoderm and endoderm
Middle layer is not a mesoderm, but a layer composed of a jelly-like substance called mesoglea.
This group includes jellyfish, hydra, sea anemone and reef coral
Aquatic organisms
Generally marine, but there are fresh water species such as hydra
A nerve net encircles the body
Some free swimming species have a ring of nerve cells around the bell (perhaps a primitive beginning of a central nervous system)
Have coordination of nerves and muscles

27. Hydra

29. Feeding
Capture food using specialized cells within the tentacles called cnidocysts, which contains small sacs called nematocysts.
Nematocysts contain coiled, hollow tubes that shoot out rapidly and penetrates the skin of the prey
These nematocysts may contain toxins that paralyze the prey
Capture food and digest it in a sac-like cavity that has a single opening
Waste is expelled from the same opening
This opening is controlled by muscle, which allows cnidarians to engulf larger prey

32. Reproduction Alternation of generations lifecycle
Two body forms: polyp and medusa
Polyp
Has a sessile tube-like body within the oral end directed upwards
Vental end is attached to the ocean/lake floor
Example – hydra

33. Reproduction Medusa Bell-shaped organism
Mouth is located on the underside
Have a thick middle layer called the mesoglea
Cnidarians are often known as jellyfish due to their medusa state, although some species only have a polyp stage

35. Sexual Reproduction
Egg/sperm arise from gastrodermal cells that have migrated to specific locations in the epidermis of the polyp or on the underside of the medusa
Egg/sperm are released into the water and undergo external fertilization
Zygote develops into a free-swimming ciliated larva called a planula
Planula has an elongated body shape, is radially symmetrically, and has no gastrovascular cavity or mouth

36. Sexual Reproduction
Planula attaches to substrate and develops into a hydroid colony (polyp stage)
Some hydroid colonies do not produce a free swimming medusa stage
Example – hydra
Hydroid colonies exhibit specialization
These colonies are used to facilitate feeding and reproduction
These colonies are also used as a defense mechanisms.

38. Reproduction in Hydra Hydra may reproduce asexually
Budding outgrowth of body walls
Regeneration similar to sponges
Hydra also reproduce sexually during unfavorable conditions
May be hermaphroditic or have separate sexes
After fertilization zygote divides and becomes an embryo that is enclosed in a protective case.
This encased embryo is called a cyst, and it drops of the parent and lies dormant until favorable conditions usually to spring.

39. Protection Used the same mechanisms as in feeding
Specialized cells within the tentacle called cnidocytes that can expel a poison that can be used to deter predators.

40. Ecological Roles
Involved in symbiotic relationships with many organisms
Example - sea anemone and fish, shrimp and small animals. These small organisms live among the tentacles of the very large sea anemone. The sea anemone protects the symbiont and provides food. In return the sea anemone is cleaned and protected by these symbionts from potential predators.
Also Provide habitats for many small invertebrates and microorganisms
Example - coral reefs

41. Human Uses
Protect coasts areas from damage caused by storms and large waves.
These reefs are being damaged by pollution
Once damaged the calcium carbonate skeleton of these reefs break apart and no longer offer protection to our coastal areas
Coral is used to make beautiful jewelry and decorative articles
Corals produce certain chemical for their defense
Some of these chemicals can be used to manufacture drugs against cancer, and some toxins produced by corals are used by scientists to study and understand the function of nerve cells.