1. Phylum Porifera - Sponges
General characteristics:
Porifera means “Pore Bearer”
Body multi-cellular but has no tissue.
Sponge skeleton made up of spongin, modified form of collagen, which gives it is flexibility.
Also contains spicules, needle-shaped structures made of silica, to give support to body and used as a defense mechanism.
Asymmetric body plan
Can be commercially raised
Habitat: marine environment

2. Phylum Porifera - Sponges
Nutrition: filter feeders where water moves through the body and microscopic food particles are sifted from the water by specialized cells called choanocytes, also known as collar cells that collect food and start digestion, and amoebocytes, cells that transport the digested food to other cells.

3. Phylum Porifera - Sponges
Digestion: Intracellular, takes place inside cells
Circulation: takes place through diffusion when water enters the body through an incurrent pore
Respiration: diffusion of oxygen and carbon dioxide using specialized cells takes place when water enters the body through an outer pore
Excretion: diffusion of wastes including: ammonia, and carbon dioxide and into the water and is released through an excurrent pore or osculum.

4. Phylum Porifera - Sponges
Nervous: Sponges have no nerve cells. They protect themselves by producing foul smelling toxins or releasing spicules.
Toxic sponge Biemna hartmani, whose mucus produces severe burning sensation on contact with skin

5. Phylum Porifera - Sponges
Reproduction:
Sexual: Sponges are hermaphrodites meaning that they contain both male and female sexual organs.
Natural hermaphrodites typically have systems in place to prevent self fertilization.
Internal Fertilization-occurs when eggs and sperm are released into a central cavity; the zygote develops into a ciliated larve.

6. Phylum Porifera - Sponges
Asexual: Occurs through budding, fragmentation (sponges are chopped up and each piece can start a complete sponge, or the creation of gemmules (dormant specialized sponge cells)

7. Phylum Porifera - Sponges
Mobility: larva are motile (can move) but adults are sessile, (live attached to something as an adult).

8. Phylum Cnidaria General Characteristics:
Cnidarian means “stinging creature.”
Radial symmetry
Two different body plans exist:
Medusa- bell shaped and mouth is directed downward and polyp-vase shaped and mouth is directed upward.
Cnidarians are made up of two tissue layers separated by mesoglea.
Have a hydrostatic skeleton
Habitat: aquatic

9. Polyps and Medusa

10. Phylum Cnidaria
Nutrition: Capture pray using cnidocytes (stinging cells).
Contain a nematocyst-fluid filled capsule which contains a long spirally, coiled hollow thread.
When the trigger of the cnidocyte is touched, the nematocyst is discharged and can either just trap prey or penetrate and inject toxins to Sting prey and paralyze it so that it can be pulled into the mouth to be digested.
Some organisms become immune to the sting and form mutualistic relationships with cnidarians.

11. How do jellyfish sting?

12. Alarm Jellyfish
ube.com/watch? v=CG7Cf2EgJq 4

13. Phylum Cnidaria
Digestion: takes place in the gastrovascular cavity, a digestive chamber with one opening, food enters here.
Break down occurs in the cavity and then partially digested food is absorbed by the gastroderm and digestion is finished intracellularly.

14. Phylum Cnidaria
Circulation: takes place through diffusion in the gastrovascular cavity
Respiration: Diffusion of oxygen and carbon dioxide takes place in the gastrovascular cavity.
Excretion: diffusion through the body wall or exits out through the mouth of the organism.

15. Phylum Cnidaria Nervous:
Touch sensitive stinging cells called nematocysts
a nerve net, allows transmission of impulses in several directions at once, but no brain
statocysts used to detect gravity
ocelli to detect light (eyespots)

16. Phylum Cnidaria Reproduction:
Asexual reproduction can occur through budding and fission.

17. Phylum Cnidaria Reproduction:
Sexual reproduction occurs through external fertilization when the sperm is united with an egg outside of the body

18. Phylum Cnidaria
Examples: sea anemones and coral have a dominant polyp stage, hydra alternate between forms, jellyfish and sea wasps (box jelly) with a dominant medusa form

19. Examples: Sea anemones-share a symbiotic relationship with clown fish
Coral-responsible for building coral reefs by the slow accumulation of limestone (from their calcium carbonate skeleton)
Portuguese Man O’ War- colonial organism made up of individual organism called zooids that function together as one large organism.