1. Sponges and Cnidarians
Biology 112

2. Sponges Phylum Porifera Multicellular and heterotrophic
No cell wall and few specialized cells
Live their entire life attached to a surface
They eat by sifting microscopic food in water
Choanocytes are specialized structures that help move water through their body cavity
Water enters through pores and leaves through the osculum (a large hole at the top of the cavity)

3. Getting Everything it Needs
Digestion is intracellular
Takes place inside the cells
Not only is food provided using this sifting action but also everything for respiration, circulation and excretion

4. Sponges and Reproduction
Reproduce sexually and asexually
Sexually
Eggs are fertilized internally
Zygote develops into a larva
Larva is the immature stage of the organism that looks different from the adult
They are motile
Carried by the ocean to the floor and grow into an adult sponge
Asexually
By budding

5. cnidarians Phylum Cnidaria
Soft-bodied carnivores that have stinging tentacles arranged in circles around their mouth
Simplest animals that have body symmetry and specialized tissues
Exhibit radial symmetry
Central mouth with several tentacles

6. Two Distinct life stages
Polyp
Cylindrical body with arm-like tentacles and usually do not move
Lives attached to the surface with its mouth pointing upward
Medusa
Bell-shaped body with a mouth at the bottom
Free swimming

7. Cnidarians and digestion
Possess a gastrovascular cavity
Digestive chamber with one opening
Foods and wastes enter and leave this opening
Nutrients are transported throughout body by diffusion
Oxygen and wastes are diffused through the body walls

8. Cnidarians and response to stimuli
Gather information from their environment using specialized sensory cells
nerve nets
a network of nerve cells that together let cnidarians detect stimuli

9. Cnidarians and body structure
Possess a hydrostatic skeleton
Consists of layers of circular muscles as well as longitudinal muscles that, with the digestive cavity, allow it to move

10. Cnidarians and reproduction
Asexual – by budding
Sexual – external fertilization in water

11. Classification of cnidarians
Jellyfish
Live mostly as medusas
Hydras
Grow in branching colonies
Ex. Portuguese man-of-war
Sea Anemones and Corals
Only have a polyp stage
Colonial
Polyps grow together in large numbers
Secrete an underlying skeleton of calcium carbonate
Form coral reefs

12. Portuguese man-of-war

13. Coral reefs