1. Sponges and Cnidarians

2. SPONGES

3. Sponges Phylum Porifera
Have tiny openings, or pores, all over their bodies
Sessile: they live their entire life attached to a single spot
They are animals! Why…?

4. Sponges are Animals!!! Multicellular Heterotrophic No cell walls
Contain a few specialized cells

5. Form and Function in Sponges
Have nothing resembling a mouth or gut
Have no tissues or organ systems
Simple functions are carried out by a few specialized cells

6. Asymmetrical Have no front or back ends, no left and right sides
A large, cylindrical water pump
The body forms a wall around a large central cavity through which water flows continually

7. Feeding Filter feeders Sift microscopic food from the water
Particles are engulfed by choanocytes that line the body cavity

8. Respiration, Circulation, & Excretion
Rely on the movement of water through their bodies to carry out body functions
As water moves through the cavity:
Oxygen dissolved in the water diffuses into the surrounding cells
Carbon dioxide and other wastes, diffuse into the water and are carried away

9. Response No nervous system
Many sponges protect themselves by producing toxins that make them unpalatable or poisonous to potential predators

10. Reproduction Sexually or asexually
A single spore forms both eggs and sperm; usually at different times

11. Ecology of Sponges
Ideal habitats for marine animals such as snails, sea stars, sea cucumbers, and shrimp
Mutually beneficial relationships with bacteria, algae and plant-like protists
Many are green due to these organisms living in their tissues

12. Ecology of Sponges
Attached to the seafloor and may receive little sunlight
Some have spicules that look like cross-shaped antennae
Like a lens or magnifying glass, they focus and direct incoming sunlight

13. CNIDARIANS

14. Cnidarians Phylum Cnidaria Hydras, jellies, sea anemones, and corals
Soft-bodied
Carnivorous
Stinging tentacles arranged in circles around their mouths
Simplest animals to have body symmetry and specialized cells

15. Form and Function in Cnidarians
Only a few cells thick
Simple body systems
Most of their responses to the environment are carried out by specialized cells and tissues

16. Radially Symmetrical
Central mouth surrounded by numerous tentacles that extend outward from the body
Life cycles includes a polyp and a medusa stage

17. Body Plan
Polyp: cylindrical body with arm-like tentacles; mouth points upward
Medusa: motile, bell-shaped body; mouth on the bottom

18. Feeding
Polyps and medusas have a body wall that surrounds an internal space: the gastrovascular cavity
Gastrovascular cavity: a digestive chamber with one opening
Food enters and wastes leave the body

19. Respiration, Circulation, & Excretion
Following digestion, nutrients are usually transported throughout the body by diffusion
Respire and eliminate wastes by diffusion through body walls

20. Response
Specialized sensory cells are used to gather information from the environment
Nerve net: loosely organized network of nerve cells that together allow cnidarians to detect stimuli
Distributed uniformly throughout the body in most species
In some species it is concentrated around the mouth or in rings around the body

21. Response
Statocysts: groups of sensory cells that help determine the direction of gravity
Ocelli: eyespots made of cells that detect light

22. Reproduction: Sexually and Asexually
Polyps can reproduce asexually by budding
External sexual reproduction
The sexes are separate-each individual is either male or female
Both egg and sperm are released into the water

23. Groups of Cnidarians Jellies (formerly jellyfishes)
Hydras and their relatives
Sea anemones
Corals