2. Poriferans (sponges)
• ‘pore bearing’
• Spongocoel
• Choanocytes or Collar cells
• Archeocytes
• Epidermal cells
• Has Mesophyl sandwiched between two thin layers
of cells.

3. Defining Characteristics
• Microvillar collars
surround flagella, with
units arising from
either single cells or
syncytia.
• Lack nerves and no
true musculature.

4. Skeleton
• Sponges are either radially symmetrical or
asymmetrical.
• Mesohyl=Endoskeleton
• Spicules=Sclerocytes
• Spongin=Spongocytes

5. Food Capture and Digestion
• detritus particles, plankton, bacteria
• Choanocytes
• Food items are taken into individual cells by
phagocytosis, and digestion occurs within individual
cells.

6. Excretion and Water Balance
• A sponge has carbon dioxide and other wastes
removed as the water moves in and out through the
pores.

7. Respiration and internal Transport
• Diffusion of gases through the help of water
• Archeocytes remove mineral particles that
threaten to block the ostia.

8. Nervous System
• A sponge has a very low level reaction to the world
around it and does not have a brain per se.

9. Reproductive system
• Asexual
+fragmentation
+buds
*external buds
*internal buds or gemmules
• Sexual (mesohyl)
+eggs and sperms
+hermaphroditic
*External and internal fertilization

10. Development
• Hollow blastula or Coeloblastula
• Amphiblastula-the hollow sponge larvae
• Some species, from coeloblastula to
stereoblastula
• Larvae are incapable to feeding and swim
for less than 24 hours before
metamorphosing.

11. Ecology and Evolution
• 98% in marine
• 2% in water and mostly with spongin fiber
• Many in tropics
• Sponges have strong structures that are able
to handle the high volume of water that
flows through them each day
• release toxic substances into the
environment

12. PLACOZOANS (Flat plate)
• They were discovered in the late 1880's
living on the glass walls of an aquarium in a
European laboratory.
• Single species

13. Defining Characteristic
• Multicellular
• Amorphous
• Mobile
• flagellated animals lacking a body cavity, digestive
system and nervous system
• composed of 2 layers of epithelial cells.

14. • 2 distinct layers of epithelial cells
+ventral- columnar cells w/ flagellum
- Glandular cells with enzymes
- Endodermal
+Dorsal- Flat, thinner and No gland cells.
-Ectodermal
+In between- fluid
-Contractile fibrous cells.

15. Movement
2 Ways;
• gliding on their cilia
• changing their shape like an amoeba.

16. Digestion
• Atops the food using the Ventral surface
• No sign of phagocytosis
• Extracellular digestion

17. Reproduction
• Sexual
+ generally, produces one oocyte.
+developed embryos
• Asexual
+Budding
+Fragmentation
+Binary fission