Phylum Proifera (Sponges)

Phylum Proifera (Sponges)

1. Body Plan

   • Anatomy
     • Cylindrical-Like Pipe
     • Spongocoel
       • Space cavity or space between the body wall
       • osculum
         • large opening at the upper end
     • spicules/spongin
       • Several functions: *Structural support  *resist compression by water *resist negative pressure of choanocyte driven pressure gradient Composition: Spicules are made of calcium carbonate or silicon salts. Spongins is made of a tough fiberous protein similiar to collagen
     • Bodywall
       • Pinacocytes
         • epidermal like cells
       • choanocytes
         • specialized cells inside the bodywall
         • cell body
         • flagellum
         • collar
         • microvilli
     • amoebocytes
       • Functions: 1) Take up food from the surrounding water and from choanocytes. They digest the food and move it to other cells.  2) Manufacture tough skeletal fibers within hte mesohyl *spicules *spongin 3) Can become any type of cell in of sponge cell.  *totipotent *allows sponge to adjust to the physical environment *allows the sponge to regenrerate
     • mesohyl
       • gelatinous matrix that separates the two layers of cells. *skeletal fibers are embedded here
     • Incurrent canals
     • Radial Canal

2. Food acquisition

   • Filter feeder
     • filter feeders filter out food particles supended in the water 
     • Process
       • The choanocytes flagellum will start beating which creates a current that draw water through the incurrent cannals or pores. The water will exit through the osculum. As the water moves through the spongocoel toward the osculum some of it will also go through the collar of the choanocytes. The collar is composed of microvilli which has mucus that coats its surface. Food particles get trapped in the mucus. By phagocytosis the food particles are engulfed. The food particles are either digeted or transfered to amoebocytes. 

3. Reproduction

   • broadcasters
     • release millions of gametes and embryos into the water
   • hermaphrodites
     • Most sponges practice sequential hermaphroditism. This means in one point in time they function as one sex and at another time they function as another sex. 
   • Process
     • Millions of sperm are released from a male functioning sponge. The flagella from from choanocytes will help disperse the sperm. Once dispersed the water current will bring the sperm to a female functioning sponge. The egg on the female functioning sperm will become fertilized. Cross-fertilization occurs. The zygote will turn into a flagellated swimming larvae that will stick to a substrate. The larvae will then develop into a sessile adult. 

4. How sponges clarify evolution of multicelluar animals

5. Sponge Diversity

   • 5000 species
     • Differ in  types of spicules patterns in folding of body wall Bigger size required more folding. Smallest have no folding.  shapes, colors, sizes, 

6. Ecology

   • Sponges help keep clear water in reef ecosystems
   • Few predators
     • Sponges spicuoles make them hard to eat 
   • Pharmacology
     • Sponges produce a variety of antibiotics and other compounds that can be used to fight infections and cancer cells.  
     • Why these compounds are produced in sessile animals
       • fungus and bacteria tend to grow on them

7. Ecological Niche

   • Sessile Benthic
     • Sessile
       • permanently attached to something
     • benthic
       • live on the bottom in the aquatic habitats
     • Challenges
       • 1) Acquiring food 2) Reproduction 3)Predation 4) Lower Oxygen in ocean for cellular reproduction 5)Harder to attach to a substrate 6) Competition for space