PORIFERA Flashcards
Main characteristics of Phylum Porifera?
-Parazoan - no true embryonic tissues
-Cells are pluripotent - they change form and function and they are mobile throughout the body.
-An aquiferous system pumps water throughout the sponge body.
What are the 4 classes of sponges
Calcarea
Demospongiae
Hexactinellida
Homoscleromorpha
Characteristics of Class Calcarea?
-Spicules composed of calcium carbonate
-Exclusively marine
-Considered the most primitive of sponges
-Color usually dull
Characteristics of Class Demospongiae?
-95% of extant species in this group
-Siliceous (hydrated SiO2) spicules or organic collagen network
-Marine and freshwater
-Only a few freshwater species
-Occur at all depths
Characteristics of Class Hexactinellida?
-“Glass sponges”
-Siliceous, six-rayed spicules
-Exclusively marine
-Found primarily in deep water
Characteristics of Class Homoscleromorpha?
-Small group of encrusting sponges
-Most have no spicules, if they do the spicules are small and siliceous.
-Exclusively marine
Describe the Aquiferous System of a sponge
-Water is pumped through the sponge such that O2 and nutrients are brought in and CO2 and wastes are removed.
-Sponge walls have pores and chambers so each cell is in close proximity to water.
Describe the body structure of a sponge
-Layers of cells with specific functions.
-Contribute to aquiferous system, food uptake, and support.
-Mesohyl - noncellular mesohyl which contains spicules and many types of ameboid cells.
What is the pinacoderm
Outer layer perforated with small pores where water enters. Made of pinacocytes
What are pinacocytes
flattened and overlapping.
Epithelial function and are probably phagocytic.
Osmoregulation in freshwater sponges.
Dermal pores - one cell or more than one cell?
pores composed of more than one cell
Osita - one cell or more than one cell?
pores composed of only one cell
What cells make up pores?
Porocytes
Describe the choanoderm and the cells that make it
Choanoderm is the inner surface that is made of choanocytes
-Surface of flagellated cells that creates water currents
-Collar of microvilli with flagellum in middle
-Collar has mucus to trap food particles
What are the 3 body types of sponges?
Asconoid
Synconoid
Leuconoid
Describe the Asconoid body type
-Small and simple vase shape
-Pinacoderm and choanoderm are simple sheets
-Porocytes are tube-shaped cells that form ostia on pinacoderm side and open into spongocoel on choanoderm side
-Found in all juvenile and some adult calcareous sponges
-Water flow:
ostia → porocyte → spongocoel → osculum
Describe the Synconoid body type
-Various degrees of infolding to create flagellated chambers containing choanocytes
-Mesohyl thickened
Incurrent opening is a dermal pore surrounded by several porocytes
-A system of canals leads to the flagellated chambers
-The opening into the chamber is the prosopyle
Chambers open to the spongocoel via a wide opening called an apopyle
-Found in many calcareous sponges.
-Water flow:
dermal pore → incurrent canal → prosopyle → flagellated chamber → apopyle → spongocoel → osculum
Describe the Leuconoid body type
-Further infolding of pinacoderm and choanoderm to create flagellated chambers that are discreet chambers
-Spongocoel is a series of excurrent (or exhalent) canals
-Flagellated chambers have large surface area compared to incurrent and excurrent canal systems
-Decreases water velocity to maximize gas and nutrient exchange
-Typical of most calcareous and all demosponges
-Water flow:
dermal pore → incurrent canal → prosopyle → flagellated chamber → apopyle → excurrent canal → osculum
How do sponges support themselves?
Collagen and/or Spicules
What type of cells produce spicules?
Sclerocytes
How do sponges protect themselves?
Spicules and Biotoxins
How do sponges feed?
Phagocytosis and pinocytosis for intracellular digestion
How do sponges reproduce Asexually?
Asexual reproduction:
-Fragmentation - small bits break off and form a new sponge
-Budding - new sponges grow attached to an older sponge and eventually form a new sponge
-Gemmules - overwintering bodies of freshwater sponges
How do sponges reproduce sexually?
-Most sequential hermaphrodites, but some gonochoristic
-Most sponges release egg and sperm into water
-Fertilization typically external
What type of larvae do sponges have?
Motile (swim and creep), lecithotrophic
What is the mesohyl
a layer between the pinacoderm and choanoderm. Can be very thin or very thick
