Phylum Porifera are primarily what
marine animals consisting of loosely organized cells
2 types of symmetry
asymmetrical or radial
3 cells types
pinacocytes, mesenchyme cells, choanocytes
What surrounds the central cavity
canals through which water circulates during filter feeding
Do they contain tissues or organs?
no
Are they sessile? (do not move)
yes
Pinacocytes
thin, flat cells that line the outer surface of a sponge
What can pinacocytes be specialized into that regulates water circulation?
porocytes
Mesenchyme cells
a jellylike inner layer that hold cells
What are mesenchyme cells responsible for?
reproduction, secreting skeletal elements, transporting and storing food and forming contractile rings around openings in the sponge wall
What is another name for choanocytes?
collar cells
What does the flagellum do?
creates water currents through the sponge
What does the collar do?
filters microscopic food particles from the water
What are sponges supported by?
a skeleton that may consist of spicules
Spicules
microscopic needlelike spikes
What are spicules made of?
calcium carbonate, silica, or spongin
Spongin
a fibrous protein made of collagen
How is a commercial sponge prepared?
by drying, beating, and washing a spongin-supported sponge until all of the cells are removed
Is the makeup of the sponges skeleton used in classification?
yes
What do sponges feed on?
bacteria, microscopic algae, protists, and other suspended organic matter
A small sponge can filter how many liters of water everyday?
20
Is filtration the only way that sponges feed?
no
Pinacocytes lining incurrent canals can __________.
phagocytize larger food particles
What can sponges absorb?
nutrients dissolved in seawater by active transport
Can sponges be carnivorous?
yes
What kind of animals can carnivorous sponges catch and how?
small crustaceans using spicule-covered filaments
Why are all sponge cells in close contact with water?
because of extensive canal systems and the circulation of large volumes of water through sponges
What role does diffusion play in the body of a sponge?
it rids the body of ammonia and applies gas exchange
Do sponges have nerve cells to coordinate body functions?
no
How to most reactions occur?
individual body cells responding to a stimulus
Monoecious
both sexes occur in the same individual
Are most sponges monoecious?
yes
Why don't sponges usually self fertilize?
because individuals produce eggs and sperm at different times
Are choanocytes in most sponges?
yes
What do choanocytes undergo?
they undergo meiosis to form egg and sperm, which are released through the sponge oscula
What type of fertilization do sponges have?
external
What is the exception to the type of fertilization that occurs?
in a few sponges, eggs are retained in the parent and fertilization occurs in the jellylike layer of the mesophyl
asexual reproduction of fresh water and some marine sponges involve what?
gemmules
What is the formation of resistant capsules?
gemmules
What can gemmules survive
both freezing and drying conditions
What happens when favorable conditions return?
amoeboid cells stream out of the top and organize into a tiny sponge
Can sponges regenerate?
yes
Class Calcarea
the spicules are composed of calcium carbonate; spicules are needle shaped or have 3 or 4 rays, all are marine
What is another name for the Class Calcarea?
Calcareous Sponges
Class Hexactinellida
spicules are composed of silica and are six rayed; spicules are often fused into an intricate lattuce; found in tropical West Indies and eastern Pacific
What shapes can the Class Hexactinellida be found in?
cup or vase
What is another name for the Class Hexactinellida?
glass sponges
Class Demonspongiae
colored sponges with needle shaped or four rayed siliceous spicules or sponging- can have both; mostly marine but has one freshwater family of sponges