Sponges are Metazoans, simple
Sponges show the cellular level of organization, division of labor among cells, no organs, no systems, no mouth or digestive tract, rudimentary nervous integration.
sessile in form, no germ layers, neither dipoblastic nor triploblastic, some have no regular form or symmetry, can be either solitary or colonial.
1) Pores and canal systems
2) choanocytes- flagellated sponge feeding cells which line the sponge's cavities and creates currents of water
3) peculiar internal skeletons composed of spicules (organic fibers)
4) Some form of internal cavity (spongocoel) that opens to the outside by an osculum.
Sponges with spicules of calcium carbonate, needle-shaped or three-rayed or four-rayed; canal systems asconoid, syconoid, or leuconoid, all marine.
Sponges with three dimensional, six-rayed siliceous spicules, spicules often united to form network, body often cylindrical or funnel-shaped, canal systems syconoid or leuconoid, all marine, mostly deep water.
Sponges with siliceous spicules (not six-rayed), spongin, or both. Canal systems leuconoid, one family freshwater, all others marine.
Sycon (a Syconoid Sponge)
-Strictly marine, lives in clusters attached to rocks, pilings or shells.
Sycon chiefly a North Atlantic form
Sycon body wall:
tiny, interconnected, dead-end canals whose flagellated cells draw in water from the outside through minute pores, taking from it necessary food particles and oxygen, then empties it into spongoceol (body cavity)
Body cavity inside sponge
Osculum- opening at end, little mouth, surrounded by fringe of stiff, rod-like spicules.
contained in innumerable, fingerlike processes pointing out, closed at outer end but opens into central cavity, the spongocoel.
external spaces between radial canals
minute openings through which water moves from incurrent canals to radial canals and then to spongocoel.
minute pores that open from radial canals into the spongocoel.
in skin, through which water and food comes in
gelatinous matrix in which sponges are loosely arranged, connective tissue of sponges
create a flow of water into the sponge pores by collectively moving their flagella.
wander through the mesohyl with various functions: spicule-forming cells, sex cells, secrete spongin or spicules, serve as contractile cells, or aid in digestion
Monoecious, having both male and female sex cells in the same individual
Eggs and sperm produced in the mesohyl
Embryos are amphiblastula larvae
Zygote develops into a parenchymal larva
Some are Asexual, budding off new individuals from their base.
Short monaxons (short and pointed at both ends), long monaxons (long and pointed), triradiates (y-shaped with three prongs, and polyaxons (t-shaped) are spicules of calcium carbonate that forms network in the walls of the animal.
Asconoid Canal System
in sponges, Calcarea, grows in cluster or colony of tubular individuals in varying stages of growth.
Leuconoid Canal System
Most sponges are this type and belong to class, demospongiae.
Have clusters of flagellated chambers lined with choanocytes and water enters and leaves via systems of incurrent and excurrent canals.
Of the three sponge types, which is the most common?
Sponges with a leuconoid type of canal system, belonging to the class demospongiae,
first as males, later as females.
larvae swim, then settle.