Phylum Porifera. The Sponges. Typical sponges and their structure. Figure 12.04. I.Characteristics of Sponges. Multicellular – The body of sponges is a loose aggregation of cells Body containing pores , canals and chambers Mostly marine ; all aquatic
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Typical sponges and their structure
I.Characteristics of Sponges
Multicellular – The body of sponges is a loose aggregation of cells
Body containing pores, canals and chambers
Mostly marine; all aquatic
Symmetry is either radial or they have NO symmetry
Skeleton of proteins (collagen and/or spongin) with spicules
NO true organs or tissues
Adults are sessile and attached to substratum
II. Form and Function
A. Incurrent pores are called Ostia
B. Excurrent pores are called Oscula.
C. Specialized collar cells
create water flow and aid in digestion of small particles.
These choanocytes are located throughout The mesohyl - the matrix in which all sponge cells are embedded.
E. Special amebocytic cells, called archaeocytes,carry out a variety of functions – especially digestion and protein formation andspicule formation.
A. Calcareousspiculesare made of CaCO3. They are formed from the mineral elements
in the saltwater around them by special archaeocytes.
Spongin is a protein found in only SOME sponges – not all!
The simplest body plan is the Asconoid, where the choanocytes are located in the spongocoel, or hollow, internal, water filled gastrovascular cavity.
The second most complicated sponge body plan is the Syconoid sponge. It’s choanocytes are located in Radial Canals.
The largest and most complicated sponges by far are the leuconoid sponges. They have their choanocytes in flagellated chambers, which increase water flow and feeding efficiency.
A. ClassCalcarea – Heavily calcareous sponges containing
straight calcareous spiculesand collagen
B. Class Hexactinellida– radially symmetrical deep water sponges with six-rayed siliceous spicules. These are often beautiful and range from a few centimeters to more than 1.3 meters in length , and contain collagen.
C. Class Demospongia– By far the largest group, containing 95% of all living sponges in the world. Spicules are siliceous, but not six rayed. They may or may not contain spongin, but like all sponges , they do have collagen.
Two examples of the remains of Euplectella
D. There is another group of sponges, called the Sclerospongiae that are currently classified as Demosponges. They have been classified in their own Class Sclerospongiae, but are now classified with the Demospongiae. These are all found in dark crevices in the ocean and are seldom found in the open, and are usually fairly colorful. It is possible that they may become their own class again in the future.
A. Asexual Reproduction:
Carried out by budding (fragmentation) OR
by gemmules – internal buds created to allow
them to withstand adverse weather conditions;
usually over the winter.
B. Sexual Reproduction:
Carried out by normal sperm and egg process; sperm
are usually carried out of the osculum of one sponge
and into the ostia of another. All sponges are
hermaphrodites – containing both male and female