1. classes of sponges and sponge anatomy notes
HW:

2. Classes of Sponges There are three different classes of sponges:
Calcarea
Hexactinellida (Glass Sponges)
Demospongia

3. Canal Systems
Canal systems refer to method of water flow throughout the sponge.
There are three different types of canal system:
Simple (asconoid)
Water enters spongocoel by incurrent openings of the pore cells. Cells lining the spongocoel absorb the nutrients and oxygen and left over water is expelled through the osculum.
Advanced (Syconoid)
The body wall is folded, accomodating more pores without increasing the size of the sponge.
Complex (Leuconoid)
This canal system is extensively branched, and thus more complex.

4. Calcarerous Sponges
Sponges of the class Calcaera are known as calcareous sponges.
Their specific characteristics include:
are usually small (4” in height).
Found in shallow waters
Skeletons are made up of separate spicules of calcium carbonate.

5. Calcaerous Sponges There are two different varieties: Leucosolenia
These are the simplest sponges that have a simple canal system.
Scypha
These contain an advanced canal system.
There are also calcareous sponges that have a complex canal system.

6. Class Hexactinellida This class is commonly known as glass sponges.
Their specific characteristics include:
Skeleton consists of six-pointed spicules fused in a geometric pattern.
Found in deep, tropical waters.
Possess an advanced canal system.

7. Class Demospongia This class contains that largest number of sponges.
They are also the most marketable sponges, often used as cleaning products.
Their specific characteristics include:
Skeleton consisting of elastic (spongin) fibers, silicon dioxide, or a combination of the two.
It is the elastic nature of the skeleton that makes them spongy.
They possess a complex canal system.

8. Sponge Anatomy Sponges have the following types of cells:
Epidermal cells – line the outside of the sponge.
Pore Cells – Which extend through the body wall of the sponge to allow water in.
Gelatinous Layer – The middle layer of the body wall that is jelly-like and contains mobile amoeboid cells.
Amoeboid Cells – mobile cells that move around the sponge, secrete spicules, and are responsible for digestion.
Spicules – are the calcium carbonate structures that are imbedded in the body wall of the sponge to support it.
Collar Cells – Line the internal cavity (spongocoel), and have flagella used to catch food particles.