classes of sponges and
sponge anatomy notes
HW:
Classes of Sponges
There are three different classes of
sponges:
– Calcarea
– Hexactinellida (Glass Sponges)
– Demospongia
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.
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.
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.
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.
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.
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.