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The Sponges — Phylum Porifera 



Porifera, the name of this second phylum, means to bear pores ; and 

 all members of it have tiny holes perforating their bodies, so the name 

 is very appropriate. Commonly we refer to these animals as sponges. 

 For a long time they were thought to be plants because of the fact that 

 they spend most of their lives attached in one place and are not active 

 in the sense that most animals are. Morphological studies, however, 

 have definitely placed them in the animal kingdom. The bath sponge, 

 with which everyone is familiar, is a common member of this phylum 

 and, because of its porous nature, it is able to hold large quantities of 

 water. However, the bath sponge is not a typical genus of this phylum, 

 so we will pick another genus, Scypha, as a type animal. 



A Simple Sponge 



Scypha is a small vase-shaped sponge about an inch in height which 

 lives attached to rocks or other solid objects in shallow salt water. It 

 lives only in salt water and thus may be spoken of as a marine animal 

 in contrast to a fresh-water animal. Examination with a hand lens or 

 microscope will reveal the many tiny pores that are found all over the 

 body. Also, it will be noticed that the body is covered with sharp spines, 

 called spicules, that serve to support the softer parts of the body and, 

 therefore, we might think of them as forming a primitive sort of skele- 

 ton. These spicules are composed of calcium carbonate. Because they 

 are sharp and project out all over the body, they also act as a dis- 

 couragement to any animal that might wish to nibble on them. At one 

 end of the body you will see a large opening which is called the osculum; 

 at the other end is the point of attachment. 



Scypha has an interesting method of ingestion; cells which line the 

 canals running through the body bear flagella which keep a constant cur- 

 rent of water flowing into the pores, through the canals into the cloacal 

 cavity in the center, and, finally, out through the osculum. This water 

 contains disintegrating bits of organic matter and small living organisms 

 which may be used as food; the cells engulf this food as it passes 

 by. We might compare this to a cafeteria where the patrons go in and 



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