CHAPTER IX 

 SPONGES, AND SPONGE FISHING 



The sponges are fixed, aquatic, plant-like animals living 

 mostly in salt water. They are regarded as representing the 

 simplest type of Metozoan body structure and cell specializa- 

 tion, and are classified as a branch of the animal kingdom 

 called Porifera. The body of the simplest sponges is vase- 

 shaped or cylindrical with the base attached to a rock or shell 

 or other firm substance. At the free end there is an opening 

 that leads down into the central cavity. The walls surround- 

 ing this cavity are perforated by numerous openings or canals 

 through which the water flows. 



Few sponges are of this simple vase-like appearance, how- 

 ever. Most of them are unsymmetrical, and cling close to 

 the surface on which they grow, or form low compact bushy 

 bodies looking much more like plants than like animals. 



Sponges belonging to the genus Grantia are convenient types 

 for study. They live in salt water and may be 1 obtained at 

 many points on the Atlantic or Pacific Coasts on rocks, 

 shells or other objects below low water line. They are sub- 

 cylindrical in form, attached at the base, and with a rather 

 large opening, the exhalant opening, or osculum, at the free end. 

 All over the sides are numerous small openings leading into the 

 inhalant canals which extend almost to the inner or gastric 

 cavity or cloaca. Opening into the cloaca and extending 

 almost to the outer wall are other canals, the radial canals. 

 The inhalant and radial canals run side by side and communi- 

 cate with each other by means of very small openings. The 

 cells lining the radial canal are furnished with long lashes, or 

 flagella, the lashing of which sets up currents of water which 



1 Inland schools can obtain specimens preserved in alcohol or formalin 

 from dealers in natural history supplies. 



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