Neither of these properties, unfortunately, is covered directly 

 in the usual grading of sponges, but the graders are aware of their 

 significance and include many tests that reveal differences influenc- 

 ing the rate of wear and the action of -water in the sponge. The 

 quantitative tests given in the present report appeared to members of 

 the Sponge Exchange of Tarpon Springs, Florida, to have possibilities of 

 satisfactorily measuring these two properties, 



A more detailed discussion of the census that was taken on the 

 use of sponges is given in a later section in the present report, 



DESCRIPTION OF IMPORTANT SPONGES 



The only commercial l y important sponges in this part of the 

 world belong to the Keratosa family (De Laubenfels 1953, and Stuart), 

 Radiating from the base of these sponges, is an interlaced fiber 

 structure easily seen through a strong lens after the sponge has 

 been cleaned thoroughly. The fibers are the spongin skeletons of 

 the many small one-celled animals that make up the sponge. These 

 cells are capable of individual existence for some time and of 

 changing in form to assume one of the many duties of a colony of 

 sponge cells, such as taking in food or throwing off refuse through 

 separate channels set up for these purposes. 



Most people are familiar with the similar cooperation observed 

 in a colony of ants or in a hive of bees. The nearest analogy, but 

 one less familiar, is the colony that forms a coral structure. Here 

 the skeleton is of hard inflexible mineral matter. Even in sponges, 

 one encounters some with skeletons containing varying amounts of 

 minerals similar to sand or limestone. The skeleton of most sponges, 

 however, is enclosed in a jelly like material that the cells have 

 secreted and in which they can move. A mineral skeleton also may 

 have been formed by the cells, starting usually with sharp, pointed 

 spikes or spicules of mineral matter, which vary widely in shape, 

 size and amount. The spongin or horn-like animal skeleton, all- 

 important in the commercial Keratosa sponges, rarely is accompanied 

 by these mineral spicules, A few other commonly occurring sponges 

 such as the Loggerhead (not in the Keratosa group) probably would 

 have been developed commercially, however, if their spicules were 

 not so hard on the hands during the cleaning of the sponge. 



The commercially valuable sponges have almost no spicules to 

 injure the hands, and are given the description "Keratosa, 1-CC" 

 by De Laubenfels, followed by: "The fibers are solid and opaque. 

 The dried sponge is still spongy in consistency," (Either of these 

 usually is adequate for identification.) "It neither emits a strongly 

 colored exudate, nor a strong, unpleasant odor" when alive. 



The "sheepswool" (or wool) type of Keratosa includes Rock Island^ 

 Inshore, Cuban, Florida Key, and Mediterranean sponges, although for 



