A GUIDE TO THE SPONGE ALCOVE IN THE AMERICAN 

 MUSEUM OF NATURAL HISTORY. ' 



By Roy Waldo Miner, 

 Assistant Curator Department of Invertebrate Zoology. 



PONGES are among the most abundant and 

 most widely distributed of sea-animals. With 

 the exception of one family, the fresh-water 

 sponges, they are found in all seas of the globe 

 ranging from shallow waters to beyond a depth 

 of 1,300 feet. The bath-sponges of commerce, with which the 

 word "sponge" is associated in the minds of most people, 

 although from a commercial point of view the most important of 

 the group, form but a single family, i. e., the Spongidae. The 

 rest of the subkingdom with its great multiplicity of forms is 

 doubtless comparatively unknown to the average person. Even 

 the commercial sponge as it reaches us gives but little idea of 

 what a sponge really is, as it is only the supporting or skeletal 

 part of the animal colony denuded of its fleshy coat of living 

 tissue. 



The li\'ing sponge is either a single animal or a colony of 

 animals. It is always sessile, that is, attached to the sea bottom, 

 and incapable of locomotion. For this reason it has often been 

 regarded as a plant. But since, in more recent years, its life 

 processes and larval history have become better known, especially 

 since it has come under the eye of the compound microscope, 

 its animal nature has become clearly established. 



Sponges show all variations of form, size, and color. There 

 are cake-like sponges, dome-shaped sponges, and fan-shaped 

 sponges. Some are branched like trees; in others the branches 

 reunite to form a complicated network. Some are shaped like 

 huge cups or goblets; some gather in clusters of trumpet- and 



' Issued also in separate form as Guide Leaflet No 23. 

 219 ' 



