THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YOL. III. 



New York, May, 1882. 



No. 5. 



The Boring Sponge— Does it Ex- 

 cavate tlie Burrows in 

 which it is Found ? * 



BY J. D. HYATT. 



The little sponge Cliona celata, Grant, 

 Hymeniacidon cdata, of Bowerbank, is 

 a common inhabitant of the waters 

 around New York, and is also well- 

 known on the coasts of the Brit- 

 ish Islands. Bowerbank, one of the 

 best authorities on the subject of 

 sponges, describes it as one of the 

 simplest in anatomical structure of 

 all the British species, and when we 

 remember that the highest organisms 

 of the order porifera are at most but 

 a step removed from protozoa, it will 

 not appear strange that many natu- 

 ralists still doubt the ability of Cliona 

 to excavate for itself the canals and 

 spaces which it always occupies in 

 rocks, shells and stones. 



The living part of a sponge is a 

 mere mass of jelly, or an aggregation 

 of jelly-like bodies which, together, 

 form a compound animal; but the 

 individual members composing this 

 animal may be separated from each 

 other, and from the mxain body, with- 

 out in the least impairing the other's 

 vitality. 



The only organ possessed by these 

 little sponge-bodies is a vibratile cili- 

 um, or lash, the rapid motion of which 

 serves the purpose of producing cur- 

 rents of water outward, through the 

 osculae, the inward flow being fil- 

 tered through the numerous minute 

 apertures or pores which open directly 

 into the internal cavities. These cur- 

 rents seem to convey to the sponge 



* Read before the New York Microscopical 

 Society. 



such matters as are suitable for food; 

 and this simple process is all that is 

 required for the purposes of nutrition. 



Sponge-colonies thus acting to- 

 gether, secrete for the whole a skele- 

 ton, or framework, which, in those 

 most familiar to us, consists of the 

 horny material which constitutes the 

 sponge of commerce. 



Imbedded in the body of the sponge 

 we often find also silicious or calcar- 

 eous spicules, of many fanciful shapes^ 

 resembling pins, needles, clubs, 

 crosses, anchors, wheels, hooks, etc. 



The framework of Cliona is almost 

 entirely silicious, the spicules taking 

 the form of pins, having a rounded 

 head at or near one extremity, while 

 the other terminates in a fine point 

 (fig. 26). Some naturalists have sup- 



FiG. 26 



posed that these spicules were the 

 tools used by this sponge in excavating 

 rock and shells, but the evidence 

 that they are used for this purpose 

 hardly warrants the definition of Cli- 

 ona given in the " Micrographic Dic- 

 tionary," edition of 1875, which is as 

 follows; " Cliona, Grant — A genus of 

 marine sponges. By means of the 

 spiculpe imbedded in their surface, 

 they burrow into rocks, shells and 

 stones." The evidence that this 

 sponge burrows by means of its spicu- 

 les, is not only wanting, but the suppo- 

 sition that it burrows at all, would seem 



