complexity far beyond anything seen in calcareous 

 sponges. The rays may be covered with spines, their 

 tips branched like brushes or feather dusters, or ex- 

 panded into umbrellas or recurved anchors. They oc- 

 cur as separate particles, and in most members of 

 this class are also hooked together into loose skeletal 

 networks or firmly fused into rigid lattices of open 

 structure that support delicate cellular complexes. 



Most glass sponges are radially symmetrical and 

 grow as solitary cylinders, vases, cups, or funnels, 

 drab or white in color. Some are branching or have 

 the branches fused into latticework. They are of mod- 

 erate size, from 4 to 12 inches, but there are species 

 3 feet long; and a form like Mononiphis is much 

 longer if we count its tremendously extended anchor 

 ( 6 to 9 feet long and almost Vi of an inch thick ) . 



The beachcomber will find no glass sponges. They 

 are all deep-water forms, reaching their peak of 

 abundance on bottoms three thousand feet or more 

 below the surface, and then tapering off in numbers 

 as they extend down into the great abyssal regions of 

 the oceans. The glass sponges are among the finest 

 rewards of dredging in the great deeps ofi' the West 

 Indies, the Philippines, the Molucca Islands, and Ja- 

 pan. N. B. Marshall, in Aspects of Deep Sea Biology, 

 quotes from Alcock's recollection of trawling in the 

 Indian Ocean: "As the trawbag came clear of the 

 sea, it seemed at first sight as if it had fouled a sunken 

 haystack, for there stuck out on all sides things that 

 looked like bundles of hay, with here and there a 

 bird's nest attached, which on closer inspection 

 turned out to be great Hexactinellid sponges." In the 

 deep waters to the west of the European coasts Le- 

 Danois has found the cup-shaped Asconema and the 

 vaselike Pheronema to be quite co.mmon. as are also 

 species of the glass rope sponge Hycilonenui. The 

 name means "glassy thread," but the dried skeleton 

 of a Hyalonema is better described as looking like 

 an upturned bell-shaped wad of glass wool with a 

 long, opalescent handle of spirally twisted spun-glass 

 fibers. The tuft is a bundle of greatly elongated 

 spicules that end in recurved hooks; and it splays out 

 at the end, anchoring the living sponge firmly in the 

 soft ocean floor. At its upper end this column of fi- 

 bers protrudes into the body of the sponge and may 

 even push up the perforated exhalant surface into a 

 projecting cone, eliminating any sort of cavity in the 

 upturned bell. Off the New England coast a species 

 of Hyaloiienui is found in only thirty to forty-five 

 feet of water, but even such forms have been, in the 

 past at least, inaccessible as living sponges to anyone 

 who could not manage to be on deck when a glass 

 sponge was dredged up. To most professional zoolo- 

 gists, glass sponges are known only from preserved 

 specimens or dried skeletons. 



The unvarying climate and the slow, continuous 

 current of deep waters are usually called upon to ex- 



The beautiful skeletons of Venus' flower basket, 

 Euplecfella. are all that most of us ever see of glass 

 sponges. (American Museum of Natural History) 



plain the adaptations of glass sponges, and especially 

 of such a form as Venus' flower basket, or Eiiplec- 

 tella, which is brought up from depths of fifteen hun- 

 dred to fifteen thousand feet off islands in the western 

 Pacific, especially the Philippines and Japan. As dis- 

 played in the showcases of museums, the elegant skel- 

 eton of Euplectella is a foot-long curved tube of glis- 

 tening siliceous open latticework. Strengthening the 

 upper end is a perforated convex sieve plate; and 

 bearding the lower end is a tuft of fibers that root the 

 living sponge. From top to bottom the tubular lattice 

 is wreathed with projecting ledges of fused siliceous 

 spicules that strengthen the framework and add to its 

 rigidity as well as to its loveliness. Within the closed 

 cylinder there usually is to be found a pair of 



61 



