1 6 A NATURAL HISTORY OF THE SEAS 



crustacean with merely a small opening to obtain its 

 food. 



The Glass Sponges, which belong to the group of 

 siliceous sponges, come from deep water, usually in tropic 

 seas, and include some of the most beautiful species known. 

 The skeletons are built up of large six-rayed spicules, 

 which combine to form intricate and exquisite designs. 

 The Glass-rope Sponges from Japan are remarkable for 

 a species of root-tufts of immensely long spicules which 

 form a tassel of what appears to be finely spun and very 

 flexible glass threads, the whole somewhat suggestive of a 

 flat-tailed fly whisk. The Glass-rope, as it is aptly called, 

 serves in life as an anchor holding the upper portion or 

 sponge proper securely to a muddy sea floor. The first 

 specimens acquired in this country were supplied by 

 Japanese dealers, who by way of adding to the specimens' 

 interest fixed the glass rope into pieces of coral — a piece 

 of trade deception which mystified scientists until living 

 specimens were finally obtained by the dredge. 



Some smaller but similar sponges are found off Portugal, 

 and both there and in Japan are commonly brought to 

 the surface attached to the hooks of fishermen. 



The common or fleshy sponges are abundant in all 

 seas and comprise a great variety of forms. The Boring 

 Sponge (Cliona) is too abundant to please those responsible 

 for oyster farms or the maintenance of sea walls. It 

 tunnels both oyster shell and hard lime-stone boulder 

 until the solid matter is reduced to so much honeycomb 

 and disintegrates from erosion. A peculiar boring sponge 

 excavates long galleries in the oyster's shell, covering the 

 outside of the shell with a slimey film of white or creamy 



