THE LIVING ANIMALS OF THE WORLD 



CHAPTER Vl\ 



SPOXGES AND JXIMJLCVLES 



THE Sponges are regarded as a group standing on the border- 

 land between the Polyps and the lowly organisms which 

 follow. The familiar Bath- and ToiLET-SPONGES of com- 

 merce represent but an insignificant fraction in comparison with the 

 many hundred species which find no place in the world's market. 

 Toilet-sponges owe their intrinsic value to the relative fineness and 

 elasticity of their component fibrous skeletons. In these particular 

 species the skeleton is composed of a substance akin to horn. In 

 other sponges the skeleton may consist of horny fibres mi.xed with 

 flinty spicules, or it may be of flint only, or of spicules of carbonate of 

 lime. Finally, there are sponges which possess no internally support- 

 ing skeleton, fibrous or spicular, and whose substance is consequently 

 little more than gelatinous. All these numerous forms, howe\er, 

 agree with one another in the identity of their most essential \ital 

 elements. In the living sponge the skeleton, fibrous or otherwise, 

 is embedded within a gelatinous matrix by whose component cells 

 it is excreted. Externally the sponge-body is perforated over the 

 greater portion of its e.xtent 



Mtlf«rd-on-St,i 



FRILLED SPONGE 



A species mt infrequently dredged 



up by the pearl-shell fishers in 



Sharks' Bay, IVestern 



Australia 



by minute holes or pores, 

 while one or more holes of 

 relatively large size occup)' 

 the summit of the sponge, 

 or are scattered here and 

 there among the numerous 

 smaller pores. The smaller 

 pores represent incurrent ap- 

 ertures, and lead to chambers 

 within the sponge's substance 

 lined b}- cells. Each of these 

 is provided with a long whip- 

 like appendage, with a trans- 

 parent wineglass-shaped cup 

 or collar, which is a beautifully constructed food-trap. 

 The lashings of the whips of the collar-cells cause 

 currents of water bearing nutrient particles to flow in 

 at all the smaller pores. Arriving at the chambers, 

 these particles are caught by the outstretched collar-traps 

 and absorbed into the cell's substance. The water, 

 together with rejected and waste materials given off b\- 

 the sponge-body, is carried forward, and passes out at the 

 larger orifices or vents. 



Among the more remarkable sponges may be men- 

 tioned the Neptuxe's-cup Spoxce, like a huge chalice 

 3 or 4 feet high, indigenous to the South Seas; the 

 wonderful cornucopia-shaped L.\CE-SPon'GE, consisting of 

 a lace-like reticulation of flinty fibres; and its near 

 ally the Gl.\SS-ROPE Sponge, forming a cup- or bird's- 

 rest-shaped body, supported on a long cylindrical stalk 



ThtM hy U: Saiilli-Kinl, F.Z.S., Milfird-tn-Sra 



RETICULATED SPONGE 



The skeleton of this sponge is composed oj fin"- 



horny fibres resembling those of ordinary 



commercial sponges 



