366 THE LIVING ANIMALS OL THE WORLD 
SPONGES AND ANIMALCULES 
T he Sponges are regarded as a group standing on the border- 
land between the Polyps and the lowly organisms which 
follow. The familiar Batpi- 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, however, 
agree with one another in the identity of their most essential vital 
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 extent 
by minute holes or pores, 
while one or more holes of 
relatively large size occupy 
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 by 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 by 
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 Neptune’s-cup Sponge, like a huge chalice 
3 or 4 feet high, indigenous to the South Seas; the 
wonderful cornucopia-shaped L.\CE-SP0NGE, consisting of 
a lace-like reticulation of flinty fibres ; and its near 
ally the Glass-rope Sponge, forming a cup- or bird’s- 
nest-shaped body, supported on a long cylindrical stalk 
Photo by Saville-Kenty F.Z.S,^ Mtlford-on-Sea 
reticulated sponge 
The skeleton of this sponge is composed of fine 
horny fibres resembling those of ordinary 
commercial sponges 
Fhotahy W. Savilli-Ktnt, F.Z.S., 
Milford-on-Sea 
FRILLED SPONGE 
species not infrequently dredged 
up by the pearl-shell fishers in 
Sharks’ Bay, Western 
Australia 
