SPONGES 105 
in these clear waters. The sponges are dragged up by hooks—a 
primitive method which restricts the fishing to shallow water, the 
fishing here being in water not deeper than thirty feet, but usually 
three to twenty feet. The sponges are “killed” by being exposed 
on the beach for several days; they are then placed in “crawls,” 
or pens, where they are washed by the action of the waves for 
about a week; then, if clean, they are dried, assorted, strung on 
cords, pressed and baled for shipment. The sponge-fisheries are 
of considerable value, and much attention is being given to the 
subject of artificial propagation. It is thought that such beds 
could be subjected to the regulations which govern oyster-beds. 
Already the planting of sponges has been shown to be practi- 
cable. The living sponge is cut to pieces, and the cuttings are 
placed in favorable localities. Pieces planted in Florida waters 
attain a marketable size in one year. 
Sponges reproduce by eggs formed in the mesoderm. The 
eggs escape as ciliated spheres and swim about until they find a 
place on which to attach themselves. As soon as they become 
fixed they grow with much rapidity into mature individuals. 
Some species seem to prefer association with other animals and 
live as commensals with crabs. The crab Dromia is always con- 
cealed under a sponge, which grows upon its back. Spider-crabs 
are often overgrown with sponges as well as seaweeds. In this 
case, however, the crab finds and plants the sponge himself. 
Aplysella violacea overgrows worm-tubes. Many sponges afford 
shelter to numerous small animals which bore into their bodies 
for protection, no animal seeming to feed upon the sponge. 
Sponges may be found in tide-pools, on the under side of 
stones, on seaweeds, and so on. A small bright-red incrusting 
sponge with irregular lobe-like branches is common on the New 
England coast; a thin yellow incrusting sponge also is found on 
the under side of stones. Grantia ciliata, a small urn-shaped 
species, having a large aperture at the summit, is found in tide- 
pools. 
Perhaps the most singular in habit of any sponge is Cliona 
sulphurea, the boring-sponge, a common species found from Cape 
Cod to South Carolina and abundant in Long Island Sound. It 
