STARFISHES, URCHINS AND SEA-CUCUMBERS 53 
The mouth is at the centre of the lower side of the disk and is sur- 
rounded on all sides by the tube-feet. 
In summer and autumn the starfishes are found on rocky 
places in shallow water, but in winter they live at greater depths. 
Starfishes feed upon almost any kind of mollusk, but will also 
devour barnacles, worms, and occasionally sea urchins or even the 
young of their own species. It is estimated that in 1888 starfishes 
destroyed $631,500 worth of oysters on the beds of Connecticut 
alone. Their mode of feeding is interesting. The starfish folds 
its arms over the clam or oyster, and hundreds of the sucker-like 
tube-feet fasten themselves to the valves of the shell, so that finally 
the mollusk yields to the constant pull of the starfish, and the shell 
gapes open. ‘Then the starfish turns its stomach inside out and 
engulfs the mollusk. It has been found by experiment that a large 
starfish can exert a steady pull of over two and one-half pounds and 
that this is sufficient in time to open the valves of a clam or mussel. 
The eggs of the starfish are discharged into the water in great- 
est abundance during the last three weeks of June, although they 
are also to be found throughout the summer, and occasionally even 
in winter. These eggs soon develop into little transparent larvee cov- 
ered with tortuous lines of waving cilia, and provided with long 
flexible tubercles. They swim slowly about near the surface, and 
feed upon minute organisms until they grow to be about one-eighth 
of an inch long. Then the upper and lower halves of the star be- 
gin to develop upon both sides of the stomach, and in a few hours 
all of the anterior part of the larva and the tubercles are absorbed, 
and only a minute star, about as large as a pin’s head, is seen upon 
the bottom of the ocean. 
Myriads of these little stars settle upon sea weeds and eel grass, 
and begin at once to devour the young clams which also begin life 
in the same places. Professor Mead found that one of these little 
stars devoured over 50 young clams in 6 days. The starfishes grow 
rapidly, and in one year they may have arms 23 inches long and be 
ready to spawn. 
It is certain that the menhaden devour myriads of starfish larvee 
as they swim through the water. 
Normal starfishes have five arms, but occasionally one is found 
