18 SEA-SHORE LIFE 
these deep-sea creatures belong to types which once lived in shallow 
water along our coasts, but which died out long ago, and are 
known to us only through their fossils in the rocks. 
Marine animals are much more abundant along or near conti- 
nental coasts than in the open sea far from land, for we must bear 
in mind that animal life can subsist only upon plant life and that 
the great food supply furnished by the shallows of a shore are most 
favorable for the development of a varied fauna. 
The great ocean currents, such as the Gulf Stream in the At- 
lantic, and the Kuroshiwo of the Pacific are the bearers of vast 
hordes of floating creatures which are thus carried from the tropics 
far into the temperate regions. Temperature is also a great factor 
in determining the distribution of marine life. On our own coast, 
for example, we find that the cold arctic water creeps down the 
New England coast to Cape Cod, while south of that place the shore 
water is warmed during the summer by the drift from the Gulf 
Stream. Accordingly a great number of southern forms extend 
only as far north as Cape Cod, and similarly many of the arctic 
creatures can not survive in summer in the warm water south of 
that cape. 
It is even more interesting to see that at Cape Breton, Nova 
Scotia, we find a number of creatures whose true home is south of 
Cape Cod, Massachusetts, but which are able to lve in the warm 
water at the mouth of the St. Lawrence, where the Gulf Stream 
approaches the coast for the last time before its final deflection 
into the midst of the Atlantic. 
So important is temperature in determining the distribution 
of marine life, that while the creatures of the tropical Atlantic and 
Pacific on opposite sides of the Globe are, broadly speaking, quite 
similar, those living north of Cape Cod are almost wholly different 
from those of the Florida coast. 
But the most remarkable condition is seen in the distribution 
of the creatures of the deep sea, for here the temperature is nearly 
the same everywhere, being only slightly above the freezing point. 
Accordingly many of these animals range from Arctic to Antarctic, 
and from Atlantic to Pacific. : 
Many forms that live only in deep, cold water, south of Cape 
Cod come into the shallows on the Maine coast. 
