2. The open-sea or pelagic haunt includes all the brightly illumined
surface waters beyond the shallow water of the shore area.
It is perhaps the easiest of all the haunts of life, for there is no
crowding, there is considerable uniformity, and an abundance of food for
animals is afforded by the inexhaustible floating "sea-meadows" of
microscopic Algæ. These are reincarnated in minute animals like the
open-sea crustaceans, which again are utilised by fishes, these in turn
making life possible for higher forms like carnivorous turtles and
toothed whales. It is quite possible that the open sea was the original
cradle of life and perhaps Professor Church is right in picturing a long
period of pelagic life before there was any sufficiently shallow water
to allow the floating plants to anchor. It is rather in favour of this
view that many shore animals such as crabs and starfishes, spend their
youthful stages in the relatively safe cradle of the open sea, and only
return to the more strenuous conditions of their birthplace after they
have gained considerable strength of body. It is probably safe to say
that the honour of being the original cradle of life lies between the
shore of the sea and the open sea.