“4
THE SEAS
extremely delicate and easily destroyed by the net ; others,
however, possess wonderfully designed skeletons made up
of little plates which may carry spines and wings, giving the
plants a beautiful appearance (Plate 4o)’.
Some of these
‘
peridinians are the cause of the colouredwat'er mentioned
above.
The Goniaulax
40 has been known"
to occur in such profusion as to colour the water red, and
another species has been reported to be so thick that when
they died and decayed they caused the death of great
numbers of sh.
'
There is yet another group of plankton plants kn0wn as
Coccospheres.
also are unicellular but are charac—
terized by the presence of numerous calcareous plates
embedded in the cell, the different shapes of which serve
as a means of identication of the numerous species.
These three groups, the Diatoms, the Perid—inians, and
the Coccospheres, are the most important constituents of the
drifting plant life; The Diatoms are most abundant in the
.colder waters of the temperate and polar seas, while the two
,
.
latter are characteristic of the Warm waters of tropical and
sub-tropical regions.
,
_
'
—These plants are at times extremely abundant; they
'
have often been reported to beso thick in the Baltic that
a thimbleful of water would contain more than a thousand
individuals.
Were it not for these countless myriads of
small plants we Can safely say that the great oceans and“
seas
of the world would be valùeless to us as reservoirs from
which to draw muchof our food in the form of sh and
_
other edible marine animals, for the small plants of the
plankton are indeed the pasturage of the sea.
They form
.
the food of millions of small animals living in the drifting
:
community on
animals prey.
On land, man '
and beast alike are ultimately dependent on the grass
herbs of the eld for food, the animals which feed on the