DRIFTING LIFE
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grass being 'eaten by m‘an ; so also in the sea, the ultimate
food supply is to Î be found -in the drifting microSc0pic
plants. But, whereas on land the plants are substantial
and can .be directly eaten by large animals, in the sea they
are minute and are rst eaten
small dritting animals,
which are in turn swallowed by larger creatures, and So on
until, eventuay, the sh forms food for man.
In fact
certain chemical cohstituents of our food have been traced
to these tiny plants. To most the word “ vitamin ? ’ is
well—known.
It is the name given to Certain chemical
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bodies, which, although present in minute quantities only
in our food; appear to be essential to our health and well—.
being.
Their abSence is thought to give rise to such diseases -
as
scurvy ;
and erce controversy has raged over the
desirability of eating white or wholemeal bread. Cod—liver
oil also contains a certain vitamin which is thought to be
partly responsible for its great medicinal value. The
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presence of this vitamin has been traœd from the liver of
the cod to the insides of the capelin (JlÆalloiusvülosus), a —
little shthat forms a large portion of the Cod’s food, and
the swarms of which bring the cod together in vast shoals
,
on the-Nve0undland banks.
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From the capelin it has been
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traced to the minute animals on which it feeds, and so to the
diatoms jWhiCh nouriSh them.
It is in. these "little plants——
the diatoms—that the vitamins are made.
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PLANKTÔN1ANIMALS
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We have mentioned above that the drifting plants form
the chief food of the small animals of the same Community—;
Of what is this animal population chiey composed ?
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Actually almost every group of the invertebrate- animal
kingdomhas representatives in the plankton.
,
In addition;
the-young of‘iädany kinds of sh live for a sh0rter.or longer
,
periode free, drting existence; .-But off tar. thegreateSt
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