FEEDING OF MARINE ANIMALS
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vores, and those which feed indiscriminately upon any kind
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of food ; but owing to our lack of knowledge concerning the
food of many marine beasts, it is perhaps better to divide up
marine animals according to the method by which they
feed rather than the particular substances which they eat.
Thus we may divide animals into those-which possess the
means
for feeding on ne particles, on large masses or
living preÿ, and nally for sucking in uid food. To these
must be added the parasites which prey upon other animals
and those remarkable cases of intimate union between two
animals or between an animal and a plant, the two being
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entirely or partly dependent one upon the other, a condition
known as “
symbiosis,” from two Greek Words meaning
“
together
”
and “ life.”
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INVERTEBRATE ANIMALS LIVING ON FINE FOOD
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The animals which feed on microscopic plants and animals
or
on
ne particles in suspension in the sea are usually
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either sessile creatures attached to the ”bottom, animals
which cannot go in search of
but have to take what
they can from —the water which ows past them,-or else
they are small animals of the plankton.
Many of the
mechanisms with which they are provided for collecting
their nely— divided food are extremely complicated, and the
mode of feeding in some, of these animals is the most
elaborate foundinthe— animal kingdom.
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A very large number of these animals create a stre‘am of
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water by means of tiny, rapidly moving hairs, known as
“
cilia ”
or “
agella,” the food particles being sieved out
and Swallowed.
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The simplest meChanism of this type is
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found among ”the sp0nges whiCh are honeycombed with a
series of ne
through which water passes to be later
expelled by' a large central opening or “ osculum,” all food
particles in the water having been seized and absorbed