'
FEEDING OF MARINE ANIMALS
213
resources.
This accumulation of reservé food aects
"
vital functions of the animal in.such a way as to lead to
_
the
appearance
of female characteristics, even to the
_'
production of eggs !
,
SYMBIOSIS
In a previous chapter we discussed the case of animals
which lived together, such as gall crabs in corals, and hermit
crabs in anemones or with .anemo‘nes growing on their
shells.
This mutual association has not only to do with
defence but with food,—thus the anemone in return for the
protection it aords the hermit crab is able to seize frag—
,
ments of food broken up by the crab, while in the more
extreme case of the pea, crab‘ which lives within muSsels
”
or similar bivalves or within the large sea squirts, the crab_
intercepts the food collected on the latticed feeding organs
of these animals, scOoping into its mouth strings of food
mixed with m‘ucus.
But there is a much more —intimate
form of association the object of which is also provision of
_
food for one or both of the parties concerned; » We may have
.'
two animals or an animal and a plant living in intimjate
union the one with the other .to their mutual advantage,
',
and often so dependent one
another that one or both
cannot exist if separated from the other.
_
This is the type
of aæociation' known as syinbiosis.
'
-
"
The commonest type of symbiosiS is the partnership
between an animal and minute,
yellow or brown
-
plants—single—celled A]gæ——which are'
taken
into
_
the
tissues of the animal in large numbers.
Many of the
.
simplest animals, the protozoa, especially the delicate
’
,
'
Radiolariahs, always contain these, as do some sponges,
'
and atworins.
animals are always associated
,
-
.
with a particular kind of alga which is called
Zoochlorella'
'
—
green and Zooxanthella if yellow.
The advantage to
.
FEEDING OF MARINE ANIMALS
213
resources.
This accumulation of reservé food aects
"
vital functions of the animal in.such a way as to lead to
_
the
appearance
of female characteristics, even to the
_'
production of eggs !
,
SYMBIOSIS
In a previous chapter we discussed the case of animals
which lived together, such as gall crabs in corals, and hermit
crabs in anemones or with .anemo‘nes growing on their
shells.
This mutual association has not only to do with
defence but with food,—thus the anemone in return for the
protection it aords the hermit crab is able to seize frag—
,
ments of food broken up by the crab, while in the more
extreme case of the pea, crab‘ which lives within muSsels
”
or similar bivalves or within the large sea squirts, the crab_
intercepts the food collected on the latticed feeding organs
of these animals, scOoping into its mouth strings of food
mixed with m‘ucus.
But there is a much more —intimate
form of association the object of which is also provision of
_
food for one or both of the parties concerned; » We may have
.'
two animals or an animal and a plant living in intimjate
union the one with the other .to their mutual advantage,
',
and often so dependent one
another that one or both
cannot exist if separated from the other.
_
This is the type
of aæociation' known as syinbiosis.
'
-
"
The commonest type of symbiosiS is the partnership
between an animal and minute,
yellow or brown
-
plants—single—celled A]gæ——which are'
taken
into
_
the
tissues of the animal in large numbers.
Many of the
.
simplest animals, the protozoa, especially the delicate
’
,
'
Radiolariahs, always contain these, as do some sponges,
'
and atworins.
animals are always associated
,
-
.
with a particular kind of alga which is called
Zoochlorella'
'
—
green and Zooxanthella if yellow.
The advantage to
.