Tensas gazette. [volume] (St. Joseph, La.) 1886-current, 1915-10-22
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the slime pores and canals are greatly developed
and must exude large quantities of slime? Then
too, on deepsea expeditions. on favorable occa-
stonA as for instance, dark calm night, fishes
that have been brought to the surface and placed
IN water were seen to flash light from the ends
Of the tentacles or the phosphorescent pores.
precisely as we should have expected from
study Of these organs. Major Alcock in his
interesting volume "A Naturalist In Indian
Sets" mentions q specimen brought up from a
profound depth which "gimmered like a ghost
as II lay dead at the bottom of the pail of tur-
ht seawater. So that by inference. as well as
by actual observation. we must believe that what
vs call luminous organs in deepsea fishes emit
light into the darkness about them. In the case
OF fishes totally blind. the absence OF light is
compensated for by the development of enor-
nous antennaelike feelers. modified from fin
nys. SO that these fishes can feel their way.
IS it were. through the darkness
( The absence of light however entails another
important consequence Az In well known. no
plant life can exist in darkness. There is there
fore no vegetation Of any kind in the profound
depths Of the sea. The deep-sea fishes are. in
consequence. all carnivorous. the more powerful
ones seizng and devourng the weaker ones. II
is cold black world where might reigns su-
preme Many have enormous mouths, and for
midable teeth to insure holding the prey In
some forms the teeth are 80 large that the mouth
cannot be shut!
The temperature Of the water in the profound
depths Of the sea. is always low and near the
freezing point. This is true everywhere, even
at the equator. Undoubtedly this has an effect
upon the fishes. although it is not yet known
what It is. The amount of oxygen dissolved in
the water also. is much less than in water nearer
the surface. The breathing apparatus of the
deep-sea fishes is modified to suit their peculiar
conditions. The gill haments have become much
reduced in sze and in a number Of instances
some Of the gill arches bear no gill haments at
ALL The fishes are apparently adapted to q
much smaller oxygen supply than those living
in rivers in the shallow sea.
When we think of the vast diversity among
these fishes. the question arises: Are they all
representatives of a single family group that
has become specially adapted to life in the deep
sea: or do they belong to different families or
groups? One need hardly be an ichthyo sist
to answer this question. Even a cursory exam
ination Of the plates in a work on deep-sea
fishes will show that different types are repre-
sented. In fact. a great many families are in
cluded in the deep-sea fauna. There are sharks
and rays: salmonoids. herrings perches eels,
and representatives OF many other families We
can explain this heterogeneity among them in
this way We may imagine that fishes of many
different kinds in their search, so to speak for
the unoccupied corners Of the sea. found haven
in these deeper waters where they were free
from pursuit by their enemies. In the course of
time they migrated farther and farther into the
deep. a change in habits taking place pari passu
with the changes in structure. Having started
out with different organizations. and possessing
different degrees of variability. they became diff
ferentiated in diverse directions. that while
some developed enormous mouths powerful
teeth. or phosphorescent organs, others became
and partly or completely lost their
eyes Still others developed long feelers for
cropping their way through the darkness. Now
and again. however. fishes of separate groups
developed similar structures. that there are
many striking cases among deep-sea fishes Of
what the biologist calls "convergence." or paral-
elism
The museum has recently prepared for exhi-
bition q number Of typical deepsea fishes Ar
ranged in the form Of q group. The preparation
of this exhibit involved many technical dificul-
les. such as the modelling Of the fishes in trans
parent or translucent media, to represent them
Is glimmering or shining With litup "portholes-
experimenting was necessary to