FISHES OF THE DEEP-SEA 
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 these peculiar 
conditions. The gill filaments have 
become much reduced in size, and in a 
number of instances some of the gill- 
arches bear no gill filaments at all. The 
fishes are apparently adapted to a much 
smaller oxygen supply than those living 
in rivers or 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, or group that has become spe- 
cially adapted to life in the deep sea; 
or do they belong to different families 
or groups? One need hardly be an 
ichthyologist to answer this question. 
Even a cursory examination of the plates 
in a work on deep-sea fishes will show 
that different types are represented. In 
fact, a great many families are included 
in the deep-sea fauna. There are sharks 
and rays; salmonoids, herrings, perches, 
eels, and representatives of many other 
families. We can explain this hetero- 
geneity among them in this way. We 
may imagine that fishes of many differ- 
ent kinds in their search, so to speak, 
for the unoccupied corners of the sea, 
found a 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 organi- 
zations, and possessing different degrees 
of variability, they became differen- 
tiated in diverse directions, so that while 
some developed enormous mouths, pow- 
251 
erful teeth, or phosphorescent organs, 
others became bottom-living and partly 
or completely lost their eyes. Still 
others developed long feelers for groping 
their way through the darkness. Now 
and again however, fishes of separate 
groups developed similar structures, 
so that there are many striking cases 
among deep-sea fishes of what the 
biologist calls “convergence,” or paral- 
lelism. 
The Museum has recently prepared 
for exhibition a number of typical deep- 
sea fishes arranged in the form of a 
group. The preparation of this exhibit 
involved many technical difficulties, 
such as the modeling of the fishes in 
transparent or translucent media, to 
represent them as glimmering or shining 
with lit-up “portholes.” Considerable 
experimenting was necessary to accom- 
plish this group, but all the difficulties 
were overcome, thanks to the ingenuity 
and perseverance of Mr. F. F. Horter of 
the Museum’s taxidermist staff. The 
group, as it is now installed, represents 
ten types of deep-sea fishes. It is not, 
of course, a group in the sense of the 
habitat groups displayed in the Museum; 
it is not a section, so to speak, taken 
from nature and transplanted to the 
Museum. In nature so many deep-sea 
fishes are not to be found in so small a 
space. What the group represents is a 
number of fishes which are in nature 
scattered over a vast area and through a 
great height of water, here brought 
together for museum purposes into a few 
square feet of space. Each fish is re- 
produced accurately with its phosphor- 
escent pores and tentacles as these are 
known to exist. With one or two ex- 
ceptions they are enlarged several times, 
as the fishes themselves are very small. 
And since it is known that the phos- 
phorescent organs do not glow with a 
steady light, the illumination of the 
