Iron County register. [volume] (Ironton, Iron County, Mo.) 1867-1965, 1894-09-13
~ EvoLoT,oN OF FISHES
They <..--.s.. So. Among Hat:zs and
is~e:s IN Trorica. Waters.

n:g5 n seTer..t grouos OF - hes {xrssss
e ts>. dODi-,icrs ard rock co3" 70.
examples those specs which inkabii
| nor: her. tvaters have Lore vertebrate
| than hose wing in the tropics. Ger
| tain arctic houHSers, for example have
! sixty vert~brae; trUpieal founders have.
ON the average, thirty. The signifi-
canoe of this fact Is the problem at
Issue. In science it is assumed that all
facts have Significance else they would
| not exist. 1t becomes necessary. then,
to find out what the facts are in this
regard Going through the various
groups. of non-migratory marine fishes
we find that such relations are COM
| mon. In almost every group
the number of vertebrate grows
smaller as we approach the
equator, and grows larger again as
we pass into southern ATTITUDES It
would be tedious to try 30 prove this
by statistical tables. but the value Of
generalization in science depends on
such evidence. Suffice it to say that
taking an average netful OF fishes of
different kinds at different places along
the coast. the variation would be evil
dent. At Point Barrow or Cape Fare
well or North cape seineful OF fishes
would perhaps average eighty verte-
brae apiece. the body heightened to
make room for them; at Sitka or St
Johns Or Bergen. perhaps, sixty verte-
brae; at San Francisco or New York Or
St Malo. thirty-five; at Mazatian or
Pensacola or Naples, twenty-eight,
and at Panama or Havana or Sierra
Leone. twenty-five. Under the equa-
tor the usual number of vertebrate in
shore fishes is twentyfour: Outside the
tropics this number is the except on.
North of Cape Cod it is virtually I'M
known
The next question which arises is
whether we can find other conditions
that may affect these numbers. These
readily appear. Fresh water fishes
have IN general more vertebrate than
salt water fishes of the same group.
Deep sea fishes have more vertebrae
than fishes of shallow waters. Pelagic
fishes and free-swimming fishes have
more than those which live along the
shores, and more than localized or nom
migratory forms. The extinct fishes of
earlier geological periods had more
vertebrae than the corresponding mod
ern forms which are considered as their
descendants. To each of these gener-
a1iZations there are occasional partial
exceptions. but not such as to invali-
date the rule. All these effects should
be referable to the same group of
causes. They may, in fact, be COM
bined in one statement. All other
fishes have larger number of verte
brae than the marine fishes of the
tropics. The cause of the reduc-
ton in the number of vertebrae
must, therefore. be sought in condi-
tions peculiar to the tropical seas. If
the retention of the primitive large
number is in any case phase of de-
generation. the cause of such degener-
alton must be sought in the colder seas,
in the rive and in oceanic abysses
What have these waters in common
that the coral reefs. rocky islands and
tide pools of the tropics have not? In
this connection we are to remember
that the fewer vertebrae indicates gen.
orally the higher rank. When verte-
brae are few in number, as a rule each
one is larger. Its structure is more
complicated, its appendages are larger
and more useful, and the fins with
which it is connected are better devel-
oped. In other words, the tropical fish
is more intensely and compactly fish,
especially for that of fish that stays
at home. In my view, the reduction
in number and increase of i'm
portance of the individual verte-
brae are simply part of this work of
making a better fish. Not a better
fish for mans purpOSe-fOr Nature does
not care a straw for mans purpose
but a better fish for the purposes of a
fish. The competition in the struggle
for existence is the essential cause of
the change. In the center of competition
no species can afford to be handicapped
by weak backbone and a redundant
vertebrate. Those who are thus weight
ed down can not hold their own. They
must change or perish.
The influence of cold, darkness. mo-
notony and isolation is to limit the
struggle for existence, and therefore
to prevent its changes, persevering
through the conservation of hereditv
the more remote ancestral conditions,
even though they carry with them dis
advantages and deficiencies. The con-
ditions most favorable to fish life are
ical seas. About the coral reefs is the
center of fish competition. A coral
archipelago is the Paris of fishes. In
such regions is the greatest variety of
surroundings. and therefore the great
est number of possible adjustments.
The struggle is between fish and fish.
not between fishes and hard conditions
of life. No form is excluded from the
competition Cold. darkness and foul
water do not shut out competitors, nor
does any evil influence sap the strength.
The heat Of the tropics does not make
the water hot. It is never sultry nor
laden with malaria. The influence of
tropical heat on land animals is often
to destroy vitality and check self-activi-
ty. 1t Is not SO in the sea. From condi-
lions otherwise favorable in arctic re-
gions the ma jority of competitors are ex-
Guided by their inability to bear the
cold. River life is life in isolation. To
aquatic animals river life has the same
limitations that inland life has to the
animals of the land. The oceanic
islands are behind the continents in
the process of evolution. In like man.
ner the rivers are ages behind the seas.
Therefore the influences which serve
tend to rid the fish of every character
or structure it can not ''be in its bust |
ness are most effective along the
shores of the tropics. One phase OF
this Is the reduction in numbers OF
vertebrse. or. more accurately. the in
crease of stress on each individual bone