The flying-fish takes rank as one of the most conspicuous "wonders of
the sea," and in a tale essentially devoted to the great deep, it is a
subject deserving of more than a passing notice.
From the earliest periods of ocean travel, men have looked with
astonishment upon a phenomenon not only singular at first sight, but
which still remains unexplained, namely, a fish and a creature believed
to be formed only for dwelling under water, springing suddenly above the
surface, to the height of a two-storey house, and passing through the
air to the distance of a furlong, before falling back into its own
proper element!
It is no wonder that the sight should cause surprise to the most
indifferent observer, nor that it should have been long a theme of
speculation with the curious, and an interesting subject of
investigation to the naturalist.
As flying-fish but rarely make their appearance except in warm
latitudes, few people who have not voyaged to the tropics have had an
opportunity of seeing them in their flight. Very naturally, therefore,
it will be asked what kind of fish, that is, to what _species_ and what
_genus_ the flying-fish belong. Were there only one kind of these
curious creatures the answer would be easier. But not only are there
different species, but also different "genera" of fish endowed with the
faculty of flying, and which from the earliest times and in different
parts of the world have equally received this characteristic
appellation. A word or two about each sort must suffice.
First, then, there are two species belonging to the genus _Trigla_, or
the Gurnards, to which Monsieur La Cepede has given the name of
_Dactylopterus_.
One species is found in the Mediterranean, and individuals, from a foot
to fifteen inches in length, are often taken by the fishermen, and
brought to the markets of Malta, Sicily, and even to the city of Rome.
The other species of flying gurnard occur in the Indian Ocean and the
seas around China and Japan.
The true _flying-fish_, however, that is to say, those that are met with
in the great ocean, and most spoken of in books, and in the "yarns" of
the sailor, are altogether of a different kind from the gurnards. They
are not only different in genus, but in the family and even the order of
fishes. They are of the genus _Exocetus_, and in form and other
respects have a considerable resemblance to the common pike. There are
several species of them inhabiting different parts of the tropical seas;
and sometimes individuals, in the summer, have been seen as far north as
the coast of Cornwall in Europe, and on the banks of Newfoundland in
America. Their natural habitat, however, is in the warm latitudes of
the ocean; and only there are they met with in large "schools," and seen
with any frequency taking their aerial flight.
For a long time there was supposed to be only one, or at most two,
species of the _Exocetus_; but it is now certain there are several--
perhaps as many as half a dozen--distinct from each other. They are all
much alike in their habits,--differing only in size, colour, and such
like circumstances.
Naturalists disagree as to the character of their flight. Some assert
that it is only a leap, and this is the prevailing opinion. Their
reason for regarding it thus is, that while the fish is in the air there
cannot be observed any movement of the wings (pectoral fins); and,
moreover, after reaching the height to which it attains on its first
spring, it cannot afterwards rise higher, but gradually sinks lower till
it drops suddenly back into the water.
This reasoning is neither clear nor conclusive. A similar power of
suspending themselves in the air, without motion of the wings is
well-known to belong to many birds,--as the vulture, the albatross, the
petrels, and others. Besides, it is difficult to conceive of a leap
twenty feet high and two hundred yards long; for the flight of the
_Exocetus_ has been observed to be carried to this extent, and even
farther. It is probable that the movement partakes both of the nature
of leaping and flying: that it is first begun by a spring up out of the
water,--a power possessed by most other kinds of fish,--and that the
impulse thus obtained is continued by the spread fins acting on the air
after the fashion of parachutes. It is known that the fish can greatly
lighten the specific gravity of its body by the inflation of its
"swim-bladder," which, when perfectly extended, occupies nearly the
entire cavity of its abdomen. In addition to this, there is a membrane
in the mouth which can be inflated through the gills. These two
reservoirs are capable of containing a considerable volume of air; and
as the fish has the power of filling or emptying them at will, they no
doubt play an important part in the mechanism of its aerial movement.
One thing is certain, that the flying-fish can turn while in the air,--
that is, diverge slightly from the direction first taken; and this would
seem to argue a capacity something more than that of a mere spring or
leap. Besides, the wings make a perceptible noise,--a sort of
rustling,--often distinctly heard; and they have been seen to open and
close while the creature is in the air.
A shoal of flying-fish might easily be mistaken for a flock of white
birds, though their rapid movements, and the glistening sheen of their
scales--especially when the sun is shining--usually disclose their true
character. They are at all times a favourite spectacle, and with all
observers,--the old "salt" who has seen them a thousand times, and the
young sailor on his maiden voyage, who beholds them for the first time
in his life. Many an hour of _ennui_ occurring to the ship-traveller,
as he sits upon the poop, restlessly scanning the monotonous surface of
the sea, has been brought to a cheerful termination by the appearance of
a shoal of flying-fish suddenly sparkling up out of the bosom of the
deep.
The flying-fish appear to be the most persecuted of all creatures. It
is to avoid their enemies under water that they take _fin_ and mount
into the air; but the old proverb, "out of the frying-pan into the
fire," is but too applicable in their case, for in their endeavours to
escape from the jaws of dolphins, albicores, bonitos, and other petty
tyrants of the sea, they rush into the beaks of gannets, boobies,
albatrosses, and other petty tyrants of the sky.
Much sympathy has been felt--or at all events expressed--for these
pretty and apparently innocent little victims. But, alas! our sympathy
receives a sad shock, when it becomes known that the flying-fish is
himself one of the petty tyrants of the ocean,--being, like his near
congener, the pike, a most ruthless little destroyer and devourer of any
fish small enough to go down his gullet.
Besides the two _genera_ of flying-fish above described, there are
certain other marine animals which are gifted with a similar power of
sustaining themselves for some seconds in the air. They are often seen
in the Pacific and Indian oceans, rising out of the water in shoals,
just like the _Exoceti_: and, like them, endeavouring to escape from the
albicores and bonitos that incessantly pursue them. These creatures are
not fish in the true sense of the word, but "molluscs," of the genus
_Loligo_; and the name given to them by the whalers of the Pacific is
that of "Flying Squid."