AQUATIC ARCHERY—THE ANGLER-FISH AND THE CUTTLEFISH—INSECT
ARTILLERY—EELS THAT GIVE ELECTRIC SHOCKS.
In the ant-lion that we have just been talking about it might be
thought that the summit of strategy, as employed by one animal to prey
upon another, had been reached. Inasmuch as the archer-fish uses only
the weapon with which Nature has provided it, and does not add to its
efficacy by any artifice other than that of simple stalking—as it
constructs nothing, in a word—perhaps its instinct is not really so
extraordinary as that of the insect in question. But there is something
so bizarre in it, so striking to the imagination—the idea is so pretty
and quaint—that when one first reads about it—for only the far-travelled
few are lucky enough to see it—it impresses one even more.
This wonderful little fish—for it is not more than six or seven inches
long—is a native of Java and other parts of the Indian Archipelago. It
is of a curious appearance, the body being much compressed—as though it
had been flattened out sideways—and its dorsal fin is spiny, like that
of the perch, but set much further back, so that it almost touches the
tail. The head is pointed, with the lower jaw or lip projecting beyond
the upper one, but the most distinctive feature is the eye, which is
extremely large and round, so that it imparts a look of strange staring
surprise, to which, no doubt, the creature is a stranger. The surprise
is not on the part of the fish, but on that of any insect of moderate
dimensions which may happen to be resting on a leaf or flower overhanging
the water, and not more than four or five feet above it. The archer-fish,
observing it there, swims as near as it can underneath it, and then,
approaching its mouth to the surface of the stream, whilst it hangs
stationary with pulsating fins, squirts, all at once, out of it a little
shower of water-drops, which, striking the insect—bee, fly, moth, or
grasshopper—knocks it off into the river. As it falls, the successful
marksman lowers its head, and poising itself for a moment, after a few
backward strokes, darts on the floating spoil, and devours it.
The aim is remarkably sure, nor is the feat a slight one, seeing that
the drops are projected to some eight or ten times the length of the
fish. By this curious sort of archery, or, rather, water-fire—for the
drops fly out, as from the muzzle of a little live gun—an easy living
is procurable. _Toxotes jaculator_ (that is its Latin name) is not,
like other fish, dependent on the chance of an accidental immersion.
Swimming quietly along, under banks heavy with tropical foliage, it
peers hopefully up into that flowery firmament, from which its manna
is to fall. The keen eye, armed with a sight in proportion to its
uncommon size, examines each leaf, each petal, each bending stem or
pendent, swaying creeper—the fringe of a world unknown beyond it—and
carefully estimates the distance at which an insect buzzes or settles.
Anything beyond six feet or so is a bright, particular star, which it
were hopeless to attempt—but within that distance the fairest things are
attainable; up spurts the glistening shower and down with it, like Iris
on her rainbow, the radiant being comes. It is a pretty, clean sort of
shooting, without noise, wounds, or blood, much superior to our own.
Several little fishes, besides the one to which in especial the name
of archer has been given, practise this curious and, except for
themselves, unique art. But they are all nearly related—all belong to
the Acanthopterigious family of Squamipennes or Chætodontidæ—for those
are the sort of names that they call them in scientific works. One of
these other kinds is a favourite with the Chinese in Java, who keep it in
jars, and feed it with flies or other insects, which they place on their
edges for the little archers to knock off. Possibly there may be some
other animals, besides these fishes, which obtain their prey by shooting
water at it, but I do not, myself, know of any before we come to man.
The Australian savages chase bees to their hives, by encumbering their
wings with cotton or something similar, and they first catch the bees by
filling their mouths with water, and squirting it out over them. Thus we
find in man the nearest approach to the archer-fish, and it is to him,
too, that we must look for a parallel, artificially brought about, to
the natural art of another of the great fish family, viz. the angler or
sea-devil.
This wonderfully provided creature has an enormous head, on the top of
which grow three long filaments, two forward, and close together, and
the third a good deal farther back. The front filament of all, bends
forward and seems to dangle from its end, in front of the angler’s huge
mouth, a little silvery tuft, or piece, of something, so that the whole
has a wonderful resemblance to a fishing-rod and line, with a baited hook
at the end of it. The owner of this curious arrangement lies along the
bottom of the sea, near the shore, almost hidden in the sand, and when a
small fish, attracted by the shining appendage, comes to nibble at it,
makes a rush and engulfs, rather than seizes, it in its cavernous jaws.
The object, which thus plays the part of a bait, is really an expansion
of the filament itself. The creature is thus provided with a natural
fishing-rod, which, however, is designed only to attract the prey about
the bait, and not to hook and haul it up. In this way the game is lured
within the angler’s reach, and the actual catching of it is done by the
mouth, in the ordinary way.
In addition to this natural ruse, or, rather, as a supplement to it, the
angler-fish is said purposely to stir up the sand, so as to dislodge
the marine worms or other creatures which dwell there, which then float
about in the water, so that they play the same part that ground-bait
does when thrown in around the float. The discoloured water, full of
living creatures or inorganic particles, brings numbers of fish there,
to feed on them, whilst the silvery filament swaying and dancing in the
middle of the cloud, becomes to each one the more particular attraction.
The angler-fish is fairly common, about our own shores. It grows to a
length of some three or four feet, and appears to consist of but head
and tail—so huge is the size of the former, into which the body seems
to be absorbed. The wide mouth is set with sharp teeth, and suggests,
when opened, a ravenous voracity, which is, indeed, the angler’s chief
characteristic.
As has been remarked, the principles on which the two foregoing artifices
are based, have been applied by man, in an essentially similar manner, to
meet the exigencies of his own affairs, but I am not sure whether this
is equally the case in regard to another and well-known device which is
employed by the cuttlefish. This creature, which, as will be seen in a
later chapter, sometimes grows to an enormous size, though popularly
called a fish, is not really one. It is a mollusc, and belongs to the
most perfectly organised family of that extensive order of beings—viz. to
the cephalopods. This is a word which, in English, means the head-foots,
and as a descriptive term it is properly employed, since the limbs of
the cuttlefish—which can be used either as arms or feet—grow from the
orifice of the mouth, and so may be considered, equally with the latter,
as belonging to the head. These limbs are the well-known tentacles, and
in number may be either eight—which makes their possessor an octopod—or
ten, by which it becomes entitled to the rank of a decapod. In the latter
case, two of these organs have become specially modified, being much
longer than the other ones, and enlarged at their ends, upon which alone
the suckers are situated. On the remaining eight—or on all the eight in
the case of the octopods—the suckers run along the whole length of the
limb, from base to tip, being disposed in two or more rows, upon the
inner surface of it. They are circular discs, and if we wish to picture
them and the office which they perform, we cannot do better than imagine
ourselves with eight long lips, each of which is provided with so many
little miniature mouths that can suck very hard, but not bite or swallow.
In the centre of this wonderful lip arrangement is our big mouth—the real
one—only slightly changed, so that the teeth are represented by a great
horny beak, shaped like a parrot’s and quite as effective. As for the
rest of us—to continue the illustration—all our four limbs have gone, so
that there is only our body, which is now like a large sack or purse.
Changed in this way, we can no longer lead the life that we have been
accustomed to. We live in the sea, now, and are usually at the bottom of
it, holding on to rocks or stones with some of our sucking tentacles,
and often getting our soft, unarmed bodies into holes and crevices, the
better to protect them. Our long lip-arms are always waving about in the
water, and when we are hungry we throw them round anything that we care
about eating, suck on to it with all our little mouths, and bite and
swallow it with our big one. We need not go very far to supply our wants.
Our waving tentacles look very like the seaweeds that we live amongst, so
that fish, crabs, starfish, and all sorts of other living creatures are
constantly swimming up against us, and when we like them and are hungry,
we always treat them in this way. The shell of the crab must be hard that
we cannot crack with our great parrot beak, and the fish must be clever
that can avoid our embraces, since the faster it goes the faster we go
with it. We hug it till it stops, and then eat it—we do not understand
letting go.
Such and so strange a creature is the cuttlefish, but perhaps the
strangest, or at least the most interesting, thing about it, is that
device that it practises, and which I began by alluding to. In its body
there is a sort of bag, containing a fluid from which ink and the pigment
known as sepia are prepared, and which is of a deep brown colour. This
bag or gland has an opening near the end of the body, through which the
fluid can be ejected into the sea, which then becomes discoloured. There
is another opening near the creature’s mouth, and through this water
can be expelled by it, in the same way but with greater violence. When,
therefore, the cuttlefish is alarmed, and wishes to “lie low,” it spurts
out the water with such force that its body flies backwards, and, at the
same time, empties the contents of its ink-bag, thus making for itself a
cloudy sanctuary, into the midst of which it disappears. After a time the
water clears again, but the cuttlefish, in all probability, is nowhere to
be seen.
It would be difficult to think of anything more _rusé_ than this, within
the limits of the animal kingdom; but certain beetles play a trick which
is quite as ingenious, and perhaps even more remarkable. These are
the bombardier beetles, as they are very appropriately called, little
creatures not more than the third of an inch long, and with nothing very
remarkable about their appearance. When, however, they are pursued by
some larger beetle, or other insect, of carnivorous habits, all at once,
just as they seem on the point of being overtaken, they fire off a gun,
and the pursuer rolls head over heels. That, at least, is what it looks
like. There is smoke and a sudden bang that one can just hear, and it
seems as if the big beetle had been shot. What really happens is this:
the bombardier beetle discharges from a gland in the posterior portion
of the abdomen, with which it is furnished, a very acid fluid, which, by
a chemical process, when it meets the air, volatilises into smoke, with
a slight explosion. Whether it is the explosion or the acid properties
of the fluid, or some disagreeable smell it has, which upsets the
beetle that is in pursuit, I am not quite sure. If the latter, then the
bombardier beetle is something like the skunk, an animal we shall have
something to say about later on, but I think it is the actual explosion,
which, though weaker, acts in the same way as an explosion of gunpowder
does. Whatever may be the reason, the effect is very remarkable, and
in this sudden discharge by the little beetle, with the consequent
instantaneous collapse of its enemy, we see one of the most ingenious
of Nature’s devices for protecting her little children against her big
ones. To look at, it is perhaps the most wonderful of all, for it is just
like real artillery—smoke, an explosion, and then over rolls somebody—a
regular battlefield.
Angling, dyeing, archery, artillery—where will it end? If it does
not stop soon it will get to electricity; and, sure enough, in the
gymnotus—a large eel that inhabits the rivers of Brazil and Guiana—we
have a creature with an electric battery inside it, with which it can
deliver shocks so powerful, that they are capable of killing a man or
stunning a horse. I do not know if the alligators that live in the
same rivers with it—for instance, the Orinoco—ever attack this eel. It
would be an interesting thing to see one do so, but the probability is
that the alligator knows what the gymnotus is, and never touches it
except by accident. This, however, must sometimes occur, but what the
result would be in the case of so sluggish a reptile, I cannot say. Of
course, it is only the big eels that give such severe shocks as these.
The gymnotus grows to six feet in length, and one of this size must be
a more dangerous creature, if one happens to run up against it, than a
man-eating tiger or a rogue elephant. Its habits are sluggish, as one
might expect, for it has no need to get out of the way of anything, and
it is a good deal easier for it to kill its prey by lying still in the
mud, and allowing it to touch it, than it would be to pursue a fish, for
instance, and rub up against it in the water.
To receive the shock it is necessary that the creature, whatever it may
be—in most cases, probably, a fish—should touch the eel’s body in two
places, for otherwise the electric circuit will not be completed, and
there will be no discharge. Merely to poke the eel, therefore, with one
finger would do one no harm, whereas to catch hold of a large one might
even cause death. Yet in spite of the dangerous power it possesses,
the torpedo is eaten by the natives of the countries in which it is
found, for it is fat and succulent, and its electric battery, if once
it can be got rid of, does not affect its taste, which is excellent.
Once caught, this is not a difficult thing to do. It can be cut out,
though care must be taken in the way above-mentioned, since the shock
can be communicated not only by a direct seizure of the creature, but
indirectly through any connecting substance held in the hand. But how
are the eels to be caught? The method employed by the Indians is to make
them exhaust their batteries by delivering a series of shocks, after
which they remain for a long time innocuous, till re-stored with the
electric energy. When, therefore, any large shallow pool is discovered,
in which gymnoti are likely to be lying—such being often produced by the
overflowing of rivers and subsequent withdrawal of their waters—a troop
of half-wild horses are collected about it, and then, with cries and
blows, urged to enter. A wild and horrible scene of confusion instantly
ensues. The alarmed eels dart hither and thither amongst the legs of the
horses, discharging their batteries, and the horses, when struck, leap
into the air, and, if the shock has been violent, fall down stunned,
amongst the rest. Others, less injured, but mad with pain and terror,
lash out with their heels, or gallop wildly about, no longer avoiding
their fellows, and seeming to have lost the sense of direction. Dashing
together, one horse is flung down by another—others fall over them—they
lie struggling in heaps. Many break back, or reach the further shore,
but each time that they do so, and strive to leave the pool, they are
driven into it again by the Indians, and shock after shock continues to
be poured in amongst them. Each one, however, is weaker than the last,
till, at length, no more effect is produced, and the scene, though still
wild and disorderly, becomes partially relieved of its horrors. Then, and
not till then, are the terrified animals—all those, that is to say, that
are capable of doing so—allowed to leave their inferno, after which the
Indians enter it, and secure the now powerless eels, many of which have
been more or less injured by the trampling of the horses’ hoofs. Such is
the account given by Humboldt, which was given to him by the Indians.
It is right to add that it has not yet been confirmed, so that many now
hold it to be untrue, and think that the great naturalist and traveller
must have been imposed upon. One professor, who writes very learnedly of
the gymnotus, and other electric fishes—for there are some other ones—is
so sure of this, that he thinks it high time this story of Humboldt’s
were forgotten. Well, I tried to forget it, but I found it was too
picturesque. So I have remembered it, and forgotten the professor’s own
treatise, instead—which was much the easier thing to do.