FISH.
ALTHOUGH we here pass into the sub-kingdom of animals the intelligence
of which immeasurably surpasses that of the other sub-kingdoms, it is
remarkable that these lowest representatives of the higher group are
psychologically inferior to some of the higher members of the lower
groups. Neither in its instincts nor in general intelligence can any
fish be compared with an ant or a bee--a fact which shows how slightly a
psychological classification of animals depends upon zoological
affinity, or even morphological organisation. For although a highly
competent authority, namely Van Baer, has said that a bee is as highly
organised an animal as a fish, though on a different type,[110] no one
would be found to assert that an ant or a bee is so much more highly
organised than a fish as its higher intelligence would require,
supposing degrees of intelligence to stand in necessary relation to
degree of organic development. And this consideration is not materially
altered if, instead of regarding the whole organism, we look to the
nervous system alone. There is no doubt that the cerebral hemispheres of
a fish, although small as compared with these organs in the higher
Vertebrata, are, bulk for bulk, enormous as compared with the
oesophageal ganglia or 'brain' of an insect; while the disproportion
becomes still greater if the cerebral hemispheres of a fish are compared
with their supposed analogues in the brain of an ant, viz., the
pedunculated and convoluted lobes which surmount the cephalic ganglion.
But here the relative smallness of the ant as a whole must be taken into
consideration, and also the fact that its brain is relatively much more
massive as well as more highly organised than that which occurs in any
other order of invertebrated animals, except, perhaps, the octopus and
his allies. Therefore, although the brain of a fish is formed upon a
type which by increase of size and complexity is destined in function
far to eclipse all other types of nerve-centre, we have to observe that
in its lowest stage of evolution as presented to science in the fishes,
this type is functionally inferior to the invertebrate type, where this
reaches its highest stage of evolution in the Hymenoptera.
_Emotions._
Fish display emotions of fear, pugnacity; social, sexual, and parental
feelings; anger, jealousy, play, and curiosity. So far the class of
emotions is the same as that with which we have met in ants, and
corresponds with that which is distinctive of the psychology of a child
about four months old. I have not, however, any evidence of sympathy,
which would be required to make the list of emotions identical; but
sympathy may nevertheless be present.
Fear and pugnacity are too apparent in fish to require special proof.
The social or gregarious feelings are strongly shown by the numberless
species which swim in shoals, the sexual feelings are proved by
courtships, and the parental by those species which build nests and
guard their young. Schneider saw several species of fish at the Naples
Aquarium protecting their eggs. In one case the male mounted guard over
a rock where the eggs were deposited, and swam with open mouth against
intruders. The following accounts of the nidification of certain species
of fish show that the parental instincts are not unlike those which
obtain in birds, and are comparable in point of strength with the same
instincts as they occur in ants, bees, and spiders.
Agassiz remarks[111] that while examining the marine
products of the Sargasso Sea, Mr. Mansfield picked up
and brought to him a round mass of sargassum, about
the size of the two fists placed together. The whole
consisted, to all appearance, of nothing but
gulf-weed, the branches and leaves of which were,
however, evidently knit together, and not merely
balled into a roundish mass. The elastic threads which
held the gulf-weed together were beaded at intervals,
sometimes two or three beads being close together, or
a branch of them hanging from the cluster of threads.
This nest was full of eggs scattered throughout the
mass, and not placed together in a cavity. It was
evidently the work of the _Chironectes_. This rocking
fish-cradle is carried along as an undying arbour,
affording at the same time protection and afterwards
food for its living freight. It is suggested that the
fish must have used their peculiar pectoral fins when
constructing this elaborate nest.
The well-known tinker or ten-spined stickleback
(_Gasterosteus pungitius_) is one of our indigenous
fish which constructs a nest. On May 1, 1864, a
male[112] was placed in a well-established aquarium of
moderate size, to which, after three days, two ripe
females were added. Their presence at once roused him
into activity, and he soon began to build a nest of
bits of dirt and dead fibre, and of growing confervoid
filaments, upon a jutting point of rock among some
interlacing branches of _Myriophyllum spicatum_--all
the time, however, frequently interrupting his labours
to pay his addresses to the females. This was done in
most vigorous fashion, he swimming, by a series of
little jerks, near and about the female, even pushing
against her with open mouth, but usually not biting.
After a little coquetting she responds and follows
him, swimming just above him as he leads the way to
the nest. When there, the male commences to flirt--he
seems unaware of its situation, will not swim to the
right spot, and the female, after a few ineffectual
attempts to find the proper passage into it, turns
tail to swim away, but is then viciously pursued by
the male. When he first courts the female, if she, not
being ready, does not soon respond, he seems quickly
to lose his temper, and, attacking her with great
apparent fury, drives her to seek shelter in some
crevice or dark corner. The coquetting of the male
near the nest, which seems due to the fact that he
really has not quite finished it, at length terminates
by his pushing his head well into the entrance of the
nest, while the female closely follows him, placing
herself above him, and apparently much excited. As he
withdraws she passes into the nest, and pushes quite
through it, after a very brief delay, during which she
deposits her ova. The male now fertilises the eggs,
and drives the female away to a safe distance; then,
after patting down the nest, he proceeds in search of
another female. The nest is built and the ova
deposited in about twenty-four hours. The male
continued to watch it day and night, and during the
light hours he also continually added to the nest.
The marine fifteen-spined stickleback (_Gasterosteus
spinachia_) affords another instance of
nest-constructing fishes. The places selected for
their nests are usually harbours, or some sheltered
spots to where pure sea water reaches. The fish either
find growing, or even collect some of the softer kinds
of green or red seaweed, and join them with so much of
the coralline tufts (_Janiæ_) growing on the rock as
will serve the purpose of affording firmness to the
structure, and constitute a pear-shaped mass five or
six inches long, and about as stout as a man's fist. A
thread, which is elastic and resembles silk, is
employed for the purpose of binding the materials
together: under a magnifier it appears to consist of
several strands connected by a gluey substance, which
hardens by exposure to the water.[113]
M. Carbonnier, who has studied the habits of the
Chinese butterfly-fish (_Macropodus_) in his private
aquarium in Paris, where he had some in confinement,
observed that the male constructs a nest of froth of
considerable size, 15 to 18 centimetres horizontal
diameter, and 10 to 12 high. He prepares the bubbles
in the air (which he sucks in and then expels),
strengthening them with mucous matter from his mouth,
and brings them into the nest. Sometimes the buccal
secretion will fail him, whereupon he goes to the
bottom in search of confervæ, which he sucks and bites
for a little in order to stimulate the act of
secretion. The nest prepared, the female is induced to
enter. Not less curious is the way in which the male
brings the eggs from the bottom into the nest. He
appears unable to carry them up in his mouth; instead
of this, he first swallows an abundant supply of air,
then descending, he places himself beneath the eggs,
and suddenly, by a violent contraction of the muscles
in the interior of his mouth and pharynx, he exhales
the air which he had accumulated by the gills. This
air, finely divided by the lamellæ and fringes of the
gills, escapes in the form of two jets of veritable
gaseous powder, which envelopes the eggs and raises
them to the surface. In this manoeuvre the
_Macropodus_ entirely disappeared in a kind of
air-mist, and when this had dissipated he reappeared
with a multitude of air-bubbles like little pearls
clinging all over his body.[1]
Again, in detailing Mr. Baker's observations on the three-spined
stickleback, published in the Philosophical Transactions, this author
says:--
It has been remarked that after the deposition of the
eggs the nest was opened more to the action of the
water, and the vibratory motion of the body of the
male fish, hovering over its surface, caused a current
of water to be propelled across the surface of the
ova, which action was repeated almost continuously.
After about ten days the nest was destroyed and the
materials removed; and now were seen the minute fry
fluttering upwards here and there, by a movement half
swimming, half leaping, and then falling rapidly again
upon or between the clear pebbles of the shingle
bottom. This arose from their having the remainder of
the yelk still attached to their body, which, acting
as a weight, caused them to sink the moment the
swimming effort had ceased. Around, across, and in
every direction the male fish, as the guardian,
continually moved. Now his labours became more
arduous, and his vigilance was taxed to the utmost
extreme, for the other fish (two tench and a gold
carp), some twenty times larger than himself, as soon
as they perceived the young fry in motion,
continuously used their utmost endeavours to snap them
up. The courage of the little stickleback was now put
to its severest test; but, nothing daunted, he drove
them all off, seizing their fins and striking with all
his strength at their heads and at their eyes. His
care of the young brood when encumbered with the yelk
was very extraordinary; and as this was gradually
absorbed and they gained strength, their attempts to
swim carried them to a greater distance from the
parent fish; his vigilance, however, seemed
everywhere, and if they rose by the action of their
fins above a certain height from the shingle bottom,
or flitted beyond a given distance from the nest, they
were immediately seized in his mouth, brought back,
and gently puffed or jetted into their place again.
The same care of the young, bringing them back to then
nest up till about the sixth day after hatching, has
been remarked by Dr. Ransom in the ten-spined
stickleback (_G. pungitius_).[114]
The well-known habit of the lophobranchiate fish, of incubating their
eggs in their pouches, also displays highly elaborated parental
feeling.[115] M. Risso says that when the young of the pipe-fish are
hatched out, the parents show them marked attachment, and that the pouch
then serves them as a place of shelter or retreat from danger.[116]
M. Carbonnier has recorded how the male of the
curiously grotesque telescope-fish, a variety of
_Carassius auratus_ (Linn.), acts as accoucheur to the
female. Three males pursued one female which was heavy
with spawn, and rolled her like a ball upon the ground
for a distance of several metres, and continued this
process without rest or relaxation for two days, until
the exhausted female, who had been unable to recover
her equilibrium for a moment, had at last evacuated
all her ova.[117]
That adult fish are capable of feeling affection for
one another would seem to be well established: thus
Jesse relates how he once captured a female pike
(_Esox lucius_) during the breeding season, and that
nothing could drive away the male from the spot at
which he had perceived his partner slowly disappear,
and whom he had followed to the edge of the water.
Mr. Arderon[118] gave an account of how he tamed a dace,
which would lie close to the glass watching its
master; and subsequently how he kept two ruffs
(_Acerina cernua_) in an aquarium, where they became
very much attached to one another. He gave one away,
when the other became so miserable that it would not
eat, and this continued for nearly three weeks.
Fearing his remaining fish might die, he sent for its
former companion, and on the two meeting they became
quite happy again. Jesse gives a similar account of
two gold carp.[119]
Anger is strikingly shown by many fish, and notoriously by sticklebacks
when their territory is invaded by a neighbour. These animals display a
strange instinct of appropriating to themselves a certain part of the
tank in which they may be confined, and furiously attacking any other
stickleback which may presume to cross the imaginary frontier. Under
such circumstances of provocation I have seen the whole animal change
colour, and, darting at the trespasser, show rage and fury in every
movement. Of course, here, as elsewhere, it is impossible to be sure how
far apparent expression of an emotion is due to the presence of that
mental state which we recognise as the emotion in ourselves; but still
the best guide we have to follow is that of apparent expression.
Following this principle, we are also entitled to attribute to fish the
emotions conducive to play; for nothing can well be more expressive of
sportive glee than many of their movements. As for jealousy, the fights
of many male fish for the possession of females constitutes evidence of
emotion which would be called by this name in the higher animals.
Schneider, in his recent work already often quoted, says that he has
observed a male fish (_Labrus_) show jealousy only towards other
individual males of his own species--chasing these away from the
neighbourhood of his female, but not objecting to the approach of fish
of other species.
Curiosity is shown by the readiness, or even eagerness, with which fish
will approach to examine any unfamiliar object. So much is this the case
that fishermen, like hunters, sometimes trade upon this faculty:--
And the fisher, with his lamp
And spear, about the low rocks damp
Crept, and struck the fish which came
To worship the delusive flame.[120]
Stephenson, the engineer, on sinking lighted lanterns in the water, also
found that fish were attracted to them.[121]
_Special Habits._
As curious instances of special instincts in fish we may notice the
well-known habit of the angler (_Lophius piscator_), which conceals
itself in mud and seaweed, while waving in the water certain filaments
with which it is provided above its snout. Other fish, attracted by
these moving objects, approach, and are thereupon seized by the angler.
We must also allude to the _Chelmon rostratus_, which shoots its prey by
means of a drop of water projected from the mouth with considerable
force and unerring aim. The mark thus shot at is always some small
object, such as a fly, at rest above the surface of the water, so that
when suddenly hit it falls into the water.[122] This remarkable instinct
can only, I think, have originated as a primordially intentional
adjustment, and as such shows a high degree of intelligence on the part
of these fishes' ancestors. Moreover, the wonderful co-ordination of
sight and muscular movements required to judge the distance, to make due
allowance for refraction, and to aim correctly, shows that the existing
representatives are not unworthy of their ancestors.
Several species of fish in different parts of the world have the habit
of quitting pools which are about to dry up, and taking excursions
across country in search of more abundant water. Eels have this habit,
and perform their migrations by night. Dr. Hancock, in the 'Zoological
Journal,' gives an account of a species of _Doras_, the individuals of
which are about a foot in length, and travel by night in large shoals,
or 'droves,' when thus searching for water. A strong serrated arm
constitutes the first ray of the pectoral fin; and, using this as a kind
of foot, the animal pushes itself forward by means of its tail, thus
moving nearly as fast as a man can walk. Another migrating fish
(_Hydrargzra_) was found by thousands in the fresh waters of Carolina by
Bosc. It travels by leaps, and, according to Bosc, always directs itself
towards the nearest water, although he purposely placed them so that
they could not see it.
But perhaps the strangest among this class of habits is that of the
climbing perch (_Perca scandens_), first discovered by Daldorff in
Tranquebar; for this animal not only creeps over land, but even climbs
the fan palm in search of certain Crustacea which form its food. In
climbing it uses its open gill-covers as hands wherewith to suspend
itself, while it deflects its tail laterally upwards so as to bring to
bear upon the bark certain little spines with which its anal fin is
provided; it then pushes itself upwards by straightening the tail, while
it closes the gill-covers not to prevent progress, and so on. Sir E.
Tennent, however, without disputing the evidence that these fish do
climb trees, says,--
The probability is, as suggested by Buchanan, that the
ascent which was witnessed by Daldorff was accidental,
and ought not to be regarded as the habit of the
animal.[123]
A great number of species of fish perform migrations. In relation to
intelligence, the most interesting of these is the migration of salmon,
which annually leave the sea to spawn in rivers, though there is some
doubt whether the same individuals spawn every year. There is no doubt,
however, that the same individuals frequently, though not invariably,
revisit the same rivers for their successive spawnings. This fact may be
due either to the remembrance of locality, similar to that which is
unquestionably manifested by birds, or to the salmon not swimming far
along the coast during other seasons of the year, and therefore in the
spawning season when seeking a river happening to hit upon the same one.
The latter hypothesis is one which Mr. Herbert Spencer tells me he is
inclined to adopt, and, being a salmon-fisher, he has paid attention to
the subject. He informs me of an observation by a friend of his own, who
saw a salmon, when about to spawn, swimming along the coast-line, and
all round a boathouse, apparently seeking any stream that it might first
encounter.
The distances up rivers to which salmon will swim in the spawning season
is no less surprising than the energy with which they perform the feat,
and the determination with which they overcome all obstacles. They reach
Bohemia by the Elbe, Switzerland by the Rhine, and, which is much more
wonderful, the Cordilleras of America by the Maragnon.
They employ only three months in ascending to the
sources of the Maragnon (a journey of 3,000 miles),
the current of which is remarkably rapid, which is at
the rate of nearly forty miles a day; in a smooth
stream or lake their progress would increase in a
fourfold ratio. Their tail is a very powerful organ,
and its muscles have wonderful energy; by placing it
in their mouths they make of it a very elastic spring,
for letting it go with violence they raise themselves
in the air to the height of from twelve to fifteen
feet, and so clear the cataract that impedes their
course: if they fail in their first attempt, they
continue their efforts till they have accomplished
it.[124]
_General Intelligence._
With reference to the general intelligence of fish, allusion may first
be made to their marked increase of wariness in waters which are much
fished. This shows no small degree of intelligence, for the caution is
proved to be the result of observation by the fact that young trout
under such circumstances are less wary than old ones. Moreover, many
fish will abandon old haunts when much disturbed. Again, according to
Kirby, the carp thrusts itself into the mud in order that the net may
pass over it, or, if the bottom be stony, makes great leaps to clear it.
At the Andaman Islands fish are captured by the
convicts by means of weirs fixed across the openings
of creeks. After existing a week or so, it is observed
that captures invariably cease; and it is believed
that such is due to barnacles, &c., clustering on to
the wood of which they are composed. It does not seem
improbable that the fish have learned to avoid a
locality out of terror at those which enter but do not
again return.[125]
Lacepède[126] relates that some fish, which had been kept for many years
in a basin of the Tuileries, would come when called by their names.
Probably it was the sound of the voice and not the articulate words to
which they responded; for Lacepède also relates that in many parts of
Germany trout, carp, and tench were summoned to their food by the sound
of a bell; and the same thing has been recorded of various fish in
various localities, notably by Sir Joseph Banks, who used to collect his
fish by sounding a bell.[127]
In 'Nature' (vol. xi., p. 48) Mr. Mitchell gives the following instance
of intelligence on the part of a small perch. Having one day disturbed
its nest full of young fry, Mr. Mitchell next day went to look for the
nest; 'but we searched in vain for the fish and her young. At length, a
few yards further up stream, we discovered the parent guarding her fry
with jealous care in a cavity scooped out of the coarse sand. . . . This is
the first and only instance that has come under my notice of a fish
watching over her young, and conveying them, when threatened with
danger, to some other place.'
In 'Nature' (December 19, 1878) there is also published a communication
which was made by Mr. J. Faraday to the Manchester Anglers' Association,
concerning a skate which he observed in the aquarium of that town:--
A morsel of food thrown into the tank fell directly in
an angle formed by the glass front and the bottom. The
skate, a large example, made several vain attempts to
seize the food, owing to its mouth being on the
underside of its head and the food being close to the
glass. He lay quite still for a while as though
thinking, then suddenly raised himself into a slanting
posture, the head inclined upwards, and the under
surface of the body towards the food, when he waved
his broad expanse of fins, thus creating an upward
current or wave in the water, which lifted the food
from its position and carried it straight to his
mouth.
It will be observed, however, that this observation is practically
worthless, from the observer having neglected to repeat the conditions
in order to show that the movements of the fish were not, in their
adaptation to these circumstances, purely accidental. Therefore I should
not have alluded to this observation, had I not found that it has been
quoted by several writers as a remarkable display of intelligence on the
part of the fish.
I must not take leave of this class without making some allusion to the
alleged habits of the so-called 'pilot-fish,' and also to those of
'thresher' and 'sword-fish.' I class these widely different habits
together because they are alike in being dubious; different observers
give different accounts, and therefore, until more information is
forthcoming, we must suspend our judgment with regard to the habits in
question. The following describes what these habits are believed by many
observers to be.
Captain Richards, R.N., says that he saw a blue shark following a bait
which was thrown out to him from the ship. The shark, which was attended
by four pilot-fish, repeatedly approached the bait; but every time he
did so one of the latter rushed in and prevented him. After a time the
shark swam away; but when he had gone a considerable distance, he turned
back again, swam quickly after the vessel, and before the pilot-fish
could overtake him, seized the bait and was caught. While hoisting him
on board, one of the pilots was seen to cling to his side until above
water, when it dropped off. All the pilots then swam about for a time,
as if searching for their friend, 'with every apparent mark of anxiety
and distress.'[128] Colonel Smith fully corroborates this observation; but
Mr. Geoffrey, on the other hand, saw a pilot-fish take great pains to
bring a shark to the bait.[129] Probably the truth is that the pilot-fish
attend the shark in order to obtain the crumbs that fall from his
feasts, and that the cases in which they appear to prevent his taking
the bait are without any psychological significance.
With regard to the alleged co-operation of the threshing and sword-fish
in the destruction of whales, all that can be said is that the
statements, although antecedently improbable, are sufficient in number
not to be ignored. Mr. Day appears to accept the evidence as adequate,
and gives the following cases:--
Captain Arn, in a voyage to Memel in the Baltic, gives
the following interesting narrative:--One morning
during a calm, when near the Hebrides, all hands were
called up at 2 A.M. to witness a battle between
several of the fish called threshers or fox-sharks
(_Alopecias vulpes_), and some sword-fish on one side,
and an enormous whale on the other. It was in the
middle of the summer; and the weather being clear, and
the fish close to the vessel, we had a fine
opportunity of witnessing the contest. As soon as the
whale's back appeared above the water, the threshers
springing several yards into the air descended with
great violence upon the object of their rancour, and
inflicted upon him the most severe slaps with their
long tails, the sounds of which resembled the reports
of muskets fired at a distance. The sword-fish in
their turn attacked the distressed whale, stabbing
from below: and thus beset on all sides and wounded,
when the poor creature appeared, the water around him
was dyed with blood. In this manner they continued
tormenting and wounding him for many hours, until we
lost sight of him; and I have no doubt they in the end
completed his destruction.
The master of a fishing-boat has recently observed
that the thresher-shark serves out the whales, the sea
sometimes being all blood. One whale, attacked by
these fish, once took refuge under his vessel, where
it lay an hour and a half without moving a fin. He
also remarked having seen the threshers jump out of
the water as high as the mast-head and down upon the
whale, while the sword fish was wounding him from
beneath, the two sorts of fish evidently acting in
concert.
FOOTNOTES:
[110] _Phil. Frags._, translated by Huxley, _Taylor's Mag._, 1853, p.
196.
[111] Silliman's _American Journal_, Feb. 1872.
[112] Ransom, _Ann. and Mag. Nat. Hist._, 1865, xvi., p. 449.
[113] Quoted from Francis Day, F.L.S., 'Instincts and Emotions of Fish,'
_Journ. Linn. Soc._, vol. xv., pp. 36-7, where see for other cases of
nest-building among fish.
[114] _Ibid._
[115] Kaup, _Catal. Lopho. Fish in Brit. Mus._ 1856, p. i.
[116] Yarrell, _Brit. Fishes_, 2nd ed. ii. p. 436.
[117] _Compt. Rend._, Nov. 4, 1872, p. 1127.
[118] _Phil. Trans. Royal Society_, 1747.
[119] F. Day, _loc. cit._
[120] Shelley, _Lines written in the Bay of Lerici_.
[121] See Smiles, _Lives of Engineers_, vol. iii., p. 69.
[122] See 'On the Jaculator-Fish,' by Schlosser, _Phil. Trans._ 1764.
[123] _Natural History of Ceylon_, p. 351.
[124] Kirby, _Hist. Habits and Instincts of Animals_, vol i. p. 119.
[125] F. Day, _loc. cit._
[126] _Hist. des Poiss._, _Introd._, cxxx.
[127] For sundry other similar cases see Mr. Day's excellent paper
already quoted.
[128] Cuv., _Anim. Kingd._ x. p. 636.
[129] F. Day, _loc. cit._