Animal Intelligence Part 22

Following this principle, we are also ent.i.tled 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 const.i.tutes 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. Hanc.o.c.k, 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 const.i.tutes 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 cla.s.s 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 a.n.a.l 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 sp.a.w.n in rivers, though there is some doubt whether the same individuals sp.a.w.n every year. There is no doubt, however, that the same individuals frequently, though not invariably, revisit the same rivers for their successive sp.a.w.nings. 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 sp.a.w.ning 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 sp.a.w.n, 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 sp.a.w.ning 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 circ.u.mstances 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 pa.s.s 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., cl.u.s.tering 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]

Lacepede[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 Lacepede 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. Mitch.e.l.l gives the following instance of intelligence on the part of a small perch. Having one day disturbed its nest full of young fry, Mr. Mitch.e.l.l 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 coa.r.s.e 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' a.s.sociation, 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 gla.s.s 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 gla.s.s. 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 circ.u.mstances, 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 cla.s.s without making some allusion to the alleged habits of the so-called 'pilot-fish,' and also to those of 'thresher' and 'sword-fish.' I cla.s.s 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] Sh.e.l.ley, _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._, cx.x.x.

[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._