Photo by Dr. Robert T. Morris, New York

A SALMON LEAPING.

The height to which salmon will leap in ascending a waterfall is little short of marvellous. When the fall is very high the ascent is often accomplished in a series of leaps, the fish resting in pools of comparatively still water.

UNIV. OF

CALIFORNIA

CHAPTER Viil.

THE COD FAMILY.

BY JOHN BICKERDYKE, M.A.

in which both sides of the head are symmetrical. The Common Cod, the Whiting,THEgrouplarge and important Cod Family belongs to the order of Spineless Fishes and the the Haddock, the Pollack, the Coal-fish, the Hake, the Ling, and the little Kocklings, all belong to this important family, which has one representative in fresh-water, the Burbot, or Eel-pout, found in various rivers in Central and Northern Europe and North America. is the CHIASMODUS, which has Perhaps the most remarkable member of the Cod Family fcmge jaws lined with large pointed teeth, and a distensible stomach and abdomen. During the Challenger Expedition a specimen was taken 1,500 fathoms down in the North Atlantic. It had swallowed another fish, a kind of scopelus, more than twice its own size. The stomach of the chiasmodus had swelled to an enormous extent, and had become so thin from distension that the fish inside could be clearly seen through its walls. The scopelus, it is interesting to mention, is a fish brought up sometimes by the dredge from 2,500 fathoms. It occasionally comes to the surface at night, and has phosphorescent spots along its sides, giving out a dim light, which has its uses in the dark depths of the sea.

To come back to the head of the family, the COD is a fairly plentiful fish all around the British and Irish coasts, but appears to be decreasing in some waters as time goes on, owing to the over-trawling of the North Sea. Off the coasts of Norway, in the neighbourhood of the Lofoden Islands, the cod are sometimes so thickly packed in shoals that as the fishermen-

Photo by A. S. Rudland & Sons. WHITING. Easily distinguished from the cod by the absence of a barbel on the chin. 641 81

lower their tackle they can feel the leads hitting the backs of the fishes. Both there and off the Faroe Islands and Iceland it is common practice to fish with a hook bearing a little piece of polished lead on its shank, no other bait being required, owing to the cod being so numerous that food is scarce. About the commencement of the fifteenth century the English began to go to Iceland for cod, and since the sixteenth century English cod-fishing vessels have visited Newfoundland and other far northern waters, which produce fish superior to English cod. It should be mentioned that the Cod Family is not found to any extent in tropical seas.

While the BURBOT is one of the few species of the group inhabiting fresh-water, and is peculiar in living there permanently, there are instances recorded of POLLACK having ascended it is an undoubtedfrom the salt water of the Norwegian fiords into fresh-water lakes, and (act that many other species of sea-fish can accustom themselves to a residence in fresh-water.

All through the year cod frequent the British coasts; but it is two or three months before

Photo ly W. SavilU-Kent, F.Z.S.} [Milford-on-Sea. POLLACK-WHITING. A British representative of the group in which the lower jaw is the longer and all the teeth of the upper jaw are of equal size.

locality, that theythe spawning-season, which commences in January or later according to the gather in vast shoals and come close inshore. First come the small codling of a pound or so, and as the winter approaches the longshore fish are found gradually to increase in size, until by Christmas-time it is no uncommon thing on the east coast of England and Scotland for fish of from 10 to 20 Ibs. to be caught from the beach.

As a rule the eggs of cod float, owing to a little globule of oil which each one contains, but in water which lacks salinity they sink. The quantities of eggs shed by each fish are enormous; nearly two millions were counted in a cod of a little under 12 Ibs. It is fairly certain, however, that not more than two or three, if so many, mature fish are the product of the two million eggs; for if each fish even doubled itself in numbers (if we may use the expression) every year, the sea would soon contain more fish than water. Millions upon is an on-shore wind during the spawning-season.millions of eggs are destroyed when there Sometimes the shore on which they have been wafted has been seen to glisten with them.

By the end of summer such of the young cod-fish as have escaped their many dangers attain about 1 inch in length. They are very varied in colour, which depends on that of the

The Cod Family 643

seaweed and their other surroundings. The parent fish, too, vary somewhat in appearance, those round the English coast as a rule having brown backs with irregular spotty markings on the sides, while those from more northern waters usually have darker backs and are less often spotted. Cod are most enormous feeders, and in consequence grow very rapidly. At the Southport Aquarium codling of only f Ib. increased in weight to 6 or 7 Ibs. in about sixteen months. So voracious is the cod that it is very apt to swallow anything it sees moving, without considering whether it is wholesome. In 1879 a black guillemot in perfect condition was removed from the stomach of one of these fish; while among other strange finds by cod-fishermen from the same receptacle was a piece of tallow candle 7 inches long, a hare, a partridge, a white turnip, and, going back to the year 1626^ a "work in three treatises," which was found in the stomach of a fish captured in Lynn Deeps on midsummer eve, and brought to the Vice-Chancellor of Cambridge. The usual food of cod is, however, small fish of various kinds herrings, pilchards, sprats, crabs, and sea-worms; but the species is not particular what it seizes is scarce owing to the number of mouths.when shoaling before the spawning-season and food

CHAPTER IX.

CAVE-FISHES, SAND-EELS AND THEIR ALLIES, AND FLAT-FISHES.

BY W. P. PYCRAFT, A.L.S., F.Z.S.

subterranean fresh-water caves of Cuba furnish the most interesting and most remarkable members of the family in certain small fishes known as CAVE-FISHES. Living in completeTHE darkness, the eyes have degenerated so as to be no longer useful as organs of sight; indeed, in many species they are entirely wanting. By way of compensation delicate organs of touch have been developed, taking the form, in different species, of barbels, hair-like processes, or tubercles. These blind fishes are closely allied to certain marine forms found in the tropical Atlantic and Indian Oceans, and it is curious to note that amongst these about seven very rare species are found at great depths in the southern oceans, so great that light fails to reach them, and they too are blind.

The SAND-EELS, or LAUNCES, are extremely common on the sandy shores of Europe and North America, living in vast shoals, and displaying a wonderful unison in their movements, rising and falling as with one accord. They burrow in the sand with amazing rapidity, forcing

Photo by W. SavilU-Kent [JUil/ord-on-Sea.

SPOTTED SOLE.

A larger and coarser fish than the common sole.

of the World644 The Living Animals

their way by means of a horny projection on the lower jaw, and remaining buried at ebb-tide some 5 or 6 inches under the sand, when they are captured by fishermen, armed with rakes, for in shoals, their presence is often betrayed by schools of porpoises, whichbait. When swimming feed greedily upon them, preventing their return to the bottom by getting under the shoal, whilst others swim round it. Mackerel also make large raids upon the ranks of such shoals.

FLAT-FISHES may be reckoned among the most important of food-fishes, and besides are of quite peculiar interest, on account of the remarkable modifications of structure which they have undergone. They differ from all other vertebrates in that, save for the first few weeks of existence, they spend the whole of their lives with one side of the body uppermost the right or left, according to the species. Whether resting or swimming, this position holds good. The newly hatched fish, however, maintains the normal poise of the body, the back being uppermost. Of the many changes which the organs of the body undergo during this " flat is thatstrange transformation from a " round " to a " fish, one of the most interesting which concerns the eyes. These, in the very young fish, lie one on either side of the head; but as the fish grows older it begins to lie on its side on the ground, and ultimately, when it is two or three months old, loses the power of sustaining itself in an upright position altogether. The most remarkable feature in this very strange mode of development is, that as the fish comes to lie more and more on its side, so the eye which is undermost begins to move round to the other side, till eventually the two eyes lie side by side on the upper-surface. Strangely enough, in some species the eye moves round the head, passing over its edge, and so to its place beside the stationary eye, whilst in others it acquires its ultimate position by moviirg through the -head, sinking in on one side and appearing again on the other. The coloration of - these fishes is also peculiar, in that the two sides are quite differently coloured, the upper side resembling in tone that of the sea-bottom, whilst the under side is pure white. In the young fish, before the habit of lying on one side has been acquired, both sides are coloured alike. The difference in coloration between the two sides of the adult fish appears to be due to the effect of light, since in flat-fishes kept in a tank with

'V*

Photo by W. Saville-Kmt, F.Z.S.] [ MilJ'ord-on-Sea. HALIBUT. The largest member of the Flat-fish Family. The back-fin usually commences much farther forward.

Flat-fishes 645

a mirror at the bottom the iinder-surface was found in many cases to be very largely coloured. But the colour of the upper-surface is by no means constant. On the contrary, the flat-fish appears to possess the power, in common with all other fishes, of changing its colour so as to harmonise with the tone of its surroundings. Thus on a light sandy ground the exposed surface of the body becomes pale, while on a dark muddy bottom it is almost black. By this power of changing the colour of the exposed portion of the body so as to Photo by W. Saville-Kent, F.Z.S.] [Milford-on-Sea. harmonise with the surround-oil the left side of the head, instead of on the right side, as in theings, the fish is enabled to As in the turbot, the eyes are become in a large measure halibut. invisible, and in proportion to the effectiveness of the change to escape its enemies. Some soles are quite invisible.

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