So we cannot do better than follow our own common Mackerel, as they migrate in shoals out of the deep sea to feed on the fry of the herring or the pilchard in shallower water, or to leave their eggs floating not many miles from land, so that the tiny mackerel, when hatched, may live in the quiet bays till their strength comes.

Footnote 36. Dactylopterus.

Footnote 37. Hippocampus.

Footnote 38. Xiphias.

But stop! Long before we have come so far as this, and while we are still a hundred miles or more from the shore, let us peep down into the sea-valleys, where forests of seaweed and marine plants are growing, and myriads of tiny sea-lice and crustaceans throng the water. What is that army of thin spindle-shaped forms rising and falling in such numbers? It is a shoal of herring, which have come there to feed upon the sea-animals, keeping out of sight of the sea-birds above, and the cod and sharks and ravenous fish which hunt them without mercy, so that they only venture to come to the surface on calm dark nights. It was in valleys such as these that the herrings were living when the older naturalists thought they were gone away to the Polar Seas, because they only saw them in spring and autumn, when they come into shallower water to drop their myriads of eggs,[39] which sink down, and stick to the seaweed and stones below.

But now they are revelling in the deep ocean, rising and falling with ease, for their air-bladder has two openings, one to the stomach and one to the outside of the body, so that the gas can adjust itself to their movements; and surely if the shark is the type of the old, lumbering, powerful, slow-breeding fish, the herring, with its narrow lissome body, light playful movements, and myriads of young, is the type of the new and active race. They are as truly social animals as any herds on land, for they travel in shoals of many hundreds of millions; and as they can squeak, and have a very good apparatus for hearing, it is more than likely that they call to each other. They

Footnote 39. At least 10,000 for each mother.

make both the salt and fresh water their own; for when the eggs are hatched at the mouths of rivers the tiny fish take refuge there from the violent persecutions of the cod and mullet and haddock, flat-fish and whiting, and, together with the small fry of other fish, stroll up the rivers, where we call them “white-bait.”

And now, as we come nearer to the shore, where countless numbers of small fry are filling the water, and all creatures are struggling together to accomplish three objects, namely, to get food, to avoid being turned into food, and to lay their eggs, we find many strange weapons and devices adopted by the different fish for protection and attack.

... “Each bay

With fry innumerable swarms, and shoals

Of fish, that with their fins and shining scales

Glide under the green waves, in sculls that oft

Bank the mid sea.”

There are the Mullets,[40] with tender feelers under their chin, with which they brush the ground lightly as they swim, feeding on the tiny creatures. There are the walking fish, the Gurnards,[41] which have three of the spines of their arm-fins separate, and moved by strong muscles and nerves, so that they can walk on the sea-bottom, feeling their way, while the stiff, spiny rays of their back-fin stand up to wound any enemy attacking them from above. There are the tiny Blennies which walk too, but by means of the few rays which alone remain of their leg-fins growing close under the head. Then there are the clinging-fish, the Gobies,[42] living on the rocky shores, where

Footnote 40. Mullus.

Footnote 41. Trigla.

Footnote 42. Gobidæ.

the waves beat and roar, and they have their leg-fins joined together, so as to form a kind of funnel under their throat, with which they cling to the rocks and then dart across the waves to feed, coming to anchor again out of the dash of the water; some of these little fellows make nests and guard their eggs after the mother has left them, till the young can shift for themselves. More curious still, the Lumpsucker[43] has its arm-fins and leg-fins all joined together into a round disk under the throat, and so holds on bravely against the dashing tide, defending the eggs which have been laid in the seaweed near the shore, and even remaining to take up the young ones when hatched, and carry them safely back into deep water as they cling to his sides.

Meanwhile, close down upon the sand are the hiding-fish, the Weevers, the Anglers, and the Flat-fish.

The weevers[44] are the most dangerous. Their shaded yellow colour hides them from view, while the sharp spines of their back-fins, which they keep raised, will inflict very severe, if not poisonous, wounds on any creature striking against them. Nor is this all, for behind the cheeks, fastened on to the horny gill cover, are daggers with which they can strike, deliberately jerking them back so as to give a sharp blow. These are fighting aggressive fish, waging the war that goes on so sharply all round our coasts.

Fig. 11.

The Fishing Frog.[45]

But there is one even more cunning than they, lying hidden in the seaweed or the sand—a large, flat, soft fish, about three feet in length, and quite half as broad as he is long, with a soft stumpy

Footnote 43. Cyclopterus.

Footnote 44. Trachinidæ.

Footnote 45. Lophius piscatorius.

tail, stretching out behind, and a kind of wrist-joint to arm and leg fins, by which he can creep noiselessly along. His wide mouth is gaping open, so that a two-foot rule could be passed crossways into it, and his pointed teeth are bent back to allow his prey to enter. But how is this prey to be caught, for he is not going to move to fetch it? Notice all round his head and his body, the skin is fringed like blades of seaweed and plays about in the water; while above his head and back the spines of his fin stand up quite separate, and the front one

is tapering and long like a fishing-rod, with a lappet at the end like a bait. And now, as the shallow water ripples over his head, the lappet plays to and fro, and the unwary fish come up to nibble at it, lower and lower he waves it, and the nibblers follow, till, opening his wide gape, he gulps them down, even if they are as large as himself, and lies passive with his swollen stomach till they are digested. This is our own Fishing-frog,[46] of which one was once found with seventy herrings in his stomach. He has relations all over the world—in the open sea and down in its depths, and all of them more or less follow his fishing habits. Yet there is no creation of special parts for these strange weapons; the altered back-fin and the jagged skin do all the work, just as in some curious fish of the weever family in the tropics, called the Stargazers,[47] the feelers on their lips, longer than those of other fishes, and a lengthened thread from below the tongue, play in the watery currents and attract the small animals, while the fish with upturned eyes watches them as they are lured to destruction.

Lastly, among all these curious forms upon our shores there is an abundance of flat-fish—soles and turbot, brill and plaice—flapping along at the bottom, covering themselves with sand, or rising up with that strange wavy movement of the whole body in which they use what look like long side-fins, but which are really the back-fin and the belly-fin.

Fig. 12.

The Common Sole.[48]

Above are two small soles as they swim when young. At that time they are not larger than a grain of rice.—(Adapted from Figuier and Malm.)

If we wanted to pick out the strangest and strongest proof of how the shape of fish is altered to suit their wants, we need seek no further than the flat-fish.

Footnote 46. Lophius.

Footnote 47. Uranoscopus.

Footnote 48. Solea vulgaris.

When we were speaking of the shark order we saw that the rays and skates are flattened forms suited to hide in the sand, and these fish are truly spread out as if they had been squeezed under a heavy weight, their broad arm-fins edging the sides of their body. But the bony flat-fish, the Soles and Turbot, have a far stranger history. The young sole, when it comes out of the egg, is not flat like the young skate, but a very thin spindle-shaped fish, something like a minnow. He is then about the size of a grain of rice, very transparent, and lives at the top of the sea.

He has one eye on each side, like other fish, only one eye is higher up than the other, and the single fin on its back and the one under its body reach almost from head to tail. In this way he swims for about a week, but he is so thin and deep, and his fins are so small, that swimming edgeways is an effort, and soon he falls down on one side, generally the left, to the bottom of the sea. Many times he rises up again, especially at first, till he has got used to breathing at the muddy bottom, and meanwhile the eye that lies underneath is gradually working its way round to the upper side, his forehead wrinkles so as to draw the under eye up, while his whole head and mouth receive a twist which he never afterwards loses. His skeleton, it must be remembered, is still very soft, and the bones of his face are easily bent; and at last this eye is screwed round, and as he lies at the bottom he can look upwards with both eyes and save the under one from getting scratched by the sand, as it must have done if it had remained below.

Nor is this all, for while his under side, shaded from the sunlight, remains white and colourless, his upper side gradually becomes coloured like the sand in which he lies, and he is safely hidden from attack as he flaps along, feeding on worms and other animals. And now when he swims he no longer uses his arm and leg fins, which are quite small and insignificant, but bends his whole body, using the back and belly fins to help him. What we then call the top of the sole is really his side, where you may see the dark line of scales running along the middle, and one arm-fin lying close to his head. Yet he can swim strongly and to far distances, for in the winter the soles, too, migrate into the open sea, where they may be found in the deep water of the Silver Pit, between the Dogger Bank and the Well Bank.

Fig. 13.

Hippocampus, a fish commonly called the Sea-Horse.

And now, before we leave the shore, we must glance at a curious weakly little fellow clinging by his curly tail to the seaweed, whom you will certainly not take for a fish, even if you can find him out, so entangled is he generally in weeds of the same colour as himself. Yet the Sea-horse[49] is a true fish, covered not with scales but with plates, with which he makes a clicking noise by scraping them together. What look like large ears are really his arm-fins, while at the end of his long snout is a mouth shaped like an ordinary fish’s mouth, but toothless, and he breathes with fish’s gills arranged in round tufts instead of folds. What the use of his strange shape is to him we cannot tell, but at any rate his fleshless bony body must protect him from other fish, while his power of clinging causes him

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