Sea-bats and Dories 623

" " young of the horse-mackerel seeking shelter beneath the umbrella of a jelly-fish till they are big enough to defend themselves.

But the most remarkable members of this family are the SEA-BATS. Few in species and confined to the Eed Sea, Indian Ocean, and Western Pacific, they are nevertheless in those regions very common. Although not used as food-fishes, they are of extreme interest on account of their shape, which is nearly oval and much compressed from side to side, and the form of their fins, which in some species are excessively developed. Young sea-bats differ markedly from the adults in the much greater length of the fin-rays, so much so that they have frequently been described as distinct species. \Ve pass now to the DORIES, which recall the Sea-bats in the oval and compressed form of the body. The resemblance to sea-bats is, indeed, so close that the latter are frequently described as dories. The mouth of the members of this family is so constructed that, is thrust forward, and the whole mouth forms a kind of long tube.when opened, the upper jaw Dories inhabit the seas of the temperate regions, two species being fairly common in British waters. The best known of these two is perhaps the JOHN DORY, the largest specimens of which attain to a weight of 18 Ibs. Mr. Cunningham has described the very peculiar way in which the dory captures its prey. "It does not," he writes, " overtake it by superior speed like the mackerel, or lie in wait for it like the angler, but stalks it and approaches it by stealth. It is able to do this in consequence of the extreme thinness of its body and the peculiar movement of its hinder dorsal and ventral fins. The dory places itself end on towards the fish it desires to devour, and in this position it is evident that it excites no alarm on the part of its prey. The appearance of the dory, seen in this way, is a mere line in the water, to which no particular significance can be attached. I have not particularly noticed the effect of the ribbons of membrane which project from the dorsal fin. But I have observed that the movements of the dory are very gradual, except in turning; it alters the position of its body by a Photo by W. Saville-Kent, F.Z.S.} [MU/ord-on-Sea. turn of the tail or side-fins, LONG-FINNED DORY. and then swims forward by This species closely resembles a fossil form. It has nothing to do with the True Dories, but is vibrating the second dorsal one of the Coral-fishes, and is placed here for the sake of contrast.

and ventral, a movement which causes very slight disturbance of the water. The appearanct, of the dory in these actions is suggestive of suppressed excitement, his eyes being fixed on his prey. I do not recollect seeing him actually swallow another fish, but have no doubt that he gets near enough to a sprat, for example, without alarming it, to seize it by the sudden elongation of his curious jaws." The way in which these jaws are elongated is admirably shown in the photograph on page 622.

Passing now to the Mackerel Family, we arrive at a group of considerable importance from an economic point of view. Extremely active, migrating, and predaceous, mackerel swim in shoals and seize their prey with great voracity, hunting merely by sight, and snapping at anything moving through the water, especially if it is silvery, like a small surface-fish. The various species differ greatly in size, ranging from the Common Mackerel of about 18 inches long to the giant Tunny weighing nearly half a ton.

COMMON MACKEREL swim in vast shoals, or " schools," as they are called, and one half a mile wide and at least twenty miles long is on record. Mackerel feed on the young of other fish and small fish generally, and, when these are not to be had, on minute crabs and shrimps. They are very prolific, a single mackerel laying from 430,000 to 540,000 eggs. The TUNNIES are amongst the largest of the surface-fishes of the ocean. Abundant in the Mediterranean Sea, they occur occasionally in British waters. For centuries the flesh of the tunny has been held in high regard as food, and it is frequently seen in the Lisbon markets at the present day. The flesh, which is as red as Photo by Reinlwld Thide & Co.] [Chancery Lane, W.C. beef, is cut up and sold JOHN DORY. by weight. The BONITO In the centre of each side is a round black spot surrounded by a pale yellow ring. closely resembles the tunny, but is a much smaller fish, which preys largely upon flying-fishes, which it follows for long distances.

Peculiarly interesting are the SUCKING-FISHES. The name by which they are commonly known is bestowed on account of the presence of a large oval sucker, placed on the top of the head and extending backwards over the shoulders an organ formed by modification of the back-fin. By means of this sucking-disk these fishes are enabled to attach themselves to sharks, turtles, ships, or any large object floating in the sea. The hold which they obtain force. Being poor swimmers,is so strong that it is almost impossible to remove them by this method of transportation enables them to pass rapidly to fresh feeding-grounds. in The natives of Zanzibar, Cuba, and Torres Straits are said to employ sucking-fishes the capture of sleeping turtles, the fish being secured by a ring round the tail, and liberated as soon as a sufficiently near approach to the quarry has been made. About ten different species are known, the bulkiest of which attains a length of 2 feet and a weight of about 8 Ibs., a longer but more slender species measuring 3 feet,

Carnivorous, of small size, and feeble swimming-powers, the family of the "WEAVERS are remarkable rather for their disagreeable qualities than anything else, though at least one

Weavers and Frog^fishes 625

Photo by W Saville-Keiit, F.Z.S.] [ Milford-on-Sea. SUCKING-FISH. By means of the sucker on the top of its bead this fish attaches itself to ships and larger fishes.

species is declared to be excellent eating. The STAR-GAZER is a particularly ugly-looking fish, especially noteworthy in that the eyes, which are on the top of the head, can be raised and depressed at pleasure, whilst the heavy jaw is armed with a freely moving tentacle, which, waving about in the current of water drawn in at the mouth, serves as a lure to attract small fishes, the rest of the body being concealed between stones at the bottom of the sea.

The COMMON WEAVER is a well-known British fish,- much dreaded on account of the poisonous wounds which it inflicts unless most carefully handled, the poison being introduced by the spines of the back-fin and gill-cover. No special poison-organs seem to be developed, but the mucous secretion around the spines has poisonous properties. As the flesh of this fish is extremely palatable, fishermen remove the spines at once directly after capture. Should a wound be inflicted, great suffering and occasionally death follows.

Passing over one or two unimportant groups, we come to the family of the FROG-FISHES, which, but for the fact that many of its members are poisonous, calls for no special comment here. One species, however, from the coasts of Central America, possesses the distinction of having the most highly developed poison-organs of any fishes, being equalled only by the

Photo ly Meinhold Thiele & Co.] [Chancery Lane, W.C.

LARGER WEAVER.

The spines of the first back-fin and of the gill-cover are highly poisonous. 79

of the World 626 The Living Animals

Venomous Snakes. The poison-weapons are a spine on the gill-cover and two spines of the back-fin. The former is of the same shape as the hollow venom-fang of a snake, perforated lies at the base of the spine, and when at both ends. A little bag containing the poison pressed by the spine as it makes its puncture ejects its contents into the body of the latter, whence it escapes from the hole in the top. The structure of the back-spines is similar.

The family of the ANGLER-FISHES contain more strange forms than any other. Living on the sea-bottom and seeking their prey by stealth, angler-fishes do not need powerful swimming-muscles; consequently the size of the body and tail has become considerably reduced, so that the head, relatively to the rest of the body, is unusually large. The head, jaws, and belly are indeed of great size and capacity. The side or paired fins are not used for swimming, but have become modified to serve as feet, enabling the fish to shuffle fishes is seen in the back-fin, along the ground. A further remarkable feature of these the rays of which are very long, the foremost being provided with a flag-like flap of skin at

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Photo liy Reinhold Thule d: Co.} [Chancery Lane, W.C. ANGLER-FISH. This hideous species is also called the Frog-fish. the top, extremely sensitive to touch, and playing a very important part in the capture of " " food. It seems that the fish commonly lies concealed on the sea-bottom, with this flag it is quite inconspicuous,erected. From its general resemblance to the surrounding seaweed it. If by any chanee they should touch it,so that passing fishes take no trouble to avoid however, the jaws beneath open instantly, and the unfortunate trespasser is suddenly engulfed. This elaborate and sensitive mechanism has been likened to a spring-trap, which is always set, and never betrays its presence. It seems probable, however, that this flag serves also as a lure, passing fishes being occasionally attracted by the waving flap of skin. Should they become sufficiently curious as to proceed to touch it, capture in the manner above described is certain. Certain deep-sea forms have a luminous organ in the place of the flap of skin, and this certainly seems to act only as a lure.

Angler-fishes are found all over the world; some, as we have seen, are bottom-fishes, some inhabit deep sea, whilst others lie hidden amongst floating seaweed, to which they cling by

means of their

arm-like fins. Only

one species occurs

in British waters.

Its method of

spawning is remarkable, in that the

eggs are laid in the

form of large raftlike sheets, which

float. on the surface

of the sea. The

number of eggs laid

by a single fish has

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