1911 Encyclopædia Britannica/Mullet
MULLET, the name of two different kinds of fishes, distinguished as red mullets and grey mullets.
Red mullets (genus Mullus, the name given by the ancient Romans) are marine fishes, with two short dorsal fins remote from each other: the first is composed of feeble spines, the second of branched rays; the anal fin is similar to the second dorsal. The body is covered with large thin scales. The form of the head is peculiar; its anterior profile slopes downwards to the small mouth, which has very small and feeble teeth, and from which two cylindrical barbels are suspended. These organs of touch are generally laid backwards and hidden in a groove between the branches of the lower jaw, but can be erected and called into action independently. About forty different species of red mullets are known, chiefly from the tropical and subtropical parts of the Indo-Pacific ocean. In European waters two forms are known which have received different specific names, Mullus surmuletus and Mullus barbatus. The former in addition to the general red colour has three to five bright yellow bands along the sides from head to tail; these are absent in the other form. It has been proved that this is not a sexual difference, the two forms are varieties or species. The striped form is usually found on the coasts of England, where the plain form is rare or absent. In the Mediterranean both kinds occur, but it is probable that the striped form, which is larger, is more common in the Atlantic and the plain form in Mediterranean and southern waters.
Red mullets do not attain any considerable size, the largest of the tropical species weighing only two or three pounds. They are ground-feeders, evidently using their barbels in discovering their food, which consists of crustacea, worms, and, in the larger species, of small fishes; that they feed on putrid flesh is not borne out by the evidence drawn from their feeble jaws and dentition, but it is probable that they are attracted to a decomposing body by the presence of the small crustaceans which feast upon it. Although the colours of these fishes are brilliant, they are simple and evanescent; only a few of the tropical species exhibit ornamentations in the form of black spots or bands. In many, as also in the European species, red colour prevails, and its preservation after death is considered to enhance the fitness of the fish for the table, and consequently its market value. To produce the intensity of this red colour, fishermen scale the red mullet immediately before its death, a process by which the red pigment cells or chromatophores are excited to expand; fishes which are allowed to die in the water show little red, and therefore red mullets caught by the trawl are less valuable than those obtained in a trammel-net, by which the majority are secured alive. All the species are esteemed as food; but none equals the European species, which was held in exaggerated esteem by the gourmands of Rome. They exhibited the living fish and allowed them to die at the table immediately before they were consigned to the cook; they kept them in large reservoirs until they were wanted, and paid fabulous prices for fishes somewhat above the average size. Little is known about the habits of red mullets; during winter they retire into deep water, late in spring and during summer they approach the coasts and enter even brackish water, but the state of their sexual organs shows that they do not come towards the shore to breed. At Naples they spawn from May to August, and their ova are buoyant and transparent. In June, July and August the young are about an inch long, and already furnished with the two barbels.
The grey mullets form a widely different and distinct family, Mugilidae. They are not exclusively marine, but enter brackish water, live always close to the shore, and some of the tropical forms inhabit the pure fresh water of streams and rivulets, without, however, penetrating far inland. Their body is elegantly formed, wedge-shaped, and covered with scales of moderate size, firmly adherent to the skin. The two short dorsal fins are remote from each other, and the anterior is composed of four stiff spines. The anal fin is similar to the second dorsal; the caudal fin strong and bilobed. The form of the snout is peculiar; the mouth narrow, transverse in the true Mugil, and without, or with but feeble, teeth. About seventy different species are known, from almost every coast of the temperate and tropical zones; they swim in small schools and are abundant wherever they occur. Two species are found on the British coasts — Mugil capito and Mugil chelo, the first being the more common. Some of the fresh-water grey mullets of the tropics, especially those of the West Indian and Indo-Pacific islands, have the mouth more lateral or have distinct though minute teeth; they therefore have been formed into separate genera, Agonostoma and Myxus.
Grey mullets, at least some of the species, grow to a weight of 10 or 12 lb; but the fish which usually come into the market rarely exceed half that weight. Those in which distinct teeth are developed feed principally on small aquatic animals, whilst the diet of those without teeth consists of animalcules or minute organic substances mixed with the mud or sand which they swallow in large quantities; also confervoid growths to which small shells adhere are freely taken. To prevent the gills from being clogged by sand or mud, a peculiar apparatus separates these organs from the pharynx. Each branchial arch is provided on each side, in its whole length, with a series of closely-set gill-rakers, each series fitting into the series of the adjoining arch; they constitute together a sieve permitting the passage of the water, while retaining other substances in the cavity destined for mastication. The structure of the intestinal tract is also adapted to the diet of these fishes. One portion of the stomach is globular and surrounded by a thick mass of muscles, the cavity being small and coated with a tough epithelium. This structure reminds us of the stomach of birds, in which it also serves for the trituration of hard substances. The intestine itself is six or seven times as long as the fish. Grey mullets are plainly coloured, generally greenish on the upper parts and more or less silvery on the side. They are wholesome food, well flavoured when taken out of clean water. In the fish-farms of western Italy grey mullets are among the principal fish cultivated. (J. T. C.)