by Aristotle
The life of animals, then, may be divided into two parts, procreation and feeding; for on these two acts all their interests and life concentrate. Their food [5] varies chiefly according to the matter of which they are severally constituted; for the source of their growth in all cases will be this substance. And whatsoever is in conformity with nature is pleasant, and all animals pursue pleasure in keeping with their nature. [10]
2 · Animals are also differentiated locally: that is to say, some live upon dry land, while others live in the water. And this differentiation may be interpreted in two2 different ways. Thus, some animals are termed terrestrial as inhaling air, and others aquatic as taking in water; and there are others which do not actually take in these elements, but nevertheless are naturally adapted to the cooling influence, so [15] far as is needful to them, of one element or the other, and hence are called terrestrial or aquatic [though they neither breathe air nor take in water.]3 Again, other animals are so called from their finding their food and fixing their habitat on land or in water: for many animals, although they inhale air and breed on land, yet derive their food from the water, and live in water for the greater part of their lives; and [20] these are the only animals which seem to be ambivalent—for you might class them both as terrestrial and as aquatic. There is no animal taking in water that is terrestrial or that derives its food from the land, whereas of the great number of land animals inhaling air many get their food from the water; moreover some are [25] such that if they be shut off altogether from the water they cannot possibly live, as for instance, the so called seaturtle, the crocodile, the hippopotamus, the seal, and some of the smaller creatures, such as the fresh-water tortoise and the frog: now all these animals choke if they do not from time to time breathe; they breed and rear [30] their young on dry land, or near the land, but they pass their lives in water.
But the dolphin is equipped in the most remarkable way of all animals: the dolphin and other similar aquatic animals, including the other cetaceans which resemble it;4 that is to say, the whale, and all the other creatures that are furnished [589b1] with a blow-hole. One can hardly allow that such an animal is terrestrial and terrestrial only, or aquatic and aquatic only, if by terrestrial we mean an animal that inhales air, and if by aquatic we mean an animal that takes in water. For the fact is the dolphin performs both these processes: he takes in water and discharges it [5] by his blow-hole, and he also inhales air into his lungs; for the creature is furnished with this organ and respires thereby, and accordingly, when caught in the nets, he is quickly suffocated for lack of air. He can also live for a considerable while out of the water, moaning and groaning, like other animals that breathe; furthermore, when [10] sleeping, the animal keeps his nose above water, so that he may breathe the air. Now it would be unreasonable to assign one and the same class of animals to both categories seeing that these are contrary to one another; we must accordingly supplement our definition of the term ‘aquatic’. For the fact is, some aquatic animals take in water and discharge it again, for the same reason that leads [15] air-breathing animals to inhale air: in other words, with the object of cooling the blood. Others take in water as incidental to their mode of feeding; for as they get their food in the water they cannot but take in water along with their food, and if they take in water they must be provided with some organ for discharging it. Those sanguineous animals, then, that use water for a purpose analogous to respiration are provided with gills; and such as take in water when feeding, with the blow-hole. [20] Similar remarks are applicable to cephalopods and crustaceans; for again it is by way of procuring food that these creatures take in water.
Aquatic in different ways, the differences depending on bodily constitution and on habit of life, are such animals on the one hand as take in air but live in water, and such on the other hand as take in water and are furnished with gills but go upon [25] dry land and get their living there. At present only one animal of the latter kind is known, the so-called water-newt; this creature is furnished not with lungs but with gills, but for all that it is a quadruped and fitted for walking on dry land.
In the case of all these animals their nature appears in some kind of a way to have got warped, just as some male animals get to resemble the female, and some female animals the male. The fact is that animals, if they be subjected to a [30] modification in minute organs, are liable to immense modifications in their general configuration. This phenomenon may be observed in the case of gelded animals: [590a1] only a minute organ of the animal is mutilated, and the creature passes from the male to the female form. We may infer, then, that if in the primary conformation of the embryo an infinitesimally minute but essential organ sustain a change of magnitude, the animal will in one case turn to male and in the other to female; and also that, if the said organ be obliterated altogether, the animal will be of neither one sex nor the other. And so by the occurrence of modification in minute organs it [5] comes to pass that one animal is terrestrial and another aquatic, in both senses of these terms. And again, some animals are ambivalent, whilst other animals are not ambivalent, owing to the circumstance that in their conformation while in the [10] embryonic condition there got intermixed into them some portion of the matter of which their subsequent food is constituted; for, as was said above, what is in conformity with nature is to every animal agreeable.
Animals then have been categorized into terrestrial and aquatic in three ways, [15] according to their taking in of air or of water, the constitution of their bodies, or the character of their food; and the mode of life of an animal corresponds to the category in which it is found. That is to say, in some cases it depends on constitution and diet combined, as well as upon its method of respiration; and sometimes on constitution and habits alone.
Of testaceans, some, that are incapable of motion, subsist on fresh water (for, [20] being thinner than the seawater which concocts with it, it percolates through the grosser parts)—just as they were originally engendered from the same. Now that fresh water is contained in the sea and can be strained off from it is plain; for a test has already been made to prove it: take a thin vessel of moulded wax, attach a cord [25] to it, and let it down quite empty into the sea: in twenty-four hours it will be found to contain a quantity of water, and the water will be fresh.
Sea-anemones feed on such small fishes as come in their way. The mouth of this creature is in the middle of its body; and this fact may be clearly observed in the case of the larger varieties. Like the oyster it has a duct for the outlet of the [30] residuum; and this duct is at the top of the animal. In other words, the sea-anemone corresponds to the inner fleshy part of the oyster, and the stone to which the one creature clings corresponds to the shell.
The limpet detaches itself from the rock and goes about in quest of food. Of shell-fish that are mobile, some are carnivorous and live on little fishes, as for [590b1] instance, the purple murex—and there can be no doubt that the purple murex is carnivorous, as it is caught by a bait of fish; others feed also on marine vegetation.
The sea-turtles feed on shell-fish—for their mouths are extraordinarily hard; [5] (whatever object it seizes, stone or other, it crunches into bits, but when it leaves the water it browses on grass). These creatures suffer greatly, and oftentimes die when they lie on the surface of the water exposed to a scorching sun; for they find a difficulty in sinking again.
Crustaceans feed in like manner. They are omnivorous; that is to say, they live [10] on stones, slime, sea-weed, and excrement—as for instance the rock-crab—and are also carnivorous. The crayfish can get the better of fishes even of the larger species, though in some of them it occasionally finds more than its match. Thus, this animal is so overmastered by the octopus that it dies of terror if it become aware of an [15] octopus in the same net with itself. The crayfish can master the conger-eel, for owing to the rough spines the eel cannot slip away. The conger-eel, however, devours the octopus, for owing to the slipperiness of its antagonist the octopus can [20] make nothing of it. The cr
ayfish feeds on little fish, capturing them beside its hole; for it is found out at sea on rough and stony bottoms, and in such places it makes its den. Whatever it catches, it puts into its mouth with its pincer-like claws, like the [25] crab. Its nature is to walk straight forward when it has nothing to fear, with its feelers hanging sideways; if it be frightened, it makes its escape backwards, darting off to a great distance. These animals fight one another with their claws, just as rams fight with their horns, raising them and striking their opponents; they are [30] often also seen crowded together as it were in herds. So much for the mode of life of the crustacean.
Cephalopods are all carnivorous;5 and of cephalopods the calamary and the cuttlefish are more than a match for fishes even of the large species. The octopus for [591a1] the most part gathers shell-fish, extracts the flesh, and feeds on that; in fact, fishermen recognize their holes by the number of shells lying about. Some say that the octopus devours itself, but this statement is incorrect—in fact, some have had [5] their tentacles eaten off by the conger.
Fishes all feed on spawn in the spawning season; but in other respects the food [10] varies with the varying species. Some fishes are exclusively carnivorous, as the Selachia, the conger, the channa, dentex, the tunny, the bass, the bonito, the sea-perch, and the muraena. The red mullet is carnivorous, but feeds also on sea-weed, on shell-fish, and on mud. The grey mullet feeds on mud,6 the dascyllus [15] on mud and excrement, the scarus and the melanurus on sea-weed, the saupe on excrement and sea-weed; the saupe feeds also on zostera,7 and is the only fish that is captured with a gourd. All fishes devour their own species, with the exception of the mullet; and the conger is especially ravenous in this respect. The cephalus and the mullet in general are the only fish that eat no flesh; this may be inferred from the [20] facts that when caught they are never found with flesh in their intestines, and that the bait used to catch them is not flesh but barley-cake. Every fish of the mullet-kind lives on sea-weed and sand. The cephalus, called by some the chelon, keeps near in to the shore, the peraeas keeps out at a distance from it, and feeds on a [25] mucous substance exuding from itself, and consequently is always in a starved condition. The cephalus lives in mud, and is in consequence heavy and slimy; it never feeds on any other fish. As it lives in mud, it often makes a leap upwards so as to wash the slime from off its body. There is no creature known to prey upon the spawn of the cephalus, so that the species is exceedingly numerous; when, however, [591b1] the fish is fullgrown it is preyed upon by a number of fishes, and especially by the bass. Of all fishes the mullet is the most voracious and insatiable, and in consequence its belly is kept at full stretch; whenever it is not starving, it may be considered as out of condition. When it is frightened, it hides its head in mud, under [5] the notion that it is hiding its whole body. The synodon is carnivorous and feeds on cephalopods. Very often the synodon and the channa cast up their stomachs while chasing smaller fishes; for fishes have their stomachs close to the mouth, and are not furnished with a gullet.
Some fishes then, as has been stated, are carnivorous, and carnivorous only, as [10] the dolphin, the synodon, the gilthead, the selachians, and the cephalopods.8 Other fishes feed habitually on mud or sea-weed or sea-moss or the so-called stalk-weed or growing plants; as for instance, the phycis, the goby, and the rock-fish; and the only [15] meat that the phycis will touch is that of prawns. Very often, however, as has been stated, they devour one another, and especially do the larger ones devour the smaller. The proof of their being carnivorous is the fact that they can be caught with flesh for a bait. The bonito, the tunny, and the bass are for the most part carnivorous, but they do occasionally feed on sea-weed. The sargue feeds on the [20] leavings of the red mullet. The red mullet burrows in the mud, and when it sets the mud in motion and quits its haunt, the sargue settles down into the place and feeds on what is left behind, and prevents any smaller fish from settling in the immediate vicinity.
Of all fishes the so-called scarus is the only one known to chew the cud like a quadruped.
As a general rule the larger fishes catch the smaller ones in their mouths whilst [25] swimming straight after them in the ordinary position; but the selachians, the dolphin, and all the cetacea must first turn over on their backs, as their mouths are placed down below; this allows a fair chance of escape to the smaller fishes, and, indeed, if it were not so, there would be very few of the little fishes left, for the speed and voracity of the dolphin is something marvellous.
Of eels a few here and there feed on mud and on chance morsels of food thrown [592a1] to them; the greater part of them subsist on fresh water. Eel-breeders are particularly careful to have the water kept perfectly clear, by its perpetually flowing on to flat slabs of stone and then flowing off again; sometimes they coat the eel-tanks with plaster. The fact is that the eel will soon choke if the water is not [5] clear, as his gills are peculiarly small. On this account, when fishing for eels, they disturb the water. In the river Strymon eel-fishing takes place at the rising of the Pleiads, because at this period the water is troubled and the mud raised up by contrary winds; unless the water be in this condition, it is as well to leave the eels alone. When dead the eel, unlike the majority of fishes, neither floats on nor rises to [10] the surface; and this is owing to the smallness of the stomach. A few eels are supplied with fat, but the greater part are not. When removed from the water they can live for five or six days; for a longer period if north winds prevail, for a shorter if south winds. If they are removed in summer from the pools to the tanks they will [15] die; but not so if removed in the winter. They are not capable of holding out against any abrupt change; for example, they often die in large numbers when men engaged in transporting9 them from one place to another dip them into water particularly cold. They will also die of suffocation if they be kept in a scanty supply of water. [20] This same remark will hold good for fishes in general; for they are suffocated if they be long confined in a short supply of water, with the water kept unchanged—just as animals that respire are suffocated if they be shut up with a scanty supply of air. The eel in some cases lives for seven or eight years. The river-eel feeds on his own species, on grass, or on roots, or on any chance food found in the mud. Their usual [25] feeding-time is at night, and during the day-time they retreat into deep water. And so much for the food of fishes.
3 · Of birds, such as have crooked talons are carnivorous without exception, and cannot swallow corn even if it be put into their bills; as for instance, the eagle of [592b1] every variety, the kite, the two species of hawks, to wit, the dove-hawk and the sparrow-hawk—and these two hawks differ greatly in size from one another—and the buzzard. The buzzard is of the same size as the kite, and is visible at all seasons of the year. There is also the phene and the vulture. The phene is larger than the [5] common eagle and is ashen in colour. Of the vulture there are two varieties: one small and whitish, the other comparatively large and rather more ashen-coloured. Further, of birds that fly by night, some have crooked talons, such as the night-raven, the owl, and the eagle-owl. The eagle-owl resembles the common owl [10] in shape, but it is quite as large as the eagle. Again, there is the eleus, the Aegolian owl, and the little horned owl. Of these birds, the eleus is somewhat larger than the domestic cock, and the Aegolian owl is of about the same size as the eleus, and both these birds hunt the jay; the little horned owl is smaller than the common owl. All [15] these three birds are alike in appearance, and all three are carnivorous.
Again, of birds that have not crooked talons some are carnivorous, such as the swallow. Others feed on grubs, such as the chaffinch, the sparrow, the batis, the green linnet, and the titmouse. Of the titmouse there are three varieties. The largest [20] is the finch-titmouse—for it is about the size of a finch; the second has a long tail, and from its habitat is called the hill-titmouse; the third resembles the other two in appearance, but is less in size than either of them. Then come the becca-fico, the black-cap, the bullfinch, the robin, the epilais, the midget-bird, and the
golden-crested wren. This wren is little larger than a locust, has a crest of bright red, and is [25] in every way a beautiful and graceful little bird. Then the anthus, a bird about the size of a finch; and the mountain-finch, which resembles a finch and is of much the same size, but its neck is blue, and it lives in the mountains; and lastly the wren and the rook. The above-enumerated birds and the like of them feed either wholly or for the most part on grubs, but the following and the like feed on thistles; to wit, the [593a1] linnet, the thraupis, and the goldfinch. All these birds feed on thistles, but never on grubs or any living thing whatever; they sleep also on the plants from which they derive their food.
There are other insectivorous birds, which live by hunting insects—as for [5] instance, the great and the small pie, which are nicknamed the woodpeckers. These two birds resemble one another in plumage and in note, only that the note of the larger bird is the louder of the two; they both frequent the trunks of trees in quest of food. There is also the greenpie, a bird about the size of a turtle-dove, green-coloured all over, that pecks at the bark of trees with extraordinary vigour, lives [10] generally on the branch of a tree, has a loud note, and is mostly found in the Peloponnèse. There is another bird called the ‘grubpicker’, about as small as the penduline titmouse, with speckled plumage of an ashen colour, and with a poor note; it is a variety of the woodpecker.