To complete this lesson, complete the following tasks:
- Hear the lesson prelection.
- Study the lesson for mastery.
- Complete the lesson assessment.
1. Some animals have feet, others have none; of the former some have two feet, as mankind and birds only; others have four, as the lizard and the dog; others, as the scolopendra and bee, have many feet; but all have their feet in pairs.
2. And among apodous swimming animals some have fins, as fish; and of these some have two fins in the upper and two in the lower part of their bodies, as the chrysophys and labrax; others, which are very long and smooth, have only two fins, as the eel and conger; others have none at all, as the lamprey and others, which live in the sea as serpents do on land, and in like manner swim in moist places; and some of the genus selache, as those which are flat and have tails, as the batos and trygon, have no fins; these fish swim by means of their flat surfaces; but the batrachus has fins, and so have all those fish which are not very thin in proportion to their width.
3. But the animals which have apparent feet, as the cephalopods, swim both with their feet and fins, and move quickly upon the hollow parts of their bodies, as the sepia, teuthis, and polypus; but none of them can walk except the polypus. Those animals which have hard skins, as the carabus, swim with their hinder parts, and move very quickly upon their tail, with the fins which are upon it, and the newt both with its feet and tail, and (to compare small things with great) it has a tail like the glanis.
4. Some winged animals, as the eagle and the hawk, are feathered; others, as the cockchafer and the bee, membranaceous wings; and others, as the alopex and the bat, have wings formed of skin. Both the feathered and leather winged tribes have blood; but the insects, which have naked wings, have no blood. Again, the feathered and leather winged animals are all either bipeds or apodous, for they say that there are winged serpents in Ethiopia .
5. The feathered tribe of animals is called birds; the other two tribes have no exact names. Among winged creatures without blood some are coleopterous, for they have elytrą over their wings, as the cockchafer and the beetles, and others are without elytra. The animals of this class have either two or four wings. Those with four wings are distin guished by their greater size or a caudal sting. The diptera are either such as are small, or have a sting in their head. The coleoptera have no sting at all; the diptera have a sting in their head, as the fly, horse-fly, gad-fly, and gnat.
6. All bloodless animals, except a few marine species of the cephalopoda, are smaller than those which have blood. These animals are the largest in warm waters, and more so in the sea than on the land, and in fresh water. All creatures that are capable of motion are moved by four or more limbs. Those with blood have four limbs only, as man has two hands and two feet . Birds have two wings and two feet; quadrupeds and fishes have four feet or four fins. But those animals which have two wings or none at all, as the serpent, are nevertheless moved by four limbs; for the bendings of their body are four in number, or two when they have two wings.
7. Those bloodless animals which have more than four feet, whether furnished with feet or wings, always have more than four organs of locomotion, as the ephemera, which has four feet and four wings; and in this it not only agrees with its peculiar manner of life, from which also it derives its name, but also that it is winged and four-footed; and all creatures, whether they have four feet or many feet, move in the same direction, for they all move in the long way of their bodies. All other animals have two leading feet, the crab alone has four.
Source: Aristotle, History of Animals; translated by Richard Cresswell, M.A. (1862)