Plutarch, De sollertia animalium
Goodwin, Ed.

But why should we admire society in these creatures, when the most savage and most unsociable of all creatures which either lakes, rivers, or the ocean nourishes, the crocodile, shows himself the most sociable and grateful of water monsters in the banquets which he bestows upon the trochilus? For the trochilus is a bird that haunts marshes and rivers, and he guards and watches over the crocodile, not as one that feeds at his table, but as one that lives upon his scraps and leavings only. For when this bird observes the crocodile asleep, and the ichneumon ready to assail him, smeared with mud for the conflict like a wrestler covered with dust, he never leaves crying and pecking him with his beak, till he rouse the drowsy monster. In return of which the crocodile is so tame and gentle towards this bird, that he permits him to enter his yawning chaps, and is pleased with his pecking out and cleansing away with his beak the remainders of the devoured flesh that sticks between his teeth. And when the monster has an inclination to shut his mouth, he gives the bird notice by a gentle lowering of his jaw, nor will he close his chaps till he finds that the bird is flown away. The fish which the Greeks call hegemon (or the captain or leader) is a small fish, in bigness and shape not much unlike a gudgeon, but by reason of the roughness of his scales is said to resemble a bird when she shakes her feathers. This [p. 207] fish always keeps company with one of the huge whales, and swims before him to direct his course, lest he should bruise himself upon the shallows, or fall into any marshy place or narrow haven whence he could not easily get out again. Therefore the whale follows him, as the ship follows the helm, directing his course with confidence. All other things whatever, whether skiff, whether beast or stone, that chance to light into the gaping gulf of the whale's mouth, immediately perish, being swallowed by the monster; but acknowledging his conductor, he receives him and lodges him, like an anchor, safely in his jaws. There he sleeps; and all the while he takes his rest, the whale lies still, as if he were at anchor; and when his guide comes forth again, the whale proceeds, never forsaking him night or day; or if he wander without his leader, the monster shipwrecks, like a vessel cast upon a rock without a helm. And this we saw not long ago near Anticyra, where they report that in former times a whale being cast and putrefying caused a pestilence.

Is it worth while then to compare these observations of community and association with those sympathies which, as Aristotle relates, exist between foxes and serpents because the eagle is an enemy to both? Or with those of the horn-owls with horses, whose dung they love to scrape about the field? For my part I observe no such care of one another in bees and emmets, which, by reason of their multitude, carry on and perfect their work in common, but have no particular care or consideration one of another.