Taken from the link below:

http://bestiary.ca/beasts/beast146.htm

Sources (chronological order)

Herodotus [5th century BCE] (History, book 2): The following are the peculiarities of the crocodile:- During the four winter months they eat nothing; they are four-footed, and live indifferently on land or in the water. The female lays and hatches her eggs ashore, passing the greater portion of the day on dry land, but at night retiring to the river, the water of which is warmer than the night-air and the dew. Of all known animals this is the one which from the smallest size grows to be the greatest: for the egg of the crocodile is but little bigger than that of the goose, and the young crocodile is in proportion to the egg; yet when it is full grown, the animal measures frequently seventeen cubits and even more. It has the eyes of a pig, teeth large and tusk-like, of a size proportioned to its frame; unlike any other animal, it is without a tongue; it cannot move its under-jaw, and in this respect too it is singular, being the only animal in the world which moves the upper-jaw but not the under. It has strong claws and a scaly skin, impenetrable upon the back. In the water it is blind, but on land it is very keen of sight. As it lives chiefly in the river, it has the inside of its mouth constantly covered with leeches; hence it happens that, while all the other birds and beasts avoid it, with the trochilus it lives at peace, since it owes much to that bird: for the crocodile, when he leaves the water and comes out upon the land, is in the habit of lying with his mouth wide open, facing the western breeze: at such times the trochilus goes into his mouth and devours the leeches. This benefits the crocodile, who is pleased, and takes care not to hurt the trochilus. ( Rawlinson translation)