Camels can endure thirst for three days and prefer to drink muddy water
There are two types of camels: Bactrian, which have only one hump but are strong; and Arabian, which have two humps and are more numerous. They hate horses. Camels can endure thirst for three days and prefer to drink muddy water; if only clear water is available, they will stir it up with their feet to muddy it. When they drink, they fill up for both past thirst and for future needs. Some camels are good for carrying burdens, while others are better suited to traveling. Their hoofs do not wear down. They can live for one hundred years, unless they are taken to a foriegn country, where the change of air makes them ill. Female camels are used in war. Camels grow wild with the desire to mate; this desire can be destroyed by castration, which also makes the camel stronger.
Pliny the Elder [1st century CE] (Natural History, Book 8, 26): Camels are found in the East, and are of two kinds: Bactrian, with two humps, and Arabian, with one hump. Both kinds are like oxen in having no teeth in the upper jaw. They live fifty to one hundred years, but are vulnerable to rabies. They are used to carry burdens; they will refuse to carry more than the regulation load. They are also used in battles, but are slower than horses, for which they have an inate hatred. They can travel four days without water; when they find water they drink to quench their thirst and to provide for the future, first stirring up the water with their fore feet. Their strength is increased by denying them sexual intercourse; for this reason both males and females intended for war are gelded.
Isidore of Seville [7th century CE] (Etymologies, Book 12, 1:35): The camel gets its name either from the Greek chamai meaning low and short, because camels lie down while they are being loaded, so they are shorter or lower; or from the Greek chamai (meaning hump) because they have a hump on their back. Most camels come from Arabia. Camels from other lands have one hump, but Arabian camels have two.