African Elephants are the largest and most powerful animals on land. They are very intelligent with complex social lives. Elephants communicate in a low frequency with subtle sounds which humans cannot hear and also by posture and movements of ears and trunk. They use their sensitive and mobile trunks to collect the 150-200 kilograms of plant material a day that they need to consume. To cool themselves they flap huge ears, cooling the blood in superficial blood vessels. They shower themselves with water, mud and sand. Wise old matriarchs lead the herds of females and calves where young are brought up with loving care. Bull elephants roam alone or in small closely knit groups.