Megabat evolved early in the lineage of chiropterans. Although echolocation was later lost in family Pteropodidae, bats in the genus "Rousettus" are capable of primitive echolocation through clicking their tongues, and some species have been shown to create clicks similar to those of echolocating bats using their wings. Both echolocation and flight are energetically expensive processes. The nature of the flight and echolocation mechanism of bats allows for creation of echolocation pulses with minimal energy use. Energetic coupling of these two processes is thought to have allowed for both energetically expensive processes to evolve in bats. The loss of echolocation may
Do not feed the animals animals aggressively seeking out food from people, sometimes resulting in injury. Zoos generally discourage visitors from giving any food to the animals. Some zoos, particularly petting zoos, do the opposite and actively encourage people to get involved with the feeding of the animals. This, however, is strictly monitored and usually involves set food available from the zookeepers or vending machines, as well as a careful choice of which animals to feed, and the provision of hand-washing facilities to avoid spreading disease. Domestic animals such as sheep and goats are often permitted to be fed, as are giraffes. In national parks