Most fruit bats are larger than insectivorous bats or Microchiroptera, however there are a number of small fruit bats also. The smallest species is 6 cm (2.4 in) long and thus smaller than some microbats, for example, the Mauritian tomb bat. The largest attain a wingspan of 1.7 m (5.6 ft), weighing in at up to 1.6 kg (3.5 lb). Most fruit bats have large eyes, allowing them to orient themselves visually in twilight and inside caves and forests.
Their sense of smell is excellent. In contrast to the microbats, the fruit bats do not use echolocation (with one exception, the Egyptian fruit bat Rousettus egyptiacus, which uses high-pitched tongue clicks to navigate in caves).
Loss of Echolocation Edit
Fruit bats make up the only family (Pteropodidae) in order Chiroptera that is not capable of laryngeal echolocation. Echolocation and flight 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 tongue, 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 for bats. 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 be due to the uncoupling of flight and echolocation in megabats. The larger average body size of megabats compared to echolocating bats suggests that a larger body size disrupts the flight-echolocation coupling and made echolocation too energetically expensive to be conserved in megabats.
Behavior and Ecology Edit
Fruit bats mostly roost in trees and shrubs. Only those that possess echolocation venture into the dark recesses of caves. Because they eat fruit, some megabat species are unpopular with orchard owners. Megabats are frugivorous or nectarivorous, i.e., they eat fruits or lick nectar from flowers. Often, the fruits are crushed and only the juices are consumed. The teeth are adapted to bite through hard fruit skins.
Frugivorous bats aid the distribution of plants (and therefore forests) by carrying the fruits with them and spitting the seeds or eliminating them elsewhere. Nectarivores actually pollinate visited plants. They bear long tongues that are inserted deep into the flower; pollen passed to the bat is then transported to the next blossom visited, thereby pollinating it. This relationship between plants and bats is a form of mutualism known as chiropterophily. Examples of plants that benefit from this arrangement include the baobabs of the genus Adansonia and the sausage tree (Kigelia).