Megabat long, thus smaller than some microbats, for example, the Mauritian tomb bat. The largest attain a wingspan of , and weigh as much as . 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). Megabats make up the only family (Pteropodidae) in order Chiroptera that is not capable of laryngeal echolocation. Echolocation and flight
Echolocation jamming produce ultrasonic clicks in response to the echolocation calls bats use while attacking prey. For most species of tiger moth these clicks warn bats that the moths have toxic compounds that make them distasteful. However, the tiger moth "Bertholdia trigona" produces clicks at a very high rate (up to 4,500 per second) to jam bat echolocation. Jamming is the most effective defense against bats ever documented, with jamming causing a ten-fold decrease in bat capture success in the field. The possibility that moths jam bat echolocation arose with an experiment report published in 1965 by Dorothy Dunning and Kenneth Roeder.