"Bats have big ears, furry bodies and wings like leather. They are nocturnal mammals. This means they sleep in caves and attics during the day and fly out to feed at night-time.
Bats are the only mammals that can fly. They are very fast and aerobatic. When they chase after insects, they twist and turn in mid-air. Bats use sound to catch insects in the darkness. They spent out- high-pitched squeals that humans cannot hear. The echoes that bounce back tell the bats exactly where they find their prey.
Flying foxes or fruit bats are large bats that live in tropical Africa and Asia. They mainly eat fruit. Flying foxes are important because they help to spread the pollen of many plants."
What is the main idea of the second paragraph?