The location of butterfly ears on their wings was discovered in 1912. Today, new research has discovered a clever structure in those ears that potentially makes it able to distinguish between high and low pitch sounds.
The Blue Morpho butterflies, which are native to Central and South America, are more famous for their amazing wing colorations than the sensitivity of the ears on their wings. But their simple ear sits at the base of the wing.
An oval-shaped tympanal membrane, with an unusual dome in the middle, is attached directly to sensory organs and is responsible for converting sound waves into signals that can be picked up by nerve cells.
Using a tiny laser beam, lead researcher Katie Lucas scanned the surface of the membrane while it was in action, and found that lower pitch sounds cause vibrations only in a part of the outer membrane while higher pitch sounds caused the entire membrane to vibrate.
The structure of the membrane could mean the butterfly can hear a greater range of pitches, which as Katie Lucas and her colleagues postulate may enhance the abilities of these butterflies to listen for birds.
The team suggests that sensitivity to lower pitch sounds may detect the beating of birds' wings, while higher pitches may tune into birdsong.