Many plants lure pollinators to their flowers with diverse colours and patterns, but Marcgravia evenia (pictured) has evolved to attract pollinators that rely on sound rather than sight. The Cuban rainforest vine grows a deep cup-shaped leaf above its flowers that creates a distinct echo for nectar-feeding bats.

Ralph Simon at the University of Ulm in Germany and his colleagues analysed the leaf's acoustic properties and found that its unique shape produces a strong, constant echo across a range of sound-source angles. They then trained bats to seek a feeder hidden in artificial foliage. The animals found feeders topped with the cup shape in an average of 12 seconds — around half the time it took them to locate unadorned feeders or those under other leaf shapes.