Nectar uptake in bats using a pumping-tongue mechanism

Area of Science:

• Zoology
• Biomechanics
• Evolutionary Biology

Background:

• Nectarivory is common in insects but rare and opportunistic in vertebrates.
• Few vertebrate species exhibit specialized nectar-feeding morphologies.
• Nectar-feeding bats display two distinct tongue types: hairy papillae and hairless with lateral grooves.

Purpose of the Study:

• To investigate the distinct nectar-feeding behaviors associated with different bat tongue morphologies.
• To elucidate the fluid uptake mechanisms employed by nectar-feeding bats.
• To understand the evolutionary convergence into the nectar-feeding niche.

Main Methods:

• High-speed video recordings of bats feeding from experimental nectar feeders.
• Comparative analysis of feeding behaviors between bats with grooved and hairy tongues.
• Examination of fluid dynamics and extraction efficiency related to tongue structure.

Main Results:

• Bats with grooved tongues exhibit a novel fluid uptake mechanism, not previously observed in mammals.
• This mechanism involves nectar rising in lateral grooves, likely via tongue deformation and capillary action.
• Bats with hairy tongues utilize conventional sinusoidal lapping movements.
• Nectar extraction efficiency decreased similarly for both tongue types as nectar levels deepened.

Conclusions:

• Convergent evolution has led to distinct nectar-feeding strategies in bats.
• Grooved tongues represent a novel mammalian drinking mechanism involving capillary action and tongue deformation.
• These findings offer insights into fluid mechanics, mammalian feeding adaptations, and ecological niche partitioning.