This Bat Has the Longest Tongue Among Mammals and It Hides It Inside Its Chest

A flower's hidden nectar may have helped drive the evolution of one of the strangest tongues in the mammalian world.

A bat barely the size of a mouse has evolved a tongue that stretches farther than its entire body. However, the real surprise lies beneath its fur. 

Instead of growing a longer snout to accommodate its extraordinary tongue, Anoura fistulata stores part of it inside its chest, between the heart and breastbone. 

“This relative tongue protrusion is greater than that seen in any other mammal, and is second only to the chameleon among the vertebrates,” Nathan Muchhala, an evolutionary ecologist who discovered and studied A. fistulata in detail, notes in one of his research articles. 

This unusual adaptation lets the bat reach nectar hidden deep inside a flower that other nectar-feeding bats cannot access—and that’s not all.

Scientists believe that the bat’s adaptation may have also influenced the evolution of the flower it visits

A tongue that breaks the usual rules

The tube-lipped nectar bat was discovered in 2003 in the cloud forests of Ecuador’s Andes, where it lives alongside two related species, Anoura caudifer and Anoura geoffroyi. Scientists found that A. fistulata could extend its tongue roughly twice as far as its relatives.

While the other two species extended their tongues to approximately 36.7 and 39.3 millimeters, respectively, A. fistulata reached 84.9 millimeters. This is about 150 percent of its body length, making it the longest tongue relative to body size among mammals.

This tongue is specialized for collecting nectar. When it reaches the bottom of a flower, hair-like structures called papillae extend outward from its tip, increasing its surface area and helping collect nectar.

However, an unusually long tongue would create serious biomechanical problems for any other species. In most nectar bats, tongue length is closely linked to the length of the palate and jaw. Extending the tongue generally requires a longer mouth structure, which can affect biting mechanics.

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But for A. fistulata, evolution appears to have found a different solution.

How the tongue reaches into the chest

To understand the mechanism behind the bat’s long tongue, Muchhala performed an interesting experiment. He captured some individuals and trained them to drink sugared water from a modified straw measuring six millimeters in diameter using their tongues. 

He then examined the animal’s anatomy, and what he observed was completely different than what he himself imagined.

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“I had all sorts of theories, such as perhaps the tongue folded up inside, or coiled, or maybe its lower lip was critical somehow,” Mucchala said.

In reality, the tongue’s base passes backward through the neck and into the chest cavity. A sleeve of tissue called a glossal tube surrounds this section, positioning the tongue’s base between the heart and sternum.

When retracted, this portion remains stored inside the chest. This is how the tongue is able to extend up to three times its stored length, reaching far beyond the mouth without requiring an equally elongated snout.

“Instead of evolving a longer jaw, it pushed the base of the tongue back and into the rib cage,” Muchhala added.

A longer snout can compromise biting mechanics because of the way the jaw functions as a lever. A short snout may therefore help the bat retain feeding flexibility, although no research work has directly established this mechanical advantage. 

A flower made for one unusual pollinator

A. fistulata’s extraordinary tongue pointed researchers toward an equally unusual flower named Centropogon nigricans. Its funnel-shaped corolla extends approximately 8–9 centimeters, placing the nectar deep inside a narrow floral tube.

Over 129 nights of mist-netting between 2003 and 2005, Muchhala and his team captured 21 A. fistulata, 46 A. geoffroyi and 38 A. caudifer. Pollen from C. nigricans was found only on A. fistulata, suggesting that the other bats could not reach the flower’s nectar.

Researchers also videotaped 12 flowers for 55 hours during the day and night. Ten bats visited the flowers, but A. fistulata was the only bat observed reaching the nectar and pollinating the plant.

As the bat feeds, pollen accumulates on its head and can be transferred to another flower. Muchhala explained how the flower’s long tube affects this process.

“It turns out that longer tubes make a bat lift its head up more during a visit, which in turn causes more pollen to get dumped onto the animal’s head,” Muchhala told National Geographic.

Specialization on a single pollinator is extremely rare among flowering plants. Therefore, this relationship between C. nigricans and A. fistulata offers a possible example of reciprocal evolutionary adaptation (also called coevolution), a process where one species may influence the evolution of another species.

Different animals, different diets, but same tongue problem

Muchhala described the possibility of coevolution, but his study did not establish how the two species evolved together over time.

Further studies should focus on comparing tongue lengths among A. fistulata populations living in different regions. If tongue lengths corresponded to local flower lengths, this could provide stronger evidence of coevolution.

Interestingly, A. fistulata isn’t the only mammal with a glossal tube. Pangolins, which feed on ants and termites, have developed a similar structure to accommodate their highly protrusible tongues.

“Pangolins (scaly anteaters) also have a glossal tube, despite their different diets.” Muchhala said. This suggests that “ant-eating and nectar-feeding animals face similar evolutionary pressures for highly protrusible tongues, and pangolins and A. fistulata have independently converged on a similar solution,” he added. 

Despite their different diets and body shapes, both animals have evolved a way to make room for an unusually long tongue. This shows how evolution can reshape the internal anatomy of organisms to overcome physical limitations.