Extreme Tongue: Bat excels at saying ‘Aah’

The new mammalian champ for sticking out its tongue is a small bat from the Andes.

LONG DRINK. A tube-lipped nectar bat from Ecuador sticks out its tongue to drink from a glass cylinder. Between sips, the lower part of the tongue will retract into a sheath that runs from the back of the bat’s mouth down into its chest (inset diagram) M. Cooper; (inset) Muchhala

The tube-lipped nectar bat zaps out a skinny tongue that can extend a distance of 1.5 times its body length, reports Nathan Muchhala of the University of Miami in Coral Gables, Fla. He says that among all vertebrates, only chameleons can top that, reaching out their tongues to twice their body length.

The nocturnal bat’s tongue extends from an attachment point within the animal’s ribcage. Tongues of most animals arise just at the back of their jaws.

Muchhala was studying pollination in cloud forests in the Ecuadorian Andes when he realized that one of the species of nectar-sipping bats that he had netted hadn’t been described by scientists. Last year, Muchhala and his colleagues named it Anoura fistulata.

Among its unusual features is a long, pointy lower lip with a groove in it. At a flower, the tongue shoots out along the groove and then retracts several times within half a second.

To measure tongue extension, Muchhala encouraged bats to sip sugar water from drinking straws. He started with test tubes but switched when the small, agile bats plunged in up to their shoulders. Other local nectar bats reached down 4 cm. The new species more than doubled that depth, Muchhala reports in the Dec. 7 Nature. “I was amazed,” he says.

By studying newly identified museum specimens, Muchhala found that the prodigious tongue attaches within a tube of tissue that originates in the bat’s chest between the sternum and the heart and extends to the back of the mouth. Circular muscles within the tongue tighten to rapidly increase its length.

Some of the pollen grains that Muchhala collected from the bats’ fur came from Centropogon nigricans, a pale-green, trumpet-shaped flower. Nectar collects at the bottom of these blossoms, which average about the length of the tube-lipped bat’s tongue extension.

When Muchhala videotaped such flowers, day and night, for more than a week, bats were the only visitors. He never found the flower’s pollen on other bat species, so he proposes that only tube-lipped bats pollinate that flower.

Other tropical plants cater to single pollinators, notes Scott Mori of the New York Botanical Garden. Those flowers tend to be more specialized than their pollinators, which will visit other flowers after their private nectar reserves have been depleted.

Bat systematist Nancy Simmons of the American Museum of Natural History in New York City welcomes the report of the new tongue structure as “a fabulous discovery.” She says that anteaters are the only other animals that she knows to have tongues in their chests. Other observers have reported that scaly anteaters extend their tongues about 50 percent of their body length.

The anteaters’ supertongues probe ant nests, which present a problem similar to that posed by deep flowers. Simmons says that the anteaters and bats independently evolved tongues that met that challenge.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.

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