Chameleon's tongue gives up secrets

By Helen BriggsBBC News

20 April 2016

Scientists have built a mathematical model to explain the secrets of the chameleon's extraordinary tongue.

It took more than 20 equations to capture mathematically how the reptile's tongue unravels at very high speed to snare insects.

The model explains the mechanics of the animal's tongue and the inherent energy build-up and rapid release.

British researchers say the insights will be useful in biomimetics - copying from nature in engineering and design.

"If you are looking at the equations they might look complex but at the heart of all of this is Newton's Second Law - the sort of thing that kids are learning in A-Levels, which is simply that you're balancing forces with accelerations," explained Derek Moulton, associate professor of mathematical biology at Oxford University.

He added: "In mathematical terms, what we've done is we've used the theory of non linear elasticity and captured the energy in these various tongue layers and then passed that potential energy to a model of kinetic energy for the tongue dynamics."

The chameleon is a reptile with many distinctive features.

Its feet have two toes facing forward and two facing backwards, like a bird; it can grasp objects with its tail; it can change colour and its tongue is among the fastest on Earth.

The chameleon's tongue is able to extend to twice the length of the body while unravelling telescopically.

Past research has shown if the tongue were a car, it could accelerate from 0 to 60 mph in one hundredth of a second.

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Frog tongues: Sticky strips of pure muscle

Date: October 1, 2015

Source: Christian-Albrechts-Universitaet zu Kiel

Scientists from the Functional Morphology and Biomechanics research group at Kiel University have shown, for the first time, what happens when a frog's tongue makes contact with a surface. They discovered similarities to conventional adhesive tape. Like sticky tape, the tongues form lots of little threads (fibrils) when being removed from a surface, which break one at a time before the contact disconnects.

"We got horned frogs to spit their tongues towards a cricket, which was placed behind a sheet of glass," said Dr Thomas Kleinteich from the Zoological Institute to describe the experiment. The glass was connected to a light source which lit up the places the tongue came into contact with. The researchers then filmed these lit areas using a high-speed camera with a time resolution of 0.5 milliseconds (half of a thousandth of a second). This enabled them to observe exactly how the contact formed and then disconnected again.

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Nectar-Slurping Bat Tongues Move Like Human Bowels

by Charles Q. Choi, Live Science Contributor | September 25, 2015 02:08pm ET

Tongue waggles resembling bowel movements could help some bats drink flower nectar, researchers say.

Many insects rely on flower nectar as their main source of food, and have specialized mouthparts to siphon the sweet liquid. A few vertebrates — including birds such as hummingbirds, and mammals such as the honey possum — also have specialized nectar-feeding mouthparts.

Bats make up the largest group of specialized nectar-feeding mammals. These flying beasts often have tongues that are longer than their bodies. However, while most of these species have hairy tongues, some have nearly hairless tongues covered with grooves that stretch from left to right. Until recently, scientists did not know how these differences influence how the bats slurp up nectar.

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To learn more about these bat tongues, scientists used high-speed cameras to watch bats trained to drink nectar from glass tubes containing honey water in the lab. They experimented with Pallas' long-tongued bat (Glossophaga soricina), which has a bristly tongue, and the orange nectar-feeding bat Lonchophylla robusta, which has a grooved tongue.

Flower declines shrink bee tongues

Date:September 24, 2015

Source:American Association for the Advancement of Science

Climate-related changes in flower diversity have resulted in a decrease in the length of alpine bumble bees' tongues, a new study reports, leaving these insects poorly suited to feed from and pollinate the deep flowers they were adapted to previously. The results highlight how certain mutually beneficial ecological partnerships can be lost due to shifts in climate.

Many co-evolved species have precisely matched traits; for example, long-tongued bumble bees are well adapted for obtaining nectar from deep flowers with long corolla tubes. Recent studies suggest long-tongued bumble bees are declining in number. To better understand why, Nicole Miller-Struthman et al. studied several high-altitude sites in Colorado where two species of long-tongued alpine bumble bee live.

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Gigantic whales have stretchy 'bungee cord' nerves

Date:May 4, 2015

Source:University of British Columbia

Summary:Biologists have discovered a unique nerve structure in the mouth and tongue of rorqual whales that can double in length and then recoil like a bungee cord. The stretchy nerves explain how the massive whales are able to balloon an immense pocket between their body wall and overlying blubber to capture prey during feeding dives.

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Why do snakes flick their tongues?

31st July 2014

41 minutes ago by Andrew Durso

Many people think a snake's forked tongue is creepy. Every so often, the snake waves it around rapidly, then retracts it. Theories explaining the forked tongues of snakes have been around for thousands of years. Aristotle reasoned that it provided snakes with "a twofold pleasure from savours, their gustatory sensation being as it were doubled".

Italian astronomer Giovanni Hodierna thought snake tongues were for cleaning dirt out of their noses. Some 17th century writers claimed to have watched snakes catch flies or other animals between the forks of their tongues, using them like forceps. It is a common myth even today that snakes can sting you with their tongues. But none of those hypotheses is likely.

Most animals with tongues use them for tasting, to clean themselves or others, or to capture or manipulate their prey. A few, including humans, also use them to make sounds. Snakes do not use their tongues for any of these things. Over the past 20 years, Kurt Schwenk, an evolutionary biologist at the University of Connecticut, has been working on understanding the function of snake tongues, and "smelling" is the closest description of what snakes do with their tongues.

Read more at: http://phys.org/news/2014-07-snakes-flick-tongues.html#jCp

For bees and flowers, tongue size matters

Date:

July 15, 2014

Source:

Ecological Society of America

Summary:

When it comes to bee tongues, length is proportional to the size of the bee, but heritage sets the proportion. Estimating this hard to measure trait helps scientists understand bee species' resiliency to change.

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Bats Use Blood to Reshape Tongue for Feeding

May 6, 2013 — Brown University scientists have found that a species of bat uses blood flow to reshape its tongue while feeding. The quick dynamic action makes the tongue an effective "mop" for nectar and could even inspire new industrial designs. 

(Credit: Cally Harper in the Brainerd-Swartz Lab/Brown University) 

Nectar-feeding bats and busy janitors have at least two things in common: They want to wipe up as much liquid as they can as fast as they can, and they have specific equipment for the job. A study in the Proceedings of the National Academy of Sciences describes the previously undiscovered technology employed by the bat Glossophaga soricina: a tongue tip that uses blood flow to erect scores of little hair-like structures exactly at the right time to slurp up extra nectar from within a flower. 

The bat's "hemodynamic nectar mop," as the paper dubs the tongue tip, features speed and reliability that industrial designers might envy, said lead author Cally Harper, a graduate student in the Department of Ecology and Evolutionary Biology at Brown University. As a matter of what nature can evolve, she said, the tongue tip is surprisingly clever. 

"Typically, hydraulic structures in nature tend to be slow like the tube-feet in starfish," Harper said. "But these bat tongues are extremely rapid because the vascular system that erects the hair-like papillae is embedded within a muscular hydrostat, which is a fancy term for muscular, constant-volume structures like tongues, elephant trunks and squid tentacles." 

In other words, the bat's cylindrical tongue has a mesh of muscle fibers that contract so that the tongue becomes thinner but longer (extending farther into the flower). The discovery reported in the paper is that the same muscle contraction simultaneously squeezes blood into the tiny hair-like papillae. 

Continued: http://www.sciencedaily.com/releases/2013/05/130506181448.htm