Blind Cavefish Froze Its Internal Clock to Save Energy

By Elizabeth Palermo, Staff Writer | September 24, 2014 02:13pm ET

Some creatures will go to great lengths just to save a little energy. Take the blind Mexican cavefish; this super-efficient animal uses almost 30 percent less energy to survive than its counterparts in surface waters, and it accomplishes this in a rather interesting way, a new study suggests.

The blind Mexican tetra or cavefish (Astyanax mexicanus) saves energy by forgoing circadian rhythms, according to researchers at Lund University in Sweden. Sometimes referred to as an internal clock, circadian rhythms help many organisms — including animals, plants, fungi and even certain bacteria — coordinate their behavior and physiology with the day-night cycle, according to study researcher Damian Moran, a postdoctoral student in the Lund University department of biology.

This clock provides one of its most important functions by controlling metabolism, or the chemical reactions involved in maintaining healthy cells and breaking down molecules to gain energy. Circadian rhythm helps ensure these reactions occur in advance of when an organism will most need energy, Moran told Live Science.

Continued ...

Dormice 'take naps to aid chances of survival'

2nd July 2014

By Victoria Gill

Science reporter, BBC News, Manchester

The notoriously sleepy dormouse may be even sleepier than previously thought and researchers say naps help the animals survive until hibernation.

Researchers in Vienna found that when less food was available, garden dormice used a short sleep-like state called torpor to save energy.

The animals also appear to use torpor when the weather is colder.

They presented their findings at the Society for Experimental Biology's annual meeting in Manchester, UK.

Lead researcher Dr Sylvain Giroud from the University of Veterinary Medicine, Vienna compared dormice that had unlimited supplies of food with those that were fasted on alternate days.

The food-restricted dormice used torpor more frequently and entered the sleep-like state for longer than those animals that were able to feed freely.

While they are in this state, their metabolic rate slows and their body temperature is reduced, which saves energy. This allows the animals to store more body fat, which is crucial for their winter survival.

"This shows how the wild mice cope with the unpredictability of food," explained Dr Giroud.

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Bats Save Energy by Drawing in Wings On Upstroke

ScienceDaily (Apr. 11, 2012) — Bat wings are like hands: meaty, bony and full of joints. A new Brown University study finds that bats take advantage of their flexibility by folding in their wings on the upstroke to save inertial energy. The research suggests that engineers looking at flapping flight should account for wing mass and consider a folding design.Whether people are building a flying machine or nature is evolving one, there is pressure to optimize efficiency. A new analysis by biologists, physicists, and engineers at Brown University reveals the subtle but important degree to which that pressure has literally shaped the flapping wings of bats.

The team's observations and calculations show that by flexing their wings inward to their bodies on the upstroke, bats use only 65 percent of the inertial energy they would expend if they kept their wings fully outstretched. Unlike insects, bats have heavy, muscular wings with hand-like bendable joints. The study suggests that they use their flexibility to compensate for that mass.

"Wing mass is important and it's normally not considered in flight," said Attila Bergou, who along with Daniel Riskin is co-lead author of the study that appears April 11 in theProceedings of the Royal Society B."Typically you analyze lift, drag, and you don't talk about the energy of moving the wings."

The findings not only help explain why bats and some birds tuck in their wings on the upstroke, but could also help inform human designers of small flapping vehicles. The team's research is funded by the U.S. Air Force Office of Sponsored Research.

"If you have a vehicle that has heavy wings, it would become energetically beneficial to fold the wings on the upstroke," said Sharon Swartz, professor of ecology and evolutionary biology at Brown. She and Kenneth Breuer, professor of engineering, are senior authors on the paper.

Contined:  http://www.sciencedaily.com/releases/2012/04/120411084133.htm

Aye-aye lemur 'heats up' its special foraging finger

Madagascar's mysterious aye-aye warms up its extra-long finger when searching for dinner, scientists have found.

The lemur, the world's largest nocturnal primate, taps its specialised middle finger on tree trunks to find nutritious beetle larvae.

Studying thermal images, researchers found that the digit was colder than the others but warmed by up to 6C during foraging. Scientists suggest that the aye-aye saves energy by keeping the digit
cool. The findings are published in the International Journal of Primatology.

The team from Dartmouth University in New Hampshire, US, wanted to investigate the surface temperature of sensitive structures. The aye-aye's unusual middle finger has already been found to be super-sensitive to vibrations, so provided the perfect subject for their study.

"It was striking to see how much cooler the third digit was while not in use and how quickly it warmed to [match] the other digits when engaged in an active foraging task," said graduate student Gillian Moritz, who carried out the study under the guidance of her supervisor, Dr Nathaniel Dominy.

Continued: http://www.bbc.co.uk/nature/16577537