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Inside JEB i HOLASPIS GUENTHERI GLIDES But how was the tiny lizard able to remain Inside JEB highlights the key LIKE A FEATHER airborne for so long? Maybe the lizard was developments in The Journal of squashing itself flat while gliding to increase Experimental Biology. Written by its surface area and generate more lift. But science journalists, the short when the team analysed the lizards’ reports give the inside view of trajectories, H. guentheri’s shape did not the science in JEB. change. And when Aerts calculated the amount of lift each lizard generated as they descended, it was clear that H. guentheri was Most lacertid lizards are content scurrying in unable to produce a lift force. The team and out of nooks and crannies in walls and realised that instead of increasing its surface between rocks. However, some have opted area to generate lift, H. guentheri is able to for an arboreal life style. Holaspis guentheri glide because it is so light. The lizard’s leap from branch to branch as they scamper ‘wing loading’ (mass:surface area ratio) was through trees in the African forest. There are the same as that of the gliding gecko even anecdotes that the tiny African lizards (assisted by skin flaps and webbed feet) so can glide. But without any obvious the lizard was able to glide like a feather adaptations to help them to upgrade a leap to because it was so light. a glide, it wasn’t clear whether the reptiles really do take to the air and, if they do, how Curious to find out why H. guentheri is so they remain aloft. Intrigued by all aspects of light, Herrel contacted Renaud Boistel, Paul lacertid locomotion, Bieke Vanhooydonck Tafforeau and Vincent Fernandez at the from the University of Antwerp and her European Synchrotron Radiation Facility to colleagues, Anthony Herrel and Peter Aerts, scan all three lizards’ bodies. Visualising decided to find out whether H. guentheri the animals’ skeletons with X-rays, it was really glide. Recruiting undergraduate Greet clear that H. guentheri’s bones were packed Meulepas to the team, they began filming full of air spaces, making the lizard’s dainty H. guentheri lizards, gliding geckos skeleton feather light for gliding. (Ptychozoon kuhli) and landlocked Podarcis 10.1242/jeb.035519 muralis lacertid lizards as the animals leapt Vanhooydonck, B., Meulepas, G., Herrel, A., Boistel, from a 2m high platform to see if the R., Tafforeau, P., Fernandez, V. and Aerts, P. (2009). African lizards really could glide (p.2475). Ecomorphological analysis of aerial performance in a non-specialized lacertid lizard, Holaspis guentheri. J. Unfortunately, filming the tiny lizards was Exp. Biol. 212, 2475-2482. extremely difficult. Having startled the small animals into leaping off the platform, ENERGETIC BOTTLENECK the team had little control over the animal’s FACTORS IN WINTER WRECKS B direction, and couldn’t guarantee that it was It’s a terrible sight: hundreds of dead parallel to their camera. It was also difficult seabirds washed up on the seashore. These to capture each trajectory with a single catastrophic events occur in the winter and E camera and tricky to get the lighting are known as winter wrecks. No one knows conditions right. But after weeks of why the birds perish, and it is almost persistence the team finally collected impossible to study the animals out in J enough film, as the lizards leapt, to stormy winter seas to find out how they compare their performances. meet their fate. With the birds’ tough life style in mind, Jérôme Fort and David At first, it didn’t look as if the African Grémillet from the CNRS Centre lizard was gliding any better than the P. d’Ecologie Fonctionnelle et Evolutive in e muralis. Both animals were able to cover France decided to try to estimate the horizontal distances of 0.5 m after leaping energetic demands placed on two alcid from the platform, while the gliding gecko species (little auks and Brünnich’s covered distances greater than 1 m, aided by guillemots) by their aquatic lifestyle to find d its webbed feet and skin flaps. But when out whether battling the harsh conditions the team compared the lizards’ sizes, they may simply be too energetically demanding noticed that there was a big difference for the little seafarers (p. 2483). i between the two lacertid lizards. The tiny African reptile only weighed 1.5 g, almost As it is impossible to gain access to the 1/3 of the larger lacertid lizard’s weight and offshore birds in winter to directly measure s 1/10 the gliding gecko’s mass, so Aerts their energy requirements, Fort and calculated how far each lizard would travel Grémillet teamed up with Warren Porter, horizontally if they fell like a stone. This who models the effects of environmental time it was clear that the tiny H. guentheri conditions on terrestrial animals, to estimate n was travelling 0.2 m further than he would the birds’ metabolic demands. Adjusting have expected if it were simply jumping off Porter’s Niche MapperTM computational the platform. Holaspis guentheri was model to take account of the ocean I definitely delaying its descent and landing environment and the birds’ physiology, the more slowly than P. muralis; it was gliding. team included environmental data for two THE JOURNAL OF EXPERIMENTAL BIOLOGY Inside JEB ii regions of the Atlantic Ocean (off than striking fear into their prey’s heart. FULL-UP BLOOD SUCKERS GO Newfoundland and Greenland) occupied by Figuring out which scents simply stink and OFF DINNER little auks and Brünnich’s guillemots. They which scare the life out of an animal is When a blood-sucking Rhodnius prolixus also detailed the plumage, physiology and critical for scientists that want to understand bug settles down to lunch, it is often at risk behaviour of individual birds and calculated the physiology of fear. They have to be sure of being thwacked by its prey; no one likes the animals’ metabolic demands for the that animals are genuinely terrified rather being dined upon. Given the risks that a months from September to March. than simply avoiding a repulsive smell. hungry insect runs when filling up, Aurélie Thomas Endres and Markus Fendt from Bodin and her colleagues Clément Vinauger The results were startling. Both species’ Universität Tübingen decided to test the and Claudio Lazzari wondered whether energy demands were relatively low during effects of two stenches on rats to find out fully fed bugs ignored tempting cues sent the months of September and October, but whether 2,4,5-trimethyl-3-thiazoline (TMT), by their food in a bid to prolong life rocketed by 16–20% in November and derived from fox faeces, produces a genuine (p. 2386). remained high for the rest of the winter. The fear response (p. 2324). team realised that an energy demand of Knowing that hungry bugs respond to vital –1 430kJday for the tiny, 150g little auks and Knowing that rats take evasive action signs, such as exhaled CO2 and warmth, the 1306kJday–1 for the Brünnich’s guillemots when they sniff TMT, Endres and Fendt trio tested hungry and well fed bugs’ must place the animals under enormous tested how young rats reacted to different responses to a jet of CO2 and warmth. All strain as they battle the environment. And concentrations of TMT and another of the insects responded enthusiastically to when the trio converted the birds’ caloric unpleasant smell that rats avoid, butyric the jet of CO2 by approaching it before requirements into the amount of food that acid. Placing a scrap of filter paper dining, but as soon as they had eaten, their each animal would have to find and consume carrying a tiny drop of either TMT or behaviours changed. The males failed to daily, it came out at a colossal 289g of butyric acid in the corner of an arena, the respond to the CO2 jet, wandering in all zooplankton for the little auks (almost twice team filmed the rats’ reactions to the directions, and at first the females and their own body weight) and 547g of fish and smells to find out how much time they larvae were equally unresponsive to the crustaceans for Brünnich’s guillemots (just spent avoiding the unpleasant smells. CO2. However, several days after sucking over half of their body weight). Endres and Fendt found that the rats blood, both the larvae and females began avoided both smells, but the rodents really backing away from the CO2 jet; instead of Fort says ‘For seabirds, this is an energetic disliked visiting the corner that smelled of attracting them, the gas was repelling them. bottleneck’. He explains that as the winter TMT. The animals tolerated a 0.387ϫ10–6 Eventually, after almost 3 weeks and sets in, increased wind speeds, low mol drop of TMT, avoided a 3.87ϫ10–6 another period of disinterest in the gas jet, temperatures and vicious winter storms all mol drop and strongly disliked the large the insects rediscovered their taste for CO2, conspire to raise the birds’ metabolic 38.7ϫ10–6 mol drop while the rats only and started heading towards it again, demands. At the same time food becomes avoided the largest drop of butyric acid presumably in the hope of catching another scarce and more difficult to capture. Coupled (54.7ϫ10–6 mol) and were unaffected by blood meal. with the increase in their energy demands, small drops. So the rats avoided both the birds only carry limited reserves, placing smells but seemed much more sensitive to Curious to find out how the bugs’ them at an increased risk of starvation.

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