Sympetrum 

 dragonfly 

 perches in a 

 Hungarian 

 cemetery. 



SAMPLINGS 



Animal Aqueduct 



Cuddly they're not, but the Texas 

 horned lizard and the Australian 

 thorny devil share more than just prickles. 

 They boast the same remarkable adaptation to their arid home- 

 lands: scale-covered skin that captures water and carries it to the 

 animal's mouth, enabling it to drink when raindrops hit its back or 

 even, in the thorny devil's case, when its belly meets damp sand. 

 Recently, a team led by Wade C. Sherbrooke of the American 

 Museum of Natural History in New York figured out how this weird 

 plumbing system works. 



Using advanced microscopy, the investigators discovered mi- 

 nute ducts beneath the base of the skin scales. The hair-fine ducts 

 connect to form a network that covers the lizard's body and opens 

 up in the corner of the mouth. Sherbrooke and his colleagues 

 think that water, pulled by capillary action, slips under the scales 

 and spreads through the interconnected ducts. The animal, ap- 

 parently by moving its tongue and jaws in a particular way, can 

 draw the water into its mouth and take a sip. 



As their names suggest, the Australian thorny devil and the 

 Texas horned lizard live on opposite sides of the world and are 

 not closely related, and so the water-transporting skin that cloaks 

 both species is a striking example of convergent evolution. 

 (Zoo morphology) — Stephan Reebs 



A Grave Mistake 



Dragonflies congregate at a cemetery in 

 the Hungarian town of Kiskunhalas, 

 perching on twigs and iron rail- 

 ings near polished black tomb- 

 stones. It seems the insects mis- 

 take the horizontal surfaces of the stones 

 for water, say Gabor Horvath of Eotvos 

 University in Budapest and colleagues. 



Still water usually reflects polarized 

 light in a specific pattern, and some water- 

 loving insects use the pattern to locate 

 puddles and ponds. As Horvath's team 

 discovered, reflections from horizontally 

 oriented, polished black gravestones 

 create the same pattern as water does. 

 In several tests at the cemetery, the 

 dragonflies — all members of the genus 

 Sympetrum — showed no interest in matte 

 dark objects or in polished light-colored 

 stones, neither of which reflect polarized 

 light in just the right way. 



Dragonflies mate near water and lay 

 their eggs in it. Horvath's team observed 

 males and females at the cemetery fly- 

 ing in tandem over the black stones, 

 sometimes touching them as if to deposit 

 eggs. The researchers found no eggs on 

 the graves, but the possibility remains 

 that gravestones — and other dark, shiny 

 horizontal surfaces where dragonflies 

 sometimes gather, such as pools of oil and 

 spiffy cars — can act as "ecological traps" 

 for insects attracted to certain patterns of 

 polarized light. (Freshwater Biology) — S.R. 



Texas hon 

 lizard, top 

 Australian 

 devil, righ 

 similarly p 



