Category: Living World

Watch This: Cicadas Kill Bacteria with Structures on Their Wings

By Breanna Draxler | March 5, 2013 10:42 am

Clanger or clear wing cicada (Psaltoda claripennis). Image courtesy of Arthur Chapman/Flickr

Cicadas don’t use antibacterial wing sanitizer, so how do these insects keep their wings free of bacteria? Hint: it’s structural.

The wings of the Clanger cicada kill certain bacteria by ripping their cell membranes. A pattern of pillar-like nanostructures on the wings’ surface put pressure on the bacterial cell membrane, causing it to stretch and eventually tear. In a study published in Biophysical Journal in February, researchers modeled this process for the first time. They say this is the first example of a species being able to kill bacteria with a physical structure alone.

Replicating this physical structure in bio-inspired synthetic design could eventually lead to the production of antibacterial surfaces that kill bacteria on contact. Watch the video to see a magnified rendering of how the nano-pillars lead to a bacterial cell’s demise.

Video footage courtesy of Sergey Pogodin et al/Biophysical Journal

“Triple Sun [Nonimx]” music courtesy of Coil/FreeMusicArchive.com

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CATEGORIZED UNDER: Living World, Technology, Top Posts

Fossils Reveal Four New Species of Ancient Whales

By Breanna Draxler | February 19, 2013 8:09 am

These are the teeth of an undescribed, new species of toothed baleen whale in the genus Morawanocetus, from Orange County, California. Image courtesy of Meredith Rivin, Dr. John D. Cooper Archaeological and Paleontological Center

Paleontologists in California announced this week that fossils excavated in the early 2000s represent four new species of ancient whales. The toothed baleen whales apparently stuck around longer than scientists once thought, and they may hold clues about how and when whales evolved from toothy giants to the baleen-equipped beasts we see today.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

Anti-Anxiety Drug in Water System Changes Fish Behavior

By Gemma Tarlach | February 14, 2013 1:39 pm

Shoaling perch. Image courtesy of Bent Christensen.

“Must be something in the water” isn’t just a line from the opening minutes of a horror movie.

New evidence confirms fears that animals’ behavior can be altered by medication inadvertently introduced into their habitats via our sewage systems.

In a study published today Swedish researchers report that fish given Oxazepam, an anxiety-moderating drug for humans, became less social and more aggressive. Researchers administered the drug to wild perch in the lab in amounts equivalent to levels found in local rivers and streams.

The dosed fish showed a number of behavioral changes, notably in their willingness to leave familiar and “safe” surroundings in favor of exposed, potentially dangerous areas. The fish treated with the drug also distanced themselves from other perch. These antisocial fish ate faster than normal, which, in the wild, could disrupt the established food chain.

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CATEGORIZED UNDER: Environment, Living World, Top Posts
MORE ABOUT: pharmaceuticals, sewage

Urban Light Causes Birds to Bloom Early

By Breanna Draxler | February 14, 2013 12:02 pm

European Blackbird (turdus merula). Image courtesy of IbajaUsap / shutterstock

City lights at night make pretty views from space, but they’re not so good for sleeping. To overcome a messed up inner clock, many urban dwellers have learned to use light-blocking curtains or eye masks. But people aren’t the only ones who have to adjust to this unnatural illumination. Blackbirds, too, are exposed to this nighttime glow, and it actually makes them mature and moult sooner.

Reproduction is a seasonal ritual for birds, hence the term mating season, and they take their cues from their environment. Light is one of the factors that impacts the initiation of sexual maturity, and being exposed to light during the night appears to throw off this natural cycle.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

Salmon Navigate Home Using Earth’s Magnetic Fields

By Breanna Draxler | February 8, 2013 2:51 pm

Couple of sockeye salmon just prior to spawning. image courtesy of Vasik Olga / shutterstock.

Sockeye salmon put on a lot of miles during their short life. From the freshwater riverbeds where they hatch and spend their first couple years, juvenile salmon travel some 4,000 miles to the ocean where they fatten up for two years before turning around and retracing their steps.

But salmon can’t leave actual footprints, nor do they have the luxury of dropping waterproof bread crumbs so they can find their way back home. Scientists have long suspected that these big fish instead use the Earth’s magnetism to orient their inner compass. A recent study of 56 years’ worth of migration data presents pretty convincing evidence for this geomagnetic hypothesis and how it works.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

Insects Clean Antennae to Sharpen Sense of Smell

By Breanna Draxler | February 5, 2013 10:16 am

Image courtesy of Barnaby Chambers / shutterstock

Insects constantly clean their antennae, even when they appear to be clean. A group of researchers decided that the phenomenon warranted a closer look, and they used American cockroaches to see what was going on. It turns out that the obsessive behavior is actually the way many insects keep their sense of smell sharp—though it may also lead to their eventual demise.

Cockroaches use their front legs to stick their antennae in their mouths and essentially lick them clean. In the lab, researchers prevented the cockroaches from performing this self-cleaning ritual to see what would happen. A waxy substance accumulated on the insects’ antennae, which turned out to be a mix of environmental pollutants and cuticular hydrocarbons. The latter is a fatty substance the cockroach produces as a sort of moisturizer to prevent water loss through its antennae. After just one day, the non-grooming cockroaches had amassed three to four times as much of the wax as compared to the control group.

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: grooming, insects, senses

How Owls Rotate Their Heads So Far Without Snapping Their Necks

By Breanna Draxler | February 1, 2013 12:22 pm

A baby barn owl demonstrates the natural neck flexibility of the owl. Researchers studied snowy, barred, and great horned owls. Image courtesy of marilyn barbone / shutterstock.

Most animals, humans included, can only turn their heads so far without snapping their necks or causing a stroke. But owls can rotate their necks 270 degrees—an impressive ¾ of a full rotation—without causing any harm. Owls have unmoving eyeballs, so neck rotation is necessary for the animal to have any sort of peripheral vision. How can owls pull it off without cutting off the blood supply to their brains?

For the first time, researchers at Johns Hopkins think they may have an explanation. By dissecting dead owls, the researchers pinpointed adaptations in the vertebrae and blood vessels that they think allow the owl to achieve such a feat. Their illustrated results were published in Science today, and won first prize for posters in the NSF/Science visualization challenge.

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CATEGORIZED UNDER: Living World, Top Posts

Domestic Cats Kill More Small Wildlife Than Any Other Human Activity

By Breanna Draxler | January 29, 2013 12:59 pm

Image courtesy of Matt Valentine / shutterstock

Domestic cats are known killers, and when let loose they can do real predatory damage. Cats (Felis catus) can wipe out entire populations of native birds and small mammals such as mice, squirrels and rabbits when introduced to island environments. Eradication efforts have historically been implemented to remove these non-native predators from islands.

A new study shows that domestic cats can wreak havoc on the mainland as well. Researchers say un-owned cats kill far more birds and mammals than previously thought, making them the greatest human-related cause of these wildlife deaths in the United States.

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CATEGORIZED UNDER: Environment, Living World, Top Posts
MORE ABOUT: birds, cats, mammals, mortality

Dung Beetles Protect Their Dung Balls By Following the Milky Way

By Breanna Draxler | January 25, 2013 8:09 am

 

In the study, African dung beetles (S. satyrus) wore “caps” to block their view of the sky. Image courtesy of Marie Dacke et al.

They may spend their lives rolling around on balls of poop, but dung beetles have their eyes on the stars. A new study shows that these simple bugs actually depend on the Milky Way to find their way around.

Christopher Columbus traveled by following the stars, as did Harriet Tubman. There are even birds and seals that use celestial navigation, but in the insect world, this finding is a first. In fact, the dung beetle is the first animal known to navigate via the subtle glow of the galaxy as a whole, rather than by individual stars. This may be because its compound eyes give the dung beetle a wide-angle view but poor image resolution.

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CATEGORIZED UNDER: Living World, Top Posts

Dinosaurs and Ancient Birds Shared Sex Traits

By Breanna Draxler | January 22, 2013 10:05 am

Reconstruction of Confuciusornis sanctus by Stephanie Abramowicz, NHM Dinosaur Institute.

Sue is something of a celebrity among dinosaurs, being the best-preserved T. rex fossil ever found. But in truth, the gender of dinosaurs is rarely, if ever, known. A study in 2005 first laid claim to a new way to sex dinosaurs using a distinctive bone formation. Now paleontologists in China have found that ancient birds also had this structure, confirming that birds and dinos shared similar gender divisions and reproductive habits.

Researchers excavated the 125-million-year old birds’ feathers, organs and bones from petrified lake-bottom mud in northeastern China. These birds, called Confuciusornis sanctus, were buried by the hundreds following catastrophic volcanic eruptions in the Mesozoic era.

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CATEGORIZED UNDER: Environment, Living World, Top Posts
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