American Scientist

This roundup summarizes some notable recent items about scientific research, selected from news reports compiled in Sigma Xi’s free electronic newsletters.

Animals sans Oxygen

The salty depths of the Mediterranean Sea are home to the first known anaerobic animals. Measuring just a hundredth of an inch long, three new members of the phylum Loricifera spend their lives in oxygen-starved sea sediments. To convince themselves that these surprising creatures were really alive, biologists confirmed that in the lab, the loriciferans absorbed dyes and incorporated radiolabeled amino acids into their cone-shaped bodies. Electron microscopy revealed that the new species lacked mitochondria, but were replete with hydrogenosomes—metabolic organelles previously known only from anaerobic single-celled organisms.

Danovaro, R., et al. The first metazoa living in permanently anoxic conditions. BMC Biology 8:30 (April 6)

Kudzu Smog

Add air pollution to the list of kudzu’s evildoings. The invasive vine (Pueraria montana) has taken over millions of acres in the eastern and southern United States. Symbiotic bacteria in the plant’s roots incorporate atmospheric nitrogen into the soil, where other microbes metabolize it to nitric oxide—an ozone precursor. Researchers found that, in the summer, soil in three kudzu-infested plots released twice as much nitric oxide as three kudzu-free plots. Based on atmospheric models and a worst-case kudzu invasion, the authors figure that the vine could boost ozone levels above air-quality limits for seven extra days per summer.

Hickman, J. E., et al. Kudzu (Pueraria montana) invasion doubles emissions of nitric oxide and increases ozone pollution. Proceedings of the National Academy of Sciences (published online May 17)

Ball Lightning Solved?

Despite thousands of eyewitness reports, the nature—and even the existence—of ball lightning remains uncertain. Now a pair of physicists claims that the orbs of light might be storm-induced hallucinations. A clinical technique known as transcranial magnetic stimulation focuses a magnetic field on parts of peoples’ brains and can cause them to perceive glowing bubbles of light. Calculations reveal that a lightning strike pulsing back and forth between cloud and ground could generate a comparable field, causing hallucinations of ball lightning among observers up to a tenth of a mile away. The authors speculate that such illusions could account for up to half of ball-lightning sightings.

Peer, J., and A. Kendl. Transcranial stimulability of phosphenes by long lightning electromagnetic pulses. Physics Letters A (published online May 12)

Fountains in Palenque

Ancient Mayans enjoyed pressurized water in the city of Palenque a good millennium before the Spanish arrived. The city’s residents regularly routed streams through underground channels to make space for buildings. Archaeologists recently noticed that one of these aqueducts suddenly narrowed before emerging from the ground. Forcing the water through a small space would have pressurized it, and could have powered a fountain up to 15 feet high. Archaeologists aren’t sure how the Mayans used the pressurized water, but it may have washed away waste or filled water vessels. The find is the only known example of engineered water pressure in the pre-Hispanic Americas.

French, K. D., and C. J. Duffy. Prehispanic water pressure: A New World first. Journal of Archaeological Science 37:1027–1032 (May)

Queasy Quolls

A dinner of invasive cane toad (Bufo marinus) doesn’t taste bad to Australia’s native predators, but it’s deadly. The toxic amphibians have driven the northern quoll (Dasyurus hallucatus), a cat-sized carnivore, to the verge of extinction. Even after surviving an unpleasant toad encounter, most quolls are willing to try it again. Determined to help, conservation biologists educated 31 of the predators by feeding them small non-lethal cane toads spiked with a nauseating chemical. Indeed, captive quolls that suffered upset stomach were four times less likely than naive quolls to attack another toad. They also survived longer when released into toad-infested habitats.

O’Donnell, S., et al. Conditioned taste aversion enhances the survival of an endangered predator imperilled by a toxic invader. Journal of Applied Ecology 47:558–565 (June)

Who’s the Better Mushroom Hunter?

Men may take pride in their spatial aptitude, but women have unique navigation skills of their own. Evolution probably honed men’s route finding during the Pleistocene, when hunters followed their quarry into unknown terrain. Women would have gathered immobile plant foods—a role that might favor different navigational tactics. To test this idea, biologists outfitted themselves with GPS devices and heart-rate monitors and followed 21 men and 21 women mushroom hunting in central Mexico. Men chose longer and more strenuous routes, but in the end, they collected no more fungi. Women indeed may be optimized to efficiently gather food that doesn’t run away.

Pacheco-Cobosa, L., et al. Sex differences in mushroom gathering: Men expend more energy to obtain equivalent benefits. Evolution and Human Behavior (published online April 23)

A Speedy Cold Current

An ocean current that shuttles near-freezing water from Antarctica toward Australia is now the fastest deepocean current on record. It flows at eight times the rate of all Earth’s rivers combined. Researchers knew that a frigid stream moved through that part of the ocean, but there were no reliable measurements of how much water it carried. Using remotely operated submarines, researchers moored more than 50 current and temperature sensors across 100 miles of seafloor. The data reveal a remarkably intense and consistent current, moving at a half-mile per hour along a path only 30 miles wide. The newly measured flow will be an important element in future climate models.

Fukamachi, Y., et al. Strong export of Antarctic Bottom Water east of the Kerguelen plateau. Nature Geoscience (published online April 25)