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Piranha kin had nasty bite

Pound-for-pound, an ancient relative of today’s piranhas had a stronger bite than gators, sharks and even the mighty Tyrannosaurus rex. That’s the conclusion of field studies carried out on the black piranha (Serrasalmus rhombeus), the largest living species in the carnivorous clan. The largest of the 15 fish tested, a 2.4-pound specimen measuring about 14.5 inches long, clamped down on researchers’ test equipment with a force almost 30 times its own weight – a ratio unmatched among vertebrates, researchers revealed online Dec. 20 in Scientific Reports.

Extrapolating 10 million years back, the team estimates that the jaw-tip bite force of the black piranha’s extinct relative – Megapiranha paranensis, which might have reached lengths of about 1.3 meters and weighed up to 160 pounds – could have been as high as 1,067 pounds. Previous studies have calculated the bite force of T. rex to be almost three times that of Megapiranha, but it’s important to note, the researchers say, that T. rex was more than 100 times heftier. Not only were Megapiranha’s teeth fringed with tiny serrations, unlike the teeth of their modern-day kin, but they also had stout circular roots - a combination that rendered them sharp enough to slice flesh yet sturdy enough to crush the shells of turtles and pierce the armor plates of catfish that lived in the same ecosystem.

Sprites emit radio waves

Red sprites, the enigmatic electrical discharges that sometimes occur high over thunderstorms in the wake of strong lightning strikes in the lower atmosphere, can emit low-frequency radio waves, a new analysis suggests. Analyses of how highly charged molecules generated by sprites would behave suggest that individual, kilometers-long streamers within sprites - somewhat analogous to single bolts of lightning - could indeed act as antennas, generating radio waves at many different frequencies. At an altitude of 75 kilometers, streamers would emit radio waves at frequencies below 3 kilohertz, or 3000 cycles per second, the researchers reported in November in Geophysical Research Letters.

ScienceNOW, the daily online news service of the journal Science.