Great White Sharks May Have Led to Megalodons' Extinction

iStock.com/cdascher
iStock.com/cdascher

The megalodon has been extinct for millions of years, but the huge prehistoric shark still fascinates people today. Reaching 50 feet long, it's thought to be the largest shark to ever stalk the ocean, but according to a new study, the predator may have been brought down by familiar creature: the great white shark.

As Smithsonian reports, the analysis, published in the journal PeerJ, finds that the megalodon may have vanished from seas much earlier that previously believed. Past research showed that the last megalodons died roughly 2.6 million years ago, a time when other marine life was dying off in large numbers, possibly due to a supernova blasting Earth with radiation at the end of the Pliocene epoch.

A team of paleontologists and geologists revisited the fossils that this conclusion was originally based on for their new study. They found that many of the megalodon remains had been mislabeled, marked with imprecise dates, or dated using old techniques. After reassessing the specimens, they concluded that the species had likely gone extinct at least 1 million years earlier than past research indicates.

If the megalodon vanished 3.6 million years ago rather than 2.6 million years ago, it wasn't the victim of supernova radiation. One known factor that could explain the loss of the 13 million-year-old apex predator at this time is the rise of a new competitor: the great white shark. This predator came on the scene around the same time as the megalodon's decline, and though a full-grown great white shark is less than half the size of a mature megalodon, the species still would have been a stressor. Adult great whites likely competed with juvenile megalodons, and with the megalodon's favorite prey—small whales—becoming scarce at this time, this may have been enough to wipe the megalodons from existence.

Even if great white sharks eventually beat megalodons for dominance in the oceans, the megalodon's status as one of the most fearsome predators of all time shouldn't be contested. The giant sharks had 7-inch teeth and a bite stronger than that of a T. rex.

[h/t Smithsonian]

Shocker: This Electric Eel Delivers More Voltage Than Any Creature on Earth

stacey_newman/iStock via Getty Images
stacey_newman/iStock via Getty Images

Eels are proving to be more slippery than previously believed. A newly identified species of these skinny fish (yes, eels are really fish) delivers more electric voltage than any other creature on the planet.

All species in their taxonomic order (Gymnotiformes) are capable of producing a modest electrical field to help them navigate, a perk that compensates for their poor vision. But electric eels (in the genus Electrophorus) pack a far more potent punch. They bear three organs full of cells that can produce electricity on demand. The cells act as a defense mechanism and can effectively taser prey into submission.

In a study published in Nature Communications, researchers collected more than 100 electric eels in the Amazon region and analyzed their DNA, voltage, and habitat. To their surprise, they found that the single known species of electric eel, Electrophorus electricus, was actually three distinct species. They gave the two new ones the very heavy metal names of E. varii and E. voltai. The latter (named for Alessandro Volta, who invented the electric battery) produced the strongest shock: 860 volts, topping the previous record of 650 volts.

Why the varying strength? The researchers suggested that some eels occupy water with low salt content, and therefore reduced conductivity. A stronger charge may be needed to deliver an effective jolt.

While those numbers sound formidable, their low current means a shock wouldn’t necessarily be harmful to a human. Voltage is the measure of pressure of the flow of electrons; current, or amperage, is the volume of electrons. Eels have high voltage but low current; household power outlets have lower voltage but more current and can be deadly. Eels might startle you with a shock, but it won't be fatal.

If you should find yourself in a school of electric eels bent on subduing you, however, the shocks could result in brief incapacitation that could lead to drowning or an aggravation of an existing heart condition. The study authors hope to eventually film a coordinated eel attack on (non-human) prey.

The discovery of two new species was “quite literally shocking,” lead author Carlos David de Santana told The New York Times.

[h/t Phys.org]

Does the Full Moon Really Make People Act Crazy?

iStock.com/voraorn
iStock.com/voraorn

Along with Mercury in retrograde, the full moon is a pretty popular scapegoat for bad luck and bizarre behavior. Encounter someone acting strangely? Blame it on the lunar phases! It's said that crime rates increase and emergency rooms are much busier during the full moon (though a 2004 study debunked this claim). Plus, there's that whole werewolf thing. Why would this be? The reasoning is that the moon, which affects the ocean's tides, probably exerts a similar effect on us, because the human body is made mostly of water.

This belief that the moon influences behavior is so widely held—reportedly, even 80 percent of nurses and 64 percent of doctors think it's true, according to a 1987 paper published in the Journal of Emergency Medicine [PDF]—that in 2012 a team of researchers at Université Laval's School of Psychology in Canada decided to find out if mental illness and the phases of the moon are linked [PDF].

To test the theory, the researchers evaluated 771 patients who visited emergency rooms at two hospitals in Montreal between March 2005 and April 2008. The patients chosen complained of chest pains, which doctors could not determine a medical cause for the pains. Many of the patients suffered from panic attacks, anxiety and mood disorders, or suicidal thoughts.

When the researchers compared the time of the visits to the phases of the moon, they found that there was no link between the incidence of psychological problems and the four lunar phases, with one exception: in the last lunar quarter, anxiety disorders were 32 percent less frequent. "This may be coincidental or due to factors we did not take into account," Dr. Geneviève Belleville, who directed the team of researchers, said. "But one thing is certain: we observed no full-moon or new-moon effect on psychological problems."

So rest easy (or maybe not): If people seem to act crazy during the full moon, their behavior is likely pretty similar during the rest of the lunar cycle as well.

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