This Prehistoric Elephant Had a Huge Spork for a Mouth

The Half-Ton Giant Freshwater Stingray With a 15-Inch Poison Barb

Sailor lore once told of a whale so enormous that captains would mistake it for an island, anchoring their ships to the beast and ordering men ashore. When the sailors built a fire on this "island whale," though, the fiend would heave up and dive, dragging the crew to their deaths and perhaps into starring roles in the Pirates of the Caribbean movies. And on the way down they likely thought, I knew I saw an eyeball back there. I should have said something. But also, Well isn't this just a doozy. Something so big, yet we didn't realize it was right under our feet.

Scientists were probably thinking the same thing when in 1990 they first described Southeast Asia's giant freshwater stingray, which can grow to more than 16 feet long and 1,300 pounds. And while it packs a 15-inch, poisonous, serrated stinger, it's actually a gentle, inquisitive creature, an endangered titan that researchers are scrambling to understand before humans drive it to extinction.

Though this could be the largest freshwater fish on the planet, accounts of its existence only emerged in Thai newspapers in the early 1980s. It's exceedingly rare to see one, in part because it destroys all but the strongest fishing rods and lines. Even if you have the right equipment, the giant freshwater stingray tends to take exception to being hunted and buries itself in the river bottom when hooked. In 2010, 15 anglers working in shifts reportedly spent six hours reeling one in, which either says something about the stingray's strength or the group's collective fishing skills. The fish can drag boats for miles, and even pull them under.

And while its toxic spike has been said to pierce the hulls of fishing boats — not to mention bone — it uses this fearsome weapon only as a last resort to defend itself. "They're inquisitive, they're not as shy as most other species of fish," said Zeb Hogan, a conservation biologist with the University of Nevada, Reno. "There aren't many fish out there that like to be approached, that will stay in one place if they're close to humans, and the stingrays don't seem to mind being in close proximity to humans. They don't in some cases seem to even mind contact."

This isn't to say you should for a moment stop respecting the stingray's awesome barb. Once it goes in, it won't easily come out, on account of its backward-facing spines. Even the smallest cut can result in agony, kinda like cat scratch fever but with 100 percent less Ted Nugent.

"It's a spine covered by a kind of very thin membrane, and trapped in that membrane is a toxin that causes pain, for one thing, but can also cause infection," said Hogan. "I've never been stung directly, but I've rubbed up against the spine and had my skin receive a small cut, and it's just an immediate painful stinging sensation."

"I can't imagine what it'd be like to actually be really jabbed by one," he added. "It swells, it's painful, the wounds almost always get infected, and the best way to relieve some of the pain and swelling is to actually pour hot water over the wound as soon as possible. Apparently that breaks down some of the toxin."

In the Mekong River, which nurtures more super-massive fish than anywhere else in the world (.pdf), this stingray is a giant among lesser giants. Consider the positively puny giant Mekong catfish and giant barb, both of which are a measly 10 feet long and 650 pounds. They've probably been focusing too much on cardio and too little on weight training. Classic mistake.

This ecosystem supports an abundance of fish and invertebrates like crabs and shrimp for the giant freshwater stingray to prey upon, which it finds with electroreception, like sharks do. It hunts by first settling over and essentially smothering its prey, then directing the quarry into its mouth, where it is crushed by powerful plates. (Hogan said he once offered a shrimp to one of these stingrays in captivity — by letting the animal cover him like a wiggly blanket. He called this an "interesting sensation.")

The Mekong's incredible biodiversity and plentiful space for large creatures to roam — combined with the tendency for fish to grow quicker in warmer waters — allow the stingray to attain its staggering size, according to Hogan. But the giant freshwater stingray and other Mekong giants are in serious trouble. Indeed, Hogan believes that these large fish are the litmus test for the health of the whole ecosystem, and at the moment, things aren't looking good.

Habitat degradation from pollution and damming have driven the giant Mekong catfish, the giant barb, and the giant freshwater stingray nearly to extinction. Making things worse, sportfishermen catch the endangered monsters for the thrill of it — even when released, the massive stingrays and catfish can be stressed to death. And then there are the aquariums vying to acquire the fish for their collections.

But according to Hogan, the stingray's size is at once a curse and a boon. "Most fishermen in Southeast Asia, if they have a fish that's large enough to use as a bait for a stingray, that's already something that they want to keep just for themselves," he said. "And they would also have to invest in very strong line and very strong hooks, and so stingrays are actually doing better [than other large fish] because at least in the part of the world where they occur they're pretty hard to catch using the gear that people are using there. That's a little bit of good news."

So while the Mekong's condition degrades as it sprouts ever more dams, and locals find themselves reeling in ever fewer fish — titans or otherwise — perhaps the giant freshwater stingray can yet avoid joining the rascally island whale in fisherman lore.

Aye-Aye Gives World the Highly Elongated Finger

The Zombie Ant and the Fungus That Controls Its Mind

The zombie is a simple creature with simple tastes, enjoying leisurely walks on the beach, dining out with hordes of its friends, and every now and then having a good tumble down a flight of stairs. It behaves this way because the pathogen that has infected it doesn't require complex behaviors in order to replicate — it commands a hungry, nearly indestructible vessel that can walk it right up to its next potential host.

But on our planet there exist zombified ants that undergo a decidedly more complex, and more disturbing, transformation at the hands of highly sophisticated parasitic fungi that assume control of the insects' minds. What ensues between a host and a parasite with no brain of its own is a battle that is far stranger and far more methodical than anything ever dreamed up by Hollywood. (The zombifying fungus that attacks humans in the videogame The Last of Us comes close, but its real-life counterpart is much, much weirder. And you don't have to pay 60 bucks to see it, which is nice.)

For many of us it's hard to feel for ants, what with them ruining picnics or even entire cities, but it's downright disquieting to watch one infected by these parasitic fungi — species in the genus Ophiocordyceps that each, incredibly, attack only a single species of ant. Once a disciplined member of a rigidly structured society, the affected ant stumbles out of its colony like the town drunkard, guided by a pathogen that has pickled its brain with a cocktail of chemicals.

Once a disciplined member of a rigidly structured society, the affected ant stumbles out of its colony like the town drunkard, guided by a pathogen that has pickled its brain with a cocktail of chemicals.

The ant heads, at the behest of the fungus, to a precise position in the forest. Scientists plotting the coordinates of these unfortunate ants have documented a striking regularity to their travels, making the pathogen a bit like GPS for the insect, only, you know, the ant never asked for directions.

The ants "are manipulated to bite onto very specific locations on the underside of a leaf, the main vein of a leaf, leaves orientated north, northwest, roughly 25 cm off the ground," said David Hughes, a behavioral ecologist at Penn State. "And all of this happens with a remarkable precision around solar noon, making this one of the most complex examples of parasite manipulation of host behavior."

It's a position chosen by the fungus, rather unbelievably, for its ideal temperature and humidity — Hughes has experimented with this by moving the ants out of these spots to drier, hotter areas, where the fungus failed to grow. Once the ant has anchored itself by sinking its mandibles into the leaf's vein, it perishes, and from the back of its head erupts a stalk, which, while in a way is quite beautiful, might be considered the world's least desirable hat. This in turn rains spores down onto the ant's fellow workers below, attaching to their exoskeletons and beginning what could euphemistically be called an invasive procedure.

"In order to get through [the exoskeleton], the fungus builds up a pressure," said Hughes. "We know from studies of fungal parasites of plants, particularly rice, they can build up a pressure inside their spore equivalent to the pressure in the wheel of a 747. So they have a massive buildup of pressure, and when that's at a sufficient level then they blow a hole through the wall and blow all the genetic material" into the ant.

Thus the cycle begins anew.

According to Hughes, in addition to the 160 known species of ant-controlling fungi, there may be some 1,000 additional varieties out there to be discovered. These don't even account for the array of additional parasitic fungi that exclusively target specific species of other insects, from beetles to butterflies (let's face it, butterflies could use to get taken down a notch or two).

The relationship is a remarkable illustration of host-parasite coevolution that scientists are just beginning to understand — fossil records of bite-scarred leaves show this has been happening (.pdf) for at least 48 million years — with ant-hunters, each dependent on a single species, developing astounding adaptations to survive. And in response, the ants have evolved their own brilliant defenses, far beyond anything you learned from SimAnt.

"The fungus needs to transmit," said Hughes, "and it cannot do that inside the nest, because in order for ant societies to work, they have necessarily evolved a prophylactic immune system, which is reliant upon behavioral defense. So they have something called social immunity. They simply stop diseases spreading inside their nest by finding diseased individuals and moving them out."

Despite the ants' countermeasures, these fungi are extremely virulent and can, as if trying to show off, wipe out whole colonies. Left unchecked, the fungi might conceivably drive themselves and their ant hosts to extinction. But this is where the tale gets stranger. The parasitic fungi themselves have their own parasitic fungi.

The very success that allows the fungi to build up what Hughes calls "graveyards in the forest" also "invites other organisms to come in and infect them," he said. "And these hyperparasitic fungi castrate the zombie ant fungi. So the zombie ant fungi rely upon a spore body that releases spores and continues to cycle, and the other parasite comes in and whacks it out." In one study Hughes found that only 6.5 percent of a zombie ant fungi's fruiting bodies produced viable spores.

The whole weird circus is still somewhat mysterious, but Hughes is studying infected ants in the lab to figure out what kinds of chemicals the fungi are using to achieve mind-control, and how exactly mind-control affects transmission. These species, after all, are not alone among fungi in their psychoactive tendencies. LSD was synthesized from ergot, a rye-loving fungus theorized, though far from proven, to have tripped out the poor souls accused in the Salem Witch Trials, which it turns out wasn't nearly as groovy of a situation as it sounds, on account of all the capital punishment.

"We're discovering that over half of life on Earth is parasitic," Hughes said. "It's the most common mode of existence in the history of life on Earth. But only a tiny minority of parasites do mind-control. And why is that? What is the push in order to control the behavior of your host?"

Other than to enjoy a leisurely stroll on the beach, of course.

Further reading: Those interested in academic explorations of zombie fungi and other pathogens can sign up for Penn State's free online course Epidemics: The Dynamics of Infectious Diseases, which begins Oct. 15.

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