by Becky Crew
Unexpectedly, the researchers, reporting in PLoS Biology, found that the Substance P–infused naked mole rats still showed no reaction when acid was applied to their skin. “The mole rat is the only animal that shows completely no response to acid,” says coauthor Thomas Park from the University of Illinois.
Late last year, the German researchers investigated the naked mole rat’s apparent insensitivity to acid. In most mammals’ body tissues, carbon dioxide is converted into acid, which, when it builds up, continuously activates the body’s pain sensors. Because this rodent lives in an environment where carbon dioxide levels are incredibly high, the research suggested that through evolution they have ended up with altered sodium ion channels in their pain receptors that are inactivated by any kind of acid. There are rare cases of humans born without these types of ion channels, called Nav1.7, who cannot feel pain, and there’s a type of local anesthetic that dentists use that has sodium ion channel blockers to induce this same insensitivity to pain.
Around the same time, researchers from the University of Liverpool’s Institute of Integrative Biology in England sequenced the complete genome of the naked mole rat to figure out how it can live for up to three decades in harsh underground conditions—while avoiding cancer the entire time—while other rodents such as mice can only manage a lifespan of four years. Working with scientists from Harvard University, the team discovered that particular genes of the naked mole rat that are associated with mitochondria—tiny organelles that provide the energy a cell requires to move and divide—and respiratory and cell decision-making systems are expressed in abnormally high levels when compared to the same genes in regular wild mice. The researchers, publishing in PLoS ONE in late 2011, suggested that high levels of genes associated with energy production and cell decision-making processes may be the key to the animal’s anti-aging, anti-cancer intracellular environment.
For all their truly bizarre qualities, some scientists are pushing for the naked mole rat to become more widely used in scientific research, replacing the grossly overused and farmed common mouse. If they can teach us how they have managed to completely avoid contracting cancer, even when tumors are deliberately implanted inside their bodies to see if they will grow, that would really be something.
Flying Buttocks
PIGBUTT WORM
(Chaetopterus pugaporcinus)
ALMOST 3280 FEET BELOW the ocean surface, the pigbutt worm doesn’t do much besides float around looking like the rear end of a pig. Named Chaetopterus pugaporcinus—which literally means “worm that looks like a pig’s rump”—the pigbutt worm was discovered in 2006 by Monterey Bay Aquarium Research Institute’s Karen Osborn (of swima worm fame). It was scooped up by a remotely operated vehicle (ROV) patrolling the mesopelagic zone just off Monterey Bay in California, which occupies the ocean from 656 feet below the surface to around 3280 feet. While a little sunlight penetrates it through the epipelagic zone directly above, many animals in the mesopelagic rely on bioluminescence for signaling and communication.
You only have to look at this otherworldly blue balloon with its pink, puckered mouth to know that this is unlike any other worm in the world. Osborn found that although it has a segmented body, one of the middle segments is flat, causing the two outer segments to inflate like a balloon to give it the appearance of a rear end. Because it shares some similarities with the larvae of a group of marine filter feeding polychaete (or segmented) worms called the Chaetopteridae, Osborn thought the pigbutt worm might be in its larval stage. However, it being the relatively formidable size (for a marine worm) of a hazelnut, Osborn conceded in a 2007 issue of the Biological Bulletin, “If the specimens described here are larvae, they are remarkable for their size, which … is five to ten times larger than any known chaetopterid larvae.”
The only other option was that this worm was in its adult form, making it the strangest-looking adult chaetopterid anyone had ever seen. All known adult chaetopterid worms have long, segmented bodies, and live inside vertical or horseshoe-shaped tubes inside tunnels buried in the seafloor. Here they spend their days catching plankton with the mucus net they make and suspend over the top of the tube. But the pigbutt worm drifts at a depth of 2950–3935 feet, its downward-turned mouth surrounded by a cloud of mucus, which Osborn thinks might be used to capture tiny food particles and detritus that float down from the higher water levels. The pigbutt worms also lack reproductive organs, which makes them even more inscrutable, but Osborn says that this means the specimens that were caught were not immediately in the process of reproducing, not that they don’t do so. “Many annelid [segmented] worms only have evidence of reproductive organs when actively reproducing, which can be for just a few weeks to a couple months,” she added.
Unable to classify this worm based on morphological features, Osborn and her team analyzed the DNA from dozens of marine worms, creating the first family tree to represent the relationships between twelve species of chaetopterid worms. This didn’t help them discover whether this new species is in its larval or adult form, but the team suggested that its strange appearance may be the result of the larvae finding themselves unable to settle on the seafloor like the other worms, which hindered the growth process, restricting them to the larval form forever. “They may be larvae that missed their cue to settle out to the seafloor or never found suitable habitat, but that seems unlikely considering the consistency with which we find them in a specific midwater habitat and the consistency of their morphology no matter what size they are (ranging from 0.5–1 inch),” says Osborn. “They always have the same number of segments and the same mix of larval and adult characters. It would be nice to find one in the process of reproducing so we would know if they can complete their life cycle wholly within the water column.”
Yeah, so the pigbutt worm might look like the rear end of a disgusting mammal, but that doesn’t seem to bother him. Cruising around, not giving a shit about what the other chaetopterid worms are doing is what made him a pigbutt worm in the first place, so I bet they’re generally pretty chill. Like, it’d be the first day of high school and Pigbutt Worm will be transferring from another school and all the cool kids will be like, “OMG. Have you seen the new guy? He looks like ass,” while they hang out in their tubes on the seafloor.
And Pigbutt Worm will float past, pretty much oblivious but also not really caring, being all, “Hey man, what’s up?”
And most of the cool kids will continue to make fun of him, blaming their farts on him and making him do chemistry pracs on his own, but Pigbutt Worm will take it all in his stride, and after school will hang out with the more mature college kids who don’t give a shit about things just as hard as he doesn’t give a shit about things. Of course, this will invariably lead to one of the cool females hatching a scheme with one of the cool males to set Pigbutt Worm up with the cool female’s older sister so her overbearing dad will let them both go to the school dance, and that’s good for the cool male because he’ll get to bang the cool female after the dance for the first time. And Pigbutt Worm will go along with it because he doesn’t really give a shit and was probably high the whole time anyway.
But as things progress, Pigbutt Worm will develop an actual crush on the sister because she almost doesn’t give a shit harder than he doesn’t give a shit, and she’ll start to like him back because she hates most people except for him. Of course, the scheme will be revealed at the dance, when everyone is dressed up in their suits and evening gowns made of seaweed, and the sister will think Pigbutt Worm doesn’t give a shit about anything, especially her, even though he does.
And then a huge fish will crash through the upturned shell that is the dance hall and swallow everyone in a single gulp. Guess that overbearing dad was right after all.
The Elusive Stick Giant
LORD HOWE ISLAND STICK INSECT
(Dryococelus australis)
“Jehovah’s Witnesses? Seriously? How the fuck did you guys find me out here?”
FOR AN INSECT TO be ot
herwise known as a “land lobster,” you know it’s got to be seriously big. The Lord Howe Island stick insect is a flightless, nocturnal insect that stretches up to 5 inches long, its solid, rust-colored body weighing around 0.28–0.32 ounces. When you consider the average cockroach doesn’t grow beyond one tenth of an ounce, you can get a pretty good idea of how large these things are. But the enormous size of the Lord Howe Island stick insect, which gives them an air of something prehistoric, is not the strangest thing about them. In 2001, these hefty stick insects were brought back from the dead.
Lord Howe Island is a crescent-shaped volcanic island that sits between Australia and New Zealand about 373 miles from Port Macquarie in New South Wales, with a population of around 350 people. In the nineteenth century the Lord Howe Island stick insect prowled this Australian territory in such numbers that fishermen would use them as bait and ladies would dread finding them in their outhouse toilets. But then the rodents came. Mice were introduced to the island in the 1880s, followed by black rats in 1918 when they hitched a ride on the British vessel SS Makambo, and they made more than a meal or two out of the island’s meaty insect residents, not to mention its unique species of birds. Sightings of the Lord Howe Island stick insect dropped off dramatically shortly afterwards, until by 1920 not a single one was recorded, and by 1960 they were officially proclaimed extinct.
But in the late 1960s, sightings of stick insect remains were reported on Ball’s Pyramid, a supersheer volcanic remnant that sits 12 miles from Lord Howe Island. Said to be the tallest volcanic stack in the world, Ball’s Pyramid is about 1805 feet high, around 985 feet wide and 0.6 miles long, and it’s so narrow that there’s no way anyone’s landing a boat on it. Instead, you have to anchor your boat in the ocean surrounding it, launch yourself onto the vertical pyramid wall and climb your way up. Needless to say, this place is an explorer’s dream, and many climbing groups were desperate to seek out the fabled stick insect. But in 1984, the Lord Howe Island Board, a seven-member group sanctioned by the NSW government to handle environmental concerns regarding the territory, banned any climbing on Ball’s Pyramid except for scientific work. And even then, you would have to make a really impressive case to gain approval.
Between 1998 and 2001, Australian scientists David Priddel and Nicholas Carlile began planning their way onto Ball’s Pyramid—not to find the Lord Howe Island stick insect, but to prove, once and for all, that the species was dead and gone. The pair, who worked for the NSW Government’s Office of Environment and Heritage on issues related to the recovery of threatened species, knew they couldn’t just grab any scientist and get climbing approval, so they recruited local ranger Dean Hiscox, entomologist Stephen Fellenberg, and entomology curator Margaret Humphrey from the Macleay Museum at the University of Sydney. “David and I decided the only way to mount a trip to Ball’s Pyramid was to take some entomologists, and to prove the things weren’t there,” says Carlile.
It took four years for the team to make it out to Lord Howe Island, and even once they got there in 2001, they had wait for almost a week for just the right sea conditions before attempting to cross over and land on Ball’s Pyramid. There’s no way you’d attempt to launch yourself onto the sheer wall of Ball’s Pyramid from a tiny boat in choppy waters. The researchers also knew that the Lord Howe Island stick insect was nocturnal, so rather than attempting to look for the animals themselves, which meant climbing the formation at night, they decided to look for droppings or any other indications of the insect during the day. “We knew from stories passed down from the locals, and the one scientific paper [published in 1969 by Australian entomologist Arthur Mills Lea], that they are nocturnal, and lived inside logs and hollows in trees because they couldn’t cope with drying out in the Sun,” says Carlile.
Having established a base camp on a high wave-cut platform, they climbed about 490 feet up the side of Ball’s Pyramid to Gannet Green, with the largest invertebrate find being remains of a couple of large crickets. The harsh conditions forced them back to their base before day’s end, so before getting dizzy and dehydrated, they edged their way back down to the boat. On their way down, the researchers noticed a group of Melaleuca howeana bushes growing from within a small crevice that seeped water, supported by a peaty buildup of soil—possibly the only place like it containing what could be the only patch of soil on the whole of Ball’s Pyramid. M. howeana is a dense, short bush endemic to Lord Howe Island, and is hardy enough to thrive in exposed, rocky sites. Underneath this one bush was, as Carlile described it, “several large insect frass (poos).”
The researchers thought it was likely that the sizeable poo belonged to one of the large crickets they had seen earlier that day, but the only way to prove it was from the Lord Howe Island stick insect was to return to the Melaleuca bush that night. “We had an instamatic camera (it was predigital days) with three shots left, and a head torch each. I hadn’t had my kids at that stage so I was still up for a bit of derring-do,” says Carlile. “We found the shrub and there were two bloody huge insects straddling it.” At that point, the researchers became the only people alive to have ever seen a living Lord Howe Island stick insect. “It was just phenomenal. Even twelve, thirteen years later it is one of the highlights of my life. We’d been talking about and planning this trip for years because we wanted to show that it wasn’t there, so this total 180 was surprising to say the least,” says Carlile.
Looking inside the Melaleuca, they found a juvenile stick insect. Incredibly, it turned out that this one bush sustained the entire Ball’s Pyramid population of Lord Howe Island stick insects—between twenty-four and forty individuals—which meant it sustained the entire species. Stick insects are generally pretty flexible when it comes to eating different types of plants, so long as they are introduced to it as juveniles, but what they can’t live without is soil because their eggs won’t hatch on dry, spare rock. “This single shrub is significant to the entire species of the invertebrate. That’s why it is so rare,” says Carlile. For this reason the Lord Howe Island stick insect gained the reputation of being the rarest insect on Earth. Just how they made it from Lord Howe Island to the safety of the rodentless Ball’s Pyramid, when they couldn’t fly, is something no one has been able to answer conclusively, but Carlile thinks they were either tossed onto the rocks as discarded fish bait, or were mistakenly collected as nesting material by a type of seabird called the Common Noddy.
In 2003, the researchers were given approval to collect two breeding pairs of Lord Howe Island stick insects. They gave one to Fellenberg to breed in Sydney and one to the Melbourne Zoo. Fellenberg’s female died, as they can be a tricky species to keep in captivity, but from the Melbourne Zoo pair, 21 eggs were produced from which healthy young hatched. According to Carlile, the Zoo now has about 1000 adults and 20,000 eggs. The plan now is to go back to Ball’s Pyramid and collect more eggs to improve the genetic robustness of the captive population, but, as with the researchers’ first trip out there in 2001, this requires a lot of planning, and waiting for the perfect conditions. “The window just hasn’t been there,” says Carlile. The long-term plan for these rediscovered insects is for the rats and mice to be completely eradicated from Lord Howe Island as early as 2015—a $10 million project, according to Carlile—and the captive population reintroduced with a species of owl to keep them in check. “We can’t reintroduce them now,” says Carlile, “But that is our aim.”
At Home in Someone Else’s Anus
PEARLFISH
(Carapidae)
THIS SLENDER, TRANSLUCENT, AND scaleless fish really takes advantage of being pencil thin. Not content to make its own home in the seabed or the crevices of rocks, almost all species of the pearlfish family live in the body cavities of invertebrates such as clams, oysters, and starfish. And a notorious few reside exclusively in the anuses of sea cucumbers.
“Pearlfish” is the common name of the Carapidae family, which includes thirty-one species of fish that live in the tropical waters of every ocean on Ea
rth except the Arctic, and can be found in both shallow waters and at a depth of up to 1.2 miles below the surface. The family earned its common name after a dead pearlfish was discovered inside an oyster shell; it had been encrusted and paralyzed by the substance produced by an oyster to create its shell’s second inner layer—the mother-of-pearl lining.
Not all pearlfish find the experience of residing inside other sea creatures so perilous. On the contrary, this behavior ensures a safe haven for the delicate fish, keeping them hidden from predators during the day, before a spot of nocturnal foraging, according to some researchers. Some species find sea cucumbers (Holothuriidae) to be particularly accommodating hosts, as they are found in great numbers in the world’s oceans, often forming very dense populations in shallower waters, plus they move sluggishly and are extremely nonaggressive scavengers. So genial are sea cucumbers that of all the echinoderms—a large group of “spiny-skinned” marine animals including starfish and sea urchins—they are the most heavily parasitized, playing host to a menagerie of smaller creatures such as crabs, worms, and bacteria.
