by Becky Crew
What remains to be discovered is whether or not the bone-claws of the hairy frog are retractable. Do the frogs get one shot at pushing their bones through their skin in an emergency, or can they somehow fit them back inside the tips of their toes while their skin grows back over the top? And does puncturing their own flesh like this hurt? “We need to do some basic experiments with living animals to figure this out,” says Blackburn.
Bomb-Dropping Worm
SWIMA WORM
(Swima bombiviridis)
“I’d like to check in please. Flying to New York.”
“Sure thing, sir, I just need your passpor—Wait, is this some kind of joke? Are those things real?”
“Look, I am begging you, this is the seventeenth airline I’ve tried, and every time I come to catch my flight I leave these things at home, but they grow back so fast, I can’t control it. I just want to see my niece get christened, that’s all I want to do.”
“Security!”
“Okay, okay, don’t bother. Look, I’m throwing myself out. But these tickets had better be refund—Okay, okay, I’m going!”
WITH JUST 9 PERCENT of the ocean’s species discovered so far, we have no idea how weird things really get down there. But every new species gives us a hint that life on the land is nowhere near as bizarre.
In 2009, a handful of new deep-sea worm species was discovered off the west coast of the United States thanks to a remotely operated submersible vehicle that was patrolling the ocean between 1 and 2.3 miles below the surface. The research team behind the discovery, led by marine biologist Karen Osborn from the Scripps Institution of Oceanography at the University of California in San Diego, identified seven previously unknown species, including a swima, or bomb-dropping, worm called Swima bombiviridis, which sports eight “bomblike” appendages attached to the segments behind its head. “We found a whole new group of fairly large, extraordinary animals that we never knew anything about before,” says Osborn. “These are not rare animals. Often when we see them they number in the hundreds. What’s unique is that their habitat is really hard to sample.”
Transparent, eyeless swima worms range in size from 0.7 to 3.7 inches, and their gelatinous bodies are transparent except for a bright orange gut area and the light green bombs. When agitated or threatened, the bombs—or pinhead-sized sacs filled with bioluminescent liquid—are released, and burst into a bright green light that glows for several seconds as they float away. One or two bombs are released at a time and are automatically replaced by the swima worm’s body. According to Osborn, who published a description of the worms in Science two years following the discovery, the bombs are likely to be a defense mechanism rather than a courting device as they are used by both juvenile and adult worms alike. Because light is so limited in the deep sea where they live, the glowing bombs could function as a predator distraction while the worm escapes into the darkness.
Judging by the position of the bombs and the fact that they are so easily detachable, the researchers think they may have evolved from gills, as their ancestors’ gills are positioned in exactly the same place. “The gills can fall off very easily so there’s a similarity of being detachable, but for some reason the gills have transformed to become these glowing little detachable spheres,” says coauthor and curator of Scripps Benthic Invertebrate Collection Greg Rouse.
The swima worms are not only well equipped for distracting predators, they’re also very skilled swimmers. They’re flanked by fans of long bristles that form swimming paddles that allow them to move both forwards and backwards, and the large surface area of the fans is perfect for propelling them through the water at a fast pace.
In late 2010, Osborn described the swima worms’ slower, less weaponized relative called the squidworm (Teuthidodrilus samae). This blue and yellow creature looks like a combination of a swima worm and a squid, with ten slender tentacles protruding from its head. Two of the tentacles are yellow and curled loosely like a corkscrew, which Osborn suggests are used for feeding. The remaining eight blue tentacles are likely used for breathing, and could also help the squidworm feel its way around in the dark. Like the swima worm, the squidworm’s body is also lined with an array of bristles, but it tends to swim at a more leisurely pace, filtering the matter that makes its way down from the surface for food.
The Toxic Songbird
HOODED PITOHUI
(Pitohui dichrous)
“Us? You want to feed us to your dog? Look, I respect the fact that you caught us—that’s pretty impressive seeing as we have wings and you don’t—but I’m telling you right now, this is a bad, terrible idea. If you want our advice—and you don’t seem to because you’re ignoring us, but regardless—feed us to some stray you picked up on the street. Someone’s gonna die either way, that’s for sure, and it just doesn’t make sense that you’d want it to be your own pet. You know?”
IN THE EARLY 1800S, French-born ornithologist, naturalist, and painter John James Audubon was traveling along the Mississippi River when he decided to put the rumors of the Carolina parakeet’s (Conuropsis carolinensis) toxicity to the test. Dash, his hunting dog, was to be the guinea pig.
Carolina parakeets were a species of small parrots, resplendent in jade green, pale yellow, and gold plumage, and they had once littered the southeastern United States. Rumored to be poison birds, they gained a reputation from the native Americans and settlers alike as having the capacity to kill a cat, as Audubon mentioned in a journal entry from December 29, 1820:
We Boiled ten Parokeets tonight for Dash who has had ten Welps—purposely to try … the Poisoning effect of their hearts on animals. Yesterday We Were told that seven Cats had been Killed Last Summer by Eating as Many Parokeets.
What happened to Dash following a meal of Carolina parakeets was never confirmed, but Audubon kept a very thorough journal, and following the previous entry, Dash was never mentioned again.
Just a few years earlier, Scottish-American poet and ornithologist Alexander Wilson decided to test the Carolina parakeet’s poison on his pet as well—a cat called Mrs. Puss. But cats will be cats, and Mrs. Puss proved a far less doting guinea pig than poor old Dash, according to Wilson writing in Wilson’s American Ornithology in 1808:
A very general opinion prevails, that the brains and intestines of the Carolina Parakeet are a sure and fatal poison to cats. I had determined, when at Big Bone, to put this to the test of experiment; and for that purpose collected the brains and bowels of more than a dozen of them. But after close search Mrs. Puss was not to be found, being engaged perhaps on more agreeable business.
Wilson convinced a friend to feed the poison birds to her cats instead, testing a mother cat and her two kittens himself, only to find all had lived after consuming every part, leaving just the beaks. Why these cats had not succumbed to the Carolina parakeet’s poison was a mystery, but Wilson put it down to the difference in diet between the wild and captive birds. “Still, however, the effect might have been different, had the daily food of the bird been cockle burrs, instead of Indian corn,” he wrote in American Ornithology: Or the Natural History of the Birds of the United States. The seeds of the cockle burr plant were a known poison to cats, so Wilson concluded that this could be the source of the Carolina parakeet’s poisonous insides.
Now extinct due to deforestation and overhunting, the Carolina parakeet was worn down to a single captive male called Incas, who died in 1918. Yet a few species of toxic birds remain today, most notably in the New Guinea bush where, in 1989, chairman and assistant curator of the Department of Ornithology and Mammalogy at the California Academy of Sciences, Jack Dumbacher, stumbled on the extraordinary secret of a striking bird called the hooded pitohui. Dumbacher recalls his first encounter with the pitohui:
It was all very accidental. I was in Papua New Guinea with a team of folks studying Raggiana birds of paradise. We had many mist nets scattered in the forest for catching the birds of paradise, but we caught many other birds as well. One day, several hooded pitoh
uis were in a net. These are large birds that can cut your hands, and as I struggled to free them, they bit and scratched my hands. These little scratches really stung, so I just put my fingers in my mouth to clean the cut, and after a minute or so my lips and tongue began to tingle and burn. After this happened to one of our volunteers, we put the stories together and wondered whether it was possible if the bird was the source of the tingling. The next time we caught a pitohui, we tasted a feather, and there was the tingling burning sensation—and the toxin. When we asked the local guides, they all seemed to know about this.
Popping a feather on his tongue, Dumbacher reported that the tingling sensation could last for hours, and gathered a bunch to take back with him to the States. Serendipitously, the chemist who agreed to identify the pitohui’s poison was John Daly from the National Institutes of Health, the man who in the 1960s discovered batrachotoxins—extremely potent neurotoxic steroidal alkaloids—in the poison dart frogs of Central and South America. Ounce for ounce, this is one of the most toxic natural substances known, and in 1992, Daly isolated this same poison in a sample from one of Dumbacher’s birds. That year the poisonous pitohui and Dumbacher’s discovery found itself on the cover of Science.
In 2004, Dumbacher reported in Proceedings of the National Academy of Sciences that a group of New Guinea villagers had identified where the pitohuis sourced their batrachotoxins. Just as the Texas horned lizard gets its poison from Pogonomyrmex ants, it appeared as if a group of small, colorful beetles called melyrids were the origin of the hooded pitohui’s poison. “We found the same toxins in these beetles, and we found the beetles in the birds’ stomachs. These toxins would poison most other birds, so first you would have to evolve some resistance to the toxin yourself, and only afterward could it be of some use in defense,” says Dumbacher, highlighting just how tricky it is in evolutionary terms for a bird to render itself toxic. Because when you can just fly away, why go to all the trouble of maintaining your toxicity?
PART FIVE
ODD BODIES
A (Mostly) Vegetarian Spider
BAGHEERA KIPLINGI
“Okay, let me make this easy for you, Bagheera kiplingi. Who here hasn’t heard that you’re a vegetarian now? Absolutely no one? This is exactly my point, Bagheera kiplingi.”
A WIDE-EYED JUMPING SPIDER from southeastern Mexico and northwestern Costa Rica called Bagheera kiplingi is the first known mostly vegetarian spider. Discovered in the late 1800s and named after Rudyard Kipling’s Jungle Book panther, it wasn’t until 2009 that researchers, publishing in Current Biology, identified the unique eating habits that set it apart from the 40,000 other species of spider in the world. Instead of consuming the liquefied remains of insect, lizard, bird, or small mammal prey like most spider species, B. kiplingi prefers to eat whole plant material. (It does cheat, though, occasionally snacking on an ant, spider, or ant larvae.)
According to lead researcher and biologist Christopher Meehan from the University of Arizona, B. kiplingi is the first spider ever found to specifically “hunt” plants, treating them as a primary food source. “I’ve done the math several times, and even the most conservative estimates point to near-total vegetarianism.”
While some orb-weaving spider species have been observed eating pollen on occasion, it’s very rare to see a spider eat solid material such as leaves, particularly something like Beltian bodies. These detachable tips, found on some species of Acacia shrubs, are rich in lipids, proteins, and sugars, but are also 80 percent structural fiber, so are pretty bulky by a spider’s standards. “Spiders aren’t really thought to be capable of eating solid food at all,” says Meehan.
B. kiplingi has learned to take advantage of a special mutual relationship between the wasplike Pseudomyrmex ants and Acacia plants in which the ants protect the plant from predators and the plant supplies them with nutrient-rich Beltian bodies. By building their nests in the oldest, most withered Acacia leaves where the Pseudomyrmex ants are unlikely to patrol, B. kiplingi will use careful evasion tactics and its hydraulically propelled jump to make its way to a Beltian body and back to its nest undetected. If spotted, it will use a line of silk to drop to safety. Meehan also speculated that it might even be able to mimic the ants’ scent in order to mask its presence. “Jumping spiders in general possess incredibly advanced sensory-cognitive skills and eight-legged agility, and Bagheera is no exception,” he said. “Individuals employ diverse, situation-specific strategies to evade ants, and the ants simply cannot catch them.”
The Strangest Mammal in the World
NAKED MOLE RAT
(Heterocephalus glaber)
“You cannot hurt me, Mr. Bond. I am impervious to acid. I can’t get cancer. I can live in the foulest, darkest, deepest cave you find. You cannot touch me, Mr. Bond!”
“When was the last time you had sex with a female?”
“Well played, Mr. Bond. Well played.”
IT DOESN’T MATTER HOW well you think you know the naked mole rat, it will always end up being far weirder than you think. This is a cold-blooded, hairless, near-blind, bucktoothed rodent that can not only tolerate acid and chili heat, but can run backwards and resist cancer. Right down to their misshapen sperm and insectlike colonies, these might just be the strangest mammals on the planet.
Naked mole rats, otherwise known as sand puppies and saber-toothed sausages, are native to the harsh, drier areas of East Africa, including southern Ethiopia, Kenya, and Somalia. On average they grow to be about 4 inches long and 1 ounce in weight, and live almost 7 feet below the ground, densely packed into a complex system of pitch-black burrows. Here they happily breathe in oxygen-starved, carbon-dioxide–saturated air that would kill any other mammal; a naked mole rat tunnel has an atmospheric level of 10 percent carbon dioxide, while the normal atmospheric level of carbon dioxide is 0.04 percent.
Naked mole rats are one of just two species of mammals known to live in eusocial, or insectlike, colonies. Up to 300 naked mole rat individuals will live together in a colony, ruled over by a massive 3-ounce queen. Once she has literally shoved any contending females out the way, the queen will become the only female in the colony that can reproduce, selecting a single male as her mate. Most of the remaining “subordinate” males and all other females are reproductively suppressed for as long as the queen rules, but occasionally a subordinate male will father her offspring.
At the European Society of Human Reproduction and Embryology conference in 2007, Chris Faulkes from the School of Biological and Chemical Sciences at the University of London reported that the stress of the queen’s dominating behavior appeared to block puberty in the rest of the females, keeping their reproductive tracts underdeveloped. But Faulkes discovered that this phenomenon can be reversed—when the queen dies, the highest ranked of the remaining females will fight it out to find the new queen, who will very quickly become reproductively active.
By restricting the reproductive competition among the entire colony to one female, and one to three males, naked mole rat sperm has evolved to become simple, strange, and sluggish. In 2011, researchers from South Africa examined the sperm from males of different social statuses and found that not only did the sperm look weird, with irregular-shaped heads, poorly developed necks, and the smallest midpiece (the area at the base of the sperm head) of any known mammal, a dismal 1–15 percent of them could actually swim, and a mere 1 percent could be considered “fast” swimmers. By comparison, 70 percent of a dog’s, 60 percent of a stallion’s, and more than 50 percent of a human’s sperm will be healthy and forward moving. Somehow, despite the appalling mobility and structure of the sperm, the researchers found that the naked mole rat males could father a number of healthy offspring each litter.
With the protection of her entire colony, the queen can afford to have exceptionally long gestation periods of 70 days—rats have gestation periods of 20–24 days—and produce the biggest litters of any mammal, with an average of 28 pups five times a year. And according to Paul W. Sherman from
Cornell University in New York, they break all the rules when it comes to nursing. Mammals usually produce roughly half as many young in one litter as they have mammary glands, but naked mole rat mothers do the opposite. “Most mammals follow the one-half rule,” says Sherman, who published in the Journal of Mammalogy in 1999. “That is, they produce about one half as many young in each litter as they have mammae. In general, females have enough mammae for each young in the largest litters to have his or her own. It even works for humans, where our average litter size is one, but twins sometimes occur.”
Sherman and his colleagues suggested that the reason naked mole rats don’t have twice as many mammaries as pups is that infections could spread more easily with a large number of mammary glands. And despite the competition for food, the pups don’t seem to fight over the mammaries. They’ll quietly wait their turn or be nursed by another female in the colony. “This is one more reason why Heterocephalus glaber are so interesting to biologists,” says Sherman. “They live like social insects, the adults share food and defense tasks, they have the largest litters of any known mammal, they are closely related, and now, it appears, the young are willing to share mother’s milk. These animals have evolved to break the rules, because of their extreme sociality.”
They might not have a protective layer of fur or hair, and their skin isn’t particularly thick, but the naked mole rat has an incredible resistance to pain in its skin. While they react to temperature and pressure in the same way that other rodents do, they have evolved to lack a chemical in their bodies called Substance P, which is a neurotransmitter associated with certain types of pain. When a typical mammal sustains an injury or a burn that produces a long-lasting ache, the pain fibers that signal to their central nervous system will release Substance P, provoking a pain sensation. In 2008, researchers from Chicago and Berlin inserted a modified herpes cold sore virus into naked mole rats to deliver the genes for Substance P to the nerve fibers in one of their feet. Upon restoring the rodents’ sense of pain using this technique, the researchers tested their reaction to capsaicin, the active component in chilies, to all four feet. They found that only the foot with Substance P in its nerve fibers provoked a reaction.