Zombie Birds, Astronaut Fish, and Other Weird Animals

by Becky Crew

  PART FOUR

  PREY

  Cliff-Diving Toad

  VENEZUELA PEBBLE TOAD

  (Oreophrynella nigra)

  LAUNCHING YOURSELF OFF A cliff face at the sight of a predator might look exactly like suicide, but when you’re a Venezuela pebble toad this is actually the perfect getaway.

  In the Guiana Highlands of South America, which run through Venezuela, Guyana, and Brazil, sheer, flat-topped pillars loom above misty cloud forests. These strange mountains, known as tepuis, are so tall and inaccessible, some reaching over half a mile above the forest floor, that they have their own unique climates and ecosystems, supporting endemic species that are found nowhere else on Earth. Multiple sinkholes 984 feet deep and 984 feet in diameter spot the surface of the tepuis, each containing their own unique species.

  Venezuela pebble toads thrive on the tepuis, but it isn’t easy—they can’t hop or swim, and while their warty, dark grey skin camouflages them against the mountain rocks, they lack the advantage of the bright colorings that many frogs and toads use to warn predators away from eating them, whether or not they’re actually poisonous. Plus at no more than 1.2 inches in length, they are also extremely small, making them the perfect snack for the tarantulas and scorpions that stalk the surface. Fortunately, these tiny bodies are the very things that keep the pebble toads alive.

  When threatened by a predator, the pebble toad will roll itself into a ball and throw itself off the side of the mountain, bouncing down the rocky walls until it lands on a flat surface below. It will often tumble for many feet, but because it keeps its incredibly light body so rigid and its muscles so tense, the impact of the fall is too minor to cause it any injury. The pebble toad simply gets up and ambles away. The only time this escape strategy fails is if the pebble toad accidentally lands in a puddle that is too deep to crawl out of and it drowns.

  This behavior was discovered for the first time by ecologist and director of the Coastal Plains Institute and Land Conservancy in Florida, Bruce Means, who is one of the world’s foremost experts on the pebble toad. In 2009, he escorted a two-man camera crew from the BBC to the surface plateau of a tepui to film documentary footage. Means had previously observed the same behavior in the thumb-sized waterfall toads (Oreophrynella macconnelli) that inhabit the dense, fog-covered cloud forests that skirt the tepuis. When a predator is near, the waterfall toad will launch itself from whatever branch or leaf it is sitting on and tumble until it grabs onto something below with its oversized Mickey Mouse–esque hands and feet. Like the Venezuela pebble toad, the waterfall toad can’t effectively jump, so falling is the most effective method to get far away from lurking tree snakes or spiders.

  Means examined the enormous hands shared by the waterfall and pebble toads, commenting that while they’re perfect for grasping onto leaves and branches during a tumble through the cloud forest, they’re not so useful on the flat tepui summits. So why do the pebble toads have them at all?

  The tepuis were formed over millions of years as persistent wind and rain combined with the movements of the Earth’s crust to erode and elevate South America’s expansive sandstone plateau. Gradually, hundreds of towering pillars were formed and the waterfall toads likely rode up with them from the cloud forests below. Over the millennia, the waterfall toads have evolved into a number of summit-dwelling pebble toad species, each suited to their own tepui’s particular environment, but have retained their ancestors’ most important instinct—leap or be lunch.

  “I’m going to be honest, Pebble Toad, I like you for this position. But I’m a little concerned about the number of employers you’ve had over the past twelve months. And I can’t see any position here that’s lasted longer than a month. Can you explain?”

  “I’m too ambitious? I’m overqualified? Hold on, let me just get my list of references for you.”

  “Why is your briefcase filled with dirt?”

  “Okay, fine! I’m lying! I can’t keep a steady job because I move around all the time. But do you have any idea how hard it is to set yourself up in a new town every time you fall down a cliff because someone wants to eat you? You see these goofy hands? You’d think I’d be able to climb back up with these, and I probably could, but it’d take me months, and by that stage someone else would have already moved into my house and taken my job as a movie ticket vendor because unlike me, they probably don’t need to sit on ten stacked telephone directories just to see out of the booth. Do you mind if I smoke in here?”

  “Mr. Toad, I’m not sure—”

  “Not to mention my wife wants to know why I have so many exes posting angry comments on my Facebook wall, and my friends want to know why I never RSVP to anything anymore. And you’ve seen my resume. God forbid I ever try actually having a family. Leave that, they’ll call you back.”

  “Mr. Toad, I need to take this call.”

  “I should probably just embrace the lifestyle, you know? Become an outlaw or something. But I couldn’t steal shit because what’s the point? It’s not like I can take anything with me. You know my brother died last year? Fell into a puddle at the bottom of a jump. They say it was an accident, but I’m not convinced. You got any snacks?”

  “Mr. Toad, I like you. I’d like to offer you this job, but—Stop! Shit. Grace! Get in here!”

  “Sir? What happened to your candidate?”

  “Jumped straight through the window. Damndest thing, I was about to tell him he had the job, but I couldn’t offer him an office with a window.”

  “I’ll get someone to clean up the glass.”

  “You’re a doll.”

  Transformer Butterflies

  NUMATA LONGWING BUTTERFLY

  (Heliconius numata)

  “Doug, you march right back into your room and don’t come out until you look disgusting. Do I look like I’m joking? One more ‘But Mum’ and you won’t be going to the dance at all. I won’t have you killed just because you want to impress the girls by not being disgusting.”

  IN APRIL 1848, HENRY Walter Bates joined fellow British naturalist, explorer, and amateur entomologist Alfred Russel Wallace in an expedition to the Amazon rainforest to solve what Bates called “the problem of the origin of the species.” It was at this time that many scientists in England, including Thomas Henry Huxley, Richard Spruce, and Charles Darwin, were developing the theory of evolution by natural selection, which in its most basic form claimed that life progresses from being simple to highly complex over time.

  Wallace and Bates arrived at a hut in a region of Brazil called Ega (now known as Tefe), where they split up to explore the Amazon separately. Bates worked with Amazonian butterflies for the next eleven years. Returning to London in 1859 with some 14,000 specimens, Bates, a relatively unknown scientist at the time, found himself broke. It was Darwin, who had published On the Origin of Species that same year, who threw him a lifeline, helping him find a job at the Royal Geological Society in 1864. In return, Bates provided Darwin with the first real evidence for natural selection, known as insect mimicry.

  When Bates and Wallace were in the Amazon, they noticed that different species of butterflies were mimicking each other’s wing patterns. Bates proposed that certain species of butterflies had evolved the ability to change their appearance to ward off predatory birds. Named “Batesian mimicry,” this phenomenon describes the ability of a palatable species to mimic an unpalatable or noxious species.

  Around the same time, German zoologist Johann Friedrich Theodor “Fritz” Müller was working with a species of long-winged brown, golden, and yellow Amazonian butterfly called the Numata longwing butterfly (Heliconius numata). Publishing his findings in 1878, Müller reported that the Numata longwing butterfly was able to morph into seven different wing patterns, each identical to the wing patterns of a separate group of butterflies, the toxic Melinaea. The difference here was that both species of butterflies were inedible. Müllerian mimicry reasoning poses the question: Why should prey animals employ a number of different warning s
ignals—each of which must be learned by predators through experience—instead of everyone just using the same warning signal? If a number of prey species agree on a common warning signal, it would take predators a much shorter time to learn not to target any of them.

  Exactly how butterflies are able to morph themselves into having different wing patterns took another 150 years to figure out. In 2011, scientists from France and England reported in Nature that they had discovered an incredible cluster of about thirty genes in a single chromosome in Numata longwing butterflies that is responsible for their mimicry. Named a “supergene,” this cluster contains several genes that control the different elements of wing patterns, and the scientists found that three versions of this same chromosome coexist in the species. By changing just one gene, Numata longwing butterflies are able to look identical to another species but look completely different from each other, even though they share the same DNA.

  So if these two kinds of butterflies have found success against predators in looking the same, why would they need seven different forms? Why not just use the one form of wing pattern to make things easier for predators to remember? Ecologist Mathieu Joron from France’s Muséum National d’Histoire Naturelle, lead author of the Nature paper, suggested that each of these wing patterns has proven so successful in warning the birds and lizards away that there is not much selective pressure for the wing patterns to converge. Another possibility is that the butterflies could belong to different microhabitats, in which different patterns are more successful than others.

  The team also discovered the same supergene in the peppered moth, which can be found in Europe and North America. In nineteenth-century Britain, when the industrial revolution rendered everything a sooty shade of grey, the peppered moth changed from having a light-colored wing pattern to having black wings, which allowed them to blend with their new environment.

  Don’t Get Angry: Vomit

  EUROPEAN ROLLER

  (Coracias garrulus)

  THE SMELL OF FEAR might sound like abstract nonsense, but the phenomenon of emitting detectable odors in response to a threat spans the smallest insects to the bravest humans.

  In late 2008, researchers from Stony Brook University in New York investigated the underarm secretions of twenty novice skydivers before they did their first tandem jump to see if their sweat held any clues about the human fear response. Volunteers were asked to sniff the sweat that was collected in the skydivers’ clothing during the jump, plus the sweat collected while the skydivers ran on a treadmill for a similar length of time on the same day. In order to eliminate bias, the volunteers were not told what the study was about. An analysis of the volunteers’ brain activity while sniffing the two types of sweat revealed that their amygdala, the brain region associated with fear memory and response, was more active when they sniffed the skydiving sweat. Publishing their findings in PLoS ONE the following year, the team suggested that humans have some kind of signaling system whereby emotional stress can be sensed via the chemicals that are emitted during a frightening situation.

  Elsewhere in the animal kingdom, fear signals are a whole lot less subtle. There are plenty of examples in the avian world of birds that secrete certain chemicals for the specific purpose of deterring would-be predators. The northern fulmar (Fulmarus glacialis), a gull-like seabird from the north Atlantic and north Pacific, expels projectile stomach oils at predatory birds to mat their plumage and strip it of its waterproofing, and large, striking sea ducks called common eiders (Somateria mollissima) spray feces on their feet during incubation season when threatened in order to deter predators from their eggs.

  But do birds ever produce a chemical response to fear that is designed to warn those of the same species of a threatening situation, rather than to deter predators? The European roller (Coracias garrulus) is a migratory, cavity-nesting bird whose range extends through northwest Africa, Europe, parts of the Middle East, and central Asia. Crow sized but stunningly colorful, they are adorned with iridescent kingfisher-blue plumage capped with tawny upper parts and shocks of azure along the front edge of their wings. As nestlings, they vomit pungent orange liquid on themselves when threatened.

  Researchers from the Estación Experimental de Zonas Áridas in Spain decided to investigate the exact function of this vomit, to figure out if it acts simply to deter predators or to communicate a message amongst the rollers. They also wanted to discover to what degree the birds are using their sense of smell to defend themselves. After selecting a number of nests with ten-day-old nestlings inside and measuring the level of attentiveness their parents paid to them, the team painted 1 milliliter (0.2 tsp) of either roller vomit or lemon essence on the insides of the nests. By applying very similar-looking liquids, they could effectively test the birds’ sense of smell.

  The researchers, led by evolutionary and behavioral ecologist Deseada Parejo, reported that the parent European rollers returning to the vomit-laced nests exercised far more caution, and took much longer to settle back in. “Indeed, the supposedly defensive liquid which nestling rollers vomit when disturbed is smelled by parents so that they can adjust their behavior to avoid predation,” they reported in a 2012 issue of Royal Society Biology Letters. So it seems that the vomit is a mechanism by which the nestlings can inform their parents of a threat that occurred while they were on a hunting trip. A further advantage of the vomit could be that it makes the nestlings undesirable food for predators, which in turn increases the parents’ chance of survival.

  Don’t think I can’t see what’s really going on here, European roller nestlings. Sure, it looks like a clever survival mechanism, but as if you’re not just trying to cover yourselves for all the ridiculous parties you have in your nest while your parents are out finding food. For you, nestlings. Wait, you’re not? Why wouldn’t you?

  Think about it: One night you’ll all be like, “Quick, Steve: are your parents gone yet? Get the hell over here, we’re playing strip poker!”

  And Steve will be like, “Wow I didn’t know anyone actually plays strip poker. Definitely not interested in that, Multiple Joeys from Friends.”

  ZING, nestlings!

  So you’ll have to wait till your parents go out again to try to throw your amazingly cool party, and this time you’ll actually follow the number one rule when it comes to throwing amazingly cool parties according to every teen movie ever—you need to supply the alcohol. And then all you’ll need to do when your parents call and say they’re on their way home is tell everyone that you’re running out of alcohol so they’d better drink whatever they can get their hands on real quick. And then, nestlings, just sit back and wait for the vomits to arrive.

  This will buy you some valuable time, because your parents will have to wait it out at some bar because of the “predators,” so you can keep trying to hit on Steve’s little sister and all her friends. Although they have all just vomited on themselves, nestlings, so it depends on how desp—Oh. Almost forgot who I was talking to for a second.

  Poison-Blood–Spitting Eyes

  TEXAS HORNED LIZARD

  (Phrynosoma cornutum)

  “All right, so I don’t care if you’re handsome or smart or even nice at this point. But let’s just get a few things straight. If we do end up in a relationship, there will be no surprise parties, no unannounced tickle fights—or announced ones for that matter—and when I have the hiccups, for god’s sake don’t try any ‘fright’ tactics. Unless you think a girl shooting blood out of her eyes is a turn-on, in which case we might have something (but we won’t, because I’m not interested in creeps). If you think all of that sounds reasonable, let’s do coffee. Oh, and must hate dogs. x”

  “Hi Texas Horned Lizard, you look cute in your profile pic, where is that, Kansas? Anyway, I don’t want to sound presumptuous, but I think we could get along pretty great. I do gross things with my ribs when I’m scared and I’m embarrassed about it too, so let’s just drink tea and watch Seinfeld and play board games. The least scary date in
the world. And if the neighbor’s dog suddenly barks, or the wind slams a door shut, or my idiot housemate turns a blender on in the kitchen without warning, my ribs will explode and you’ll shoot blood out of your eyes, and we’ll laugh about it and then have more tea. That doesn’t sound too bad, right? Spanish Ribbed Newt. xo”

  WITH A BLUNT FACE framed by a halo of horns and a flattened, tanklike body, the Texas horned lizard (Phrynosoma cornutum) looks like a tiny dragon. With the biggest males growing to almost 4 inches in length, it is the largest of the fourteen species of horned lizard spread across the western United States and Mexico, and is one of three horned lizard species that can shoot jets of poison blood from its eye sockets when threatened.

  Known as “autohemorrhaging” or “reflex bleeding,” this behavior is exceptionally rare in vertebrates. The only other known species to do it are Tropidophis, a dwarf boa that squirts blood from its mouth, nostrils, and eyes, and Natrix natrix, a grass snake that secretes blood from its mouth and nose to convincingly play dead when faced with a predator.

  The Texas horned lizard autohemorrhages to both confuse and ward off predators such as coyotes, hawks, and domestic dogs. It obtains its poison from a diet of insects, specifically harvester ants (Pogonomyrmex), which carry one of the most toxic natural venoms known in the world. This means the lizard has had to evolve a complex method of capturing and swallowing these ants so they don’t harm its mouth, pharynx, or stomach with their venom.