Archives

Mozambique Diary: Not all flies fly

Tsetse fly (Glossina sp.) from Gorongosa feeding on my blood. Luckily, tsetses in this area do not carry the dreaded sleeping sickness (but it does not make it any less painful).

Tsetse fly (Glossina sp.) from Gorongosa feeding on my blood. Luckily, tsetses in Gorongosa do not carry the dreaded sleeping sickness.

After a long hike in the scorching heat of the African savanna the cool, shady patch of tall miombo forest looked like heaven to us. I was in the southern part of Gorongosa, looking with a few friends for some elusive species of arthropods. But we were having little luck finding any and after several hours of strenuous walking the morale was low. As we stepped under the dark, inviting canopy of the forest, the drop in the temperature was palpable and we all relaxed, slowed down the pace, and the mood in the group immediately improved. But then, suddenly, somebody yelped “Ouch!” and at the same moment I felt a painful pin-prick at the back of my neck. Crap, tsetse flies! We looked around – they were everywhere. Clouds of them. We could see groups of dozens clumping on vegetation, taking into the air the instant they noticed the movement of our bodies. We ran.

A painting (undoubtedly the first and only) of a bat fly (Penicillidia sp.) burrowing in the fur of a Long-winged bat (Miniopterus).

A painting (undoubtedly the first and only) of a bat fly (Penicillidia sp.) burrowing in the fur of a Long-winged bat (Miniopterus).

Tsetse flies have long had a reputation for being one of the scourges of Africa, alongside malaria, crocodiles, and the plague of locusts. And deservedly so – some species of tsetses, all members of the genus Glossina, are vectors of nasty protozoans, including Trypanosoma brucei, the cause of the deadly sleeping sickness. Luckily for us, Gorongosa tsetses carry a different Trypanosoma species, T. congolense. This protozoan does not affect humans but unfortunately causes the chronic Nagana disease in cattle and horses, which explains the nearly complete absence of these animals around the park and in almost the entire region of central Mozambique. But knowing that tsetse bites are not going to kill us did not make them any more pleasant. Tsetses are large flies, about the size of a bee, and their skin-piercing mouthparts are much thicker than those of a mosquito. In other words, it hurts like hell when one jabs you with its proboscis, and you flail your arms like a madman to shoo it away while the fly escapes unharmed.

Members of the family Streblidae, such as this Raymondia sp., collected from the Hildebrandt's horseshoe bat (Rhinolophus hildebrandtii), often exhibit interesting adaptations in their wing morphology, such as the ability to fold them longitudinally along the back. This presumably helps them move swiftly in the pelage of their hosts.

Members of the family Streblidae, such as this Raymondia sp., collected from the Hildebrandt’s horseshoe bat (Rhinolophus hildebrandtii), often exhibit interesting adaptations in their wing morphology, such as the ability to fold them longitudinally along the back. This presumably helps them move swiftly in the pelage of their hosts.

But count yourself lucky. Imagine instead that you cannot shoo them away. You try to smack one but it runs, hides in your hair or some place where you are not able to reach, and it continues to bite. It only leaves your body to give birth somewhere in your house but then immediately runs back, guided by your scent and body heat. Oh, and imagine that this fly is the size of your fist (or a small puppy). Welcome to the world that bats are forced to live in.

Tsetses are members of a large group of flies, the superfamily Hippoboscoidea, all of which are exclusively hematophagous – blood is the only food that they are interested in. The tsetse family (Glossinidae) is the most basal (unsophisticated, one might say) member of this lineage of insects – they are always looking for a blood meal but never evolved the ability to stay with their tasty host. Bats are unlucky to have been colonized by two much savvier families of flies, the Nycteribiidae and Streblidae. These insects know the value of a good host and, once they landed on the furry back of a bat, they never leave it again. Over millions of years of coevolution with their mammalian hosts the bat flies have undergone a remarkable transition. From a free-flying ancestor, most likely very similar to today’s tsetse flies, emerged several lineages of highly modified, often completely wingless, spider-like creatures. Their body became flattened and very hard, making it almost impossible to squash them against the skin. In the family Nyctiberiidae the head turned into a small appendage that can be safely tucked away in a protective groove on the back and all traces of wings completely disappeared. These flies cannot survive for long outside of their host’s body and only feel at home when scurrying at an alarming speed in its dense fur. Their feet are armed with large claws that make it almost impossible to dislodge them from the hair of their host. They really don’t look like flies and when a friend spotted one on the body of a bat she called me to collect the bat’s “pet spider.”

In the closely related family Streblidae the wings may or may not be present, but even in the winged species the body is modified for squeezing through the fur, and members of the subfamily Ascodipterinae go even further in their commitment to the host. Much further. Once a female lands on a bat she sheds her wings and legs (yes, legs) and burrows head-first into the skin. Once there, her head and thorax sink into her own abdomen, and the skin of the bat overgrows her body. She becomes one with her host.

Penicillidia bat flies (Nycteribiidae) are some of the most unusual members of the order Diptera and hardly resemble their winged relatives. This individual was collected from a Long-winged bat (Miniopterus natalensis) in Gorongosa, Mozambique.

Penicillidia bat flies (Nycteribiidae) are some of the most unusual members of the order Diptera and hardly resemble their winged relatives. This individual was collected from a Long-winged bat (Miniopterus natalensis) in Gorongosa, Mozambique.

Female bat flies, like their relatives tsetse flies, are remarkably good mothers. The great majority of insects relies on what ecologist call “r-selection” in their reproduction – they lay hundreds or thousands of eggs, betting on one or two of them making it to adulthood. Bat flies, on the other hand, rely on “K-selection” – like humans, they prefer to invest a lot in a much smaller number of offspring, hoping that they will all make it to the reproductive age. They are larviparous – instead of laying eggs the female gives birth to a single, fully developed larva, which immediately turns into a pupa. While in her mother’s body, the larva feeds on “milk glands”, analogous to the mammalian mammary glands (if they were located in the uterus), and develops safely protected from the elements and predators. When the time comes for the mother to give birth she walks off the bat’s body and attaches the larva to the wall of the bat’s roosting place, usually a cave (which explains why bats that roost in rolled-up leaves and other less permanent places have fewer ectoparasites). Then she turns back and runs towards her host, guided by the smell and the heat of its body.

The recent Ebola crisis brought back the attention of the medical community to bats as potential reservoirs of the virus. Although there is no evidence that bats are in fact harboring the virus, there seems to be some correlation between instances of the outbreak and the presence of large numbers of bats in the affected areas. While reading the literature on both Ebola and bat flies I found it rather curious that nobody has tested bat flies for the presence of the virus – these are relatively very long lived (195 days on average) insects, who always stay (as pupae) at the roosting sites of bats, even when the hosts leave to forage elsewhere. They often move from one host species to another and, this point makes me really wonder why nobody has seriously looked at these flies as potential vectors, occasionally drop on and bite people. We know that they harbor a slew of pathogens – a recent study conducted in Gorongosa National Park on bats Rhinolophus landeri and Hipposideros caffer showed that flies living on these animals are vectors of Trypanosoma species that are ancestral to those that cause Chagas disease. Add to this the fact that one of the first cases of Marburg disease in Zimbabwe (caused by a virus related to Ebola) was caused by a bite of an arthropod (by default all unidentified bites seem to be classified by the medical community as “spider bites” and spiders in the area were tested, predictably unsuccessfully, for Marburg). It is far more likely that the bite was caused by a fly that fell off a bat.

A friend of mine recently expressed her dismay at “lowly” parasites. I beg to differ – if anything, parasites, including bat flies, are incredible examples of evolution at its best, organisms capable of both adapting to life in the most hostile of environments (the very substrate you live on wants you dead!) and resisting diseases that live inside your body. I cannot promise that I will not try to smack the next tsetse fly that lands on me but at least I promise that I will do it in the most respectful, considerate way.

Louse flies (Hippoboscidae) are close, equally modified for ectoparasitic lifestyle family of flies. This Lipoptena sp. was collected from a Nyala antelope while it was fitted with a GPS collar. Louse flies are parasites of large mammals and birds, and some are considered serious pests of sheep.

Louse flies (Hippoboscidae) are closely related to bat flies and equally modified for ectoparasitic lifestyle. This Lipoptena sp. was collected from a Nyala antelope while it was being fitted with a GPS collar. Louse flies are parasites of large mammals and birds, and some are considered serious pests of sheep.

Mozambique Diary: Rescuing a Dragon

A guest post by Jen Guyton

In my lap was a specter, one of the most elusive animals in sub-Saharan Africa. I’d been waiting years to see it, and now it was weighing abrasively on my thighs like a sack of bricks stuffed into a giant pinecone. It wiggled and unfurled its roly-poly body just enough to reveal an eye like sticky caviar, its tongue whizzing in and out and reinforcing the illusion that this scaly orb was a dragon come to life.

Jen_Guyton_painting

But it was a warm-blooded, placental mammal, confirmed by the tiny body double that was furled in her grasp, suckling at the teats exposed on her underbelly. The mother and her pup were ground pangolins (Smutsia temminckii), one of eight species belonging to the mammalian order Pholidota, found only in Africa and southeast Asia. Though often called scaly anteaters, pangolins are unrelated to the Vermilingua, the suborder containing true anteaters. Actually, pangolins aren’t closely related to much of anything; these animals are unique, clinging to a long, isolated branch on the tree of life.

Safe at last – rescued from poachers, a Ground pangolin and her baby boy are going back to Gorongosa National Park to be released back into their habitat.

Safe at last – rescued from poachers, a Ground pangolin and her baby boy are going back to Gorongosa National Park to be released back into their habitat.

We were in Gorongosa National Park, Mozambique, and someone had told us about her. There was a man in a village across the river, the whispers went, selling her for the low price of 22,000 meticais (about $700 USD). Like rhinos, pangolins have fallen victim to a deeply-held misconception that their keratinous scales hold medicinal magic: that they can cure skin disease, reduce swelling, or even conquer cancer. I’ll tell you now: save yourself the money and the risk of jail time, and just chew on your nails – they are chemically and physiologically the same.

One day and a sting operation later, the pangolin was in my lap. Park rangers, working with the local police, arrested the poachers and rescued the animals. We were driving them out into the core of the park, where we’d release them, safely distant from grasping human hands. Though the pinecone plates of a pangolin’s back can and do stand up to being chewed on by lions, these animals are no match for a human that’s interested enough to simply pick one up and carry it off. Their only other defense is their smell, an indescribable odor that originates from a noxious acid secreted from glands below the tail.

I ran my hands along the pangolin’s scales. They were grooved and brittle-chipped, crooked and mud-splattered like fingernails that had seen many years of working with the land. In Asia, the scales of confiscated pangolins bear the circular scars of punches used for medicine. Even the artful hand of evolution, which had crafted this unique armor from a plush pelt, couldn’t save them.

Bipedal and armed with massive claws, a Ground pangolin could easily be confused with a carnivorous Jurassic raptor. But these gentle mammals feed exclusively on termites and ants, and their only defense is a thick armor of keratinous scales.

Bipedal and armed with massive claws, a Ground pangolin could easily be confused with a carnivorous Jurassic raptor. But these gentle mammals feed exclusively on termites and ants, and their only defense is a thick armor of keratinous scales.

As she unrolled herself from her fortress, a second head surfaced, tiny and pale. It was her male pup, the only one that will be born until he reaches sexual maturity in two years. He was born in captivity, a side effect of stress, and an unrealized bonus prize for the poacher. His scales were half-baked, pliable, and the dark shriveled stump of an umbilical cord poked from his round belly. He moved in the shivering stutters of an infant still unsure about the world.

As the pup crawled up my arm, the mother thrust out a hooked hand to right herself. Her claws, the length of my fingers, gripped my jacket like rusty nails and tore a gaping hole in the material as they bore into my side. I jumped, and she rolled back into a ball, her pup safely inside. These formidable sickle-claws are used to tear open termite mounds and ant nests, shredding the hard earth in search of scrambling adults and doughy larvae. The pangolin laps them up with its sticky-salivating tongue, longer than its own body and the longest relative to body size of all known mammals. Because pangolins lack teeth entirely, keratinous folds line their stomachs with inverse armor, grinding the insects to bits with the help of ingested pebbles.

Having spent a month in captivity, the pangolin, her baby tenuously clinging to her back. takes the first steps as a free animal.

Having spent a month in captivity, the pangolin, her baby tenuously clinging to her back, takes the first steps as a free animal.

We finally reached an appropriate site: far from the park’s perilous edges, the forest bulged above a tapestry of termite mounds. We set her gently on the ground, and waited.

Pup clinging to her back, she stood and sniffed the air, taking a few moments to orient herself to her new and safer home before choosing a bearing. Her scales clack-clacking, she ambled away on her hind feet like a drunken Velociraptor, tail out and claws curled against her chest. It’s hard to walk on all fours when you’ve got scythes for hands.

In Chinese mythology, pangolins are wayfarers. It’s said that they travel the world by digging through the core of it, tying the earth together with a vast underground labyrinth. In Cantonese, they’re called chun-shua-cap, “the animal that bores through the mountain.” I’d like to think she’s safely reached the Alps by now.

Text and artwork ©Jen Guyton 2014

If you would like to learn more about pangolins, and threats they face from the illegal wildlife trade, read a recent expository piece on the CNN website.

Safe under his mother's armor, a young pangolin will stay with her until his own scales are large and strong enough to provide protection from predators.

Safe under his mother’s armor, a young pangolin will stay with her until his own scales are large and strong enough to provide protection from predators.

Mozambique Diary: Amphisbaenians

Most people would hardly look twice at this small, pink “worm”, but this amphisbaenian (Chirindia swynnertoni) from Gorongosa probably looks like the now extinct ancestor of all snakes.

Most people would hardly look twice at this small, pink “worm”, but this amphisbaenian (Chirindia swynnertoni) from Gorongosa probably looks like the now extinct ancestor of all snakes.

Having drawn the short straw at the phenotypic lottery I have always felt a special kinship with creatures that most people dismiss as too small, too creepy, too unattractive. Because these are (I tell myself) the hallmarks of the truly interesting organisms, ones that have followed the less-trodden paths of unusual specialization, remarkable adaptations, evolutionary ingenuity.

One such organism, about the existence of which I learned as a young child from an old zoology textbook, was Bipes, an amphisbaenian. It was a chimeric, strange creature, with the appearance of a pink snake, but equipped with a pair of shovel-like legs at the front end of its long body. There was a striking resemblance between that creature and a picture of a dragon that I had seen in the illustrated edition of the Old Testament from my Sunday School (which, incidentally, offered its classes on Monday nights), and I was instantly hooked.

Although it looks like a soft and squishy, the amphisbaenian’s head hides a strong skull that allows it to push through even the hardest soil.

Although it looks soft and squishy, the amphisbaenian’s head hides a strong skull that allows it to push through even the hardest soil.

Amphisbaenians are reptiles, but so unusual that for the longest time they were considered a separate order of these animals. For one, they look nothing like a vertebrate – the last couple of times that somebody brought me an amphisbaenian they were under the impression of having collected an earthworm (unlike Bipes, most species are legless.) Their annulated body is usually pink or covered with irregular, white and dark blotches, a clear indication that these animals don’t care about how they are perceived by others. And for a good reason – why bother with the looks if your entire life is spend underground and you yourself are blind. Better to invest the energy that would have been spent on the irrelevant appearance into things such as a thick skull and powerful thoracic muscles that will allow the animal to push effortlessly though the soil in search of prey.

My assistant Ricardo Guta looking for insects and other animals in the habitat of the Gorongosa amphisbaenian.

My assistant Ricardo Guta looking for insects and other animals in the habitat of the Gorongosa amphisbaenian.

Recent phylogenetic studies revealed that amphisbaenians are not a separate, primitive order of reptiles, but rather a highly derived, supremely modified lineage of lacertiform lizards. It is very likely that the next step in this transition to a subterranean lifestyle was the complete loss of limbs and girdles, a dramatic reshaping of the skull, the loss of eyelids and, eventually, the emergence of a brand new group of animals, the snakes. In fact, the most basal (primitive) snakes, the Typhlopidae and other related families, look remarkably like the amphisbaenians.
A few days ago I was in the southern part of Gorongosa, checking out sites for the second biodiversity survey of the park, and there, in a dry, crumbling log, I found a beautiful little amphisbaenian, Chirindia swynnertoni. This species is rarely seen, and thus I promptly followed a recommendation of a field guide to amphibians and reptiles of East Africa: “Anyone finding a worm-lizard [amphisbaenian] should take it to a museum.” I still haven’t had the heart to preserve it for the Gorongosa Synoptic Collection, and instead I have been watching it for days, transfixed by its amazing ability to squeeze into the hardest soil with the body that looks like an overcooked string of pasta, and with a baby-pink face of a newborn. It has been feeding on termites and ant larvae, crushing the insects with its tiny yet powerful jaws. And I find it fascinating (and somewhat rewarding) that from so seemingly unassuming a beginning came a lineage of animals that has terrified the human psyche since the time of Eden.

Gorongosa amphisbaenian (Chirindia swynnertoni)

Gorongosa amphisbaenian (Chirindia swynnertoni)

Mozambique Diary: Shooting bats

Leaf-nosed bats (Hipposideros sp.) in a cave of Cheringoma Plateau, Gorongosa National Park.

Leaf-nosed bats (Hipposideros sp.) in a cave of Cheringoma Plateau, Gorongosa National Park.

My entire last month was a blur of hectic activity, related mostly to the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa National Park. This kept me from updating the blog, but it was definitely worth it – the Lab is a fantastic facility that will serve as a research base to current and future scientists in the park, and as a center of advanced biodiversity education for Mozambican students for years to come (I just finished teaching its first African entomology workshop there, and it was great.) We are also creating the Gorongosa Synoptic Collection, which has the ambitious goal of documenting, over the next 15-20 years, all (or at least as much as physically possible) multicellular diversity of the park – I will try to post frequent updates from this effort. In the meantime, I would like to invite all biologists to come and work in Gorongosa – there is an entire universe of unexplored life out there, waiting to be studied and saved. Contact me if you are interested – Gorongosa wants your research projects, and we will help you make them happen.

Slit-faced bat (Nycteris cf. thebaica) from Gorongosa and a sonogram of its echolocation.

Slit-faced bat (Nycteris cf. thebaica) from Gorongosa and a sonogram of its echolocation.

One of the many benefits of having a permanent and safe logistical base in a place as biologically rich as Gorongosa is that I am not afraid to bring and leave behind my expensive high tech gear, and experiment with it. For months I had been dying to try out my high speed photography system, and finally was able to use it last month to shoot flying bats in the comfort of our lab. Now, bats have been photographed in flight by many, and the technology to do so has existed since at least the 1980’s. But, as far as I could tell, few had tried to take images of flying bats using the white background technique, made popular by the Meet Your Neighbours project, and I really wanted to try it.

An orange form of a Horseshoe bat (Rhinolophus landeri) from Gorongosa and a sonogram of its echolocation.

An orange form of the Horseshoe bat (Rhinolophus landeri) from Gorongosa and a sonogram of its echolocation.

The setup for photographing bats in flight will be familiar to anybody who has ever worked with high speed photography: I used an external, very fast shutter (6mS response time, 10-50 times faster than the shutter in a typical SLR) mounted on a Canon 7D with a 100mm macro lens, triggered by two intersecting laser beams, and with four Canon flash heads that provided the illumination. Cognisys is a company that sells turnkey solutions for high speed photography, and their excellent StopShot system is what created the basis of my setup. The tricky part was to create a stage where the bats’ flight path was relatively narrow, allowing me to illuminate it properly. Last year I photographed bats in a cave, which was relatively easy, but gave me little control over the lighting. I needed to restrict their movement better, and decided to bring a large diffusion box that I would then turn into a flight chamber for the bats.

The box was about 1 m (3 ft) long, giving even the largest Gorongosa species ample room to fly. On the sides of the box I cut out two small windows (covered with thin, clear Perspex) that allowed the laser beams to go through. The front of the box had to remain unobstructed to the lens, but something had to stop the bats from flying out; I ended up using a large piece of thin glass (and had to adjust the flashes so that they would not reflect off the glass). But somebody had to put the bats in there, and it was not going to be me (one word – rabies!)

Leaf-nosed bat (Hipposideros caffer) from Gorongosa and a sonogram of its echolocation.

Leaf-nosed bat (Hipposideros caffer) from Gorongosa and a sonogram of its echolocation.

Luckily, I got help from Jen Guyton, a Princeton graduate student and a bat specialist, who is working on her Ph.D. in Gorongosa. Since capturing bats to get samples of their DNA (or rather the DNA of their prey) was part of her nightly routine, Jen was able to bring live bats to my studio and control them while I took the photos. Once all the technical kinks were ironed out, the system worked like a charm – in a few minutes I would get multiple shots of each bat, and then the animal was removed from the chamber unharmed.

A studio setup for photographing bats in flight: (1) Cognisys high speed shutter, mounted on Canon 100mm lens; (2) a laser and a laser beam sensor (an identical but vertically reversed set is positioned on the opposite side of the box).

A studio setup for photographing bats in flight: (1) Cognisys high speed shutter, mounted on a Canon 100mm lens; (2) a laser and a laser beam sensor (an identical but vertically reversed set is positioned on the opposite side of the box).

But some species turned out to be more difficult than others – members of the family Molossidae (my favorite bats) are not able to lift off from horizontal surfaces and thus could not fly in the box. Next month I plan to photograph them in the wild by combining this system with a UV light – I hope that the bats will be attracted to insects coming to the light (which they often are) and sooner or later will hit the laser trigger. Watch this space to see if it worked.

One final note – don’t try any of this at home! Nobody but professionals, vaccinated against rabies, legally permitted, and fully trained to handle live bats should ever attempt catching these animals. If you are interested in photographing bats, get in touch with a mammalogist at a nearby university or a conservation group that works with these mammals, and they may be able to help you. They are an awesome group of animals, but don’t risk their or your own life. Having seen Gorongosa bats’ unbelievably sharp, lyssavirus-carrying teeth in action, I now think of them as flying vipers – cool, beautiful and fast and, potentially, very deadly.

A grey form of the Horseshoe bat (Rhinolophus landeri) from Gorongosa

A grey form of the Horseshoe bat (Rhinolophus landeri) from Gorongosa

 

Mozambique Diary: The House of Spiders

A guest post by Edward O. Wilson

The skeletal remains of the Hippo House, once a busy restaurant and observation point.  Orb weaver (Nephilengys cruentata) from the Hippo House.

The skeletal remains of the Hippo House, once a busy restaurant and observation point.

Each spider in the Hippo House was sheltered in a tubular retreat, a behavior typical of all species in the genus Nephilengys.

Each spider in the Hippo House was sheltered in a silken, tubular retreat, a behavior typical of species in the genus Nephilengys.

At the end of a long rutted road in the park sits a conspicuous artifact in the midst of wilderness. Built in 1970, the Hippo House was the vantage point, the antigo miradouro, from which well-heeled tourists, cool drinks in hand, watched wildlife herds as they grazed over the vast floodplain grassland below. Today the herds are back, but the house is a seldom-visited ruin. During the Mozambique civil war, almost all the buildings of Gorongosa National Park were torn down or blown away, leaving behind a few remnants scarred by bullets. The house had been reduced to a shell of its original self.

When I first visited the Hippo House, Mozambique was in the middle of the winter dry season. Other than along the watercourses, the vegetation of Gorongosa was brown and withdrawn. Insect life was still abundant, but harder to locate. I had been told that spiders, big ones, were abundant at the house, but I was quite unprepared for what I found. The interior of the ruined building was powder dry. Its floor, stanchions, and ceiling were windblown and coated with dust. No vegetation reached in from the outside, and except for a few small geckos resting on the pillars, there was no immediate sign of life of any kind. Instead, torn webs and long single threads of silk dangled from the ceiling like ghostly decorations in a haunted house. They swung gently back and forth in the occasional light breeze. No other movement or sound came from the seemingly empty space.

An unlucky katydid that flew into a web under the Hippo House is immediately killed and wrapped in silk by a female orb weaver.

An unlucky katydid that flew into a web under the Hippo House is immediately killed and wrapped in silk by a female orb weaver.

Where were the spiders I expected? Not one could be seen. But I knew they must be there someplace, alive, perhaps watching us. The idea of a hidden arachnid horde ready to rush out made me uneasy. Soon I saw something else: round objects plastered onto the ceiling. They were dusty and silent. My companions and I picked up a stick lying on the ground outside that was long enough to reach the ceiling, and tore two of the pouches apart. They proved to be silken egg pouches, undoubtedly made by spiders but now dry and empty; we were obviously not in the breeding season. The spiders themselves stayed hidden. Where were they? I grew more apprehensive.

We saw other, much larger, oblong pouches scattered over the rough eroded ceiling. At the tip of each was a circular entrance opening to a hollow interior. Using a flashlight and looking straight down the chamber, we could see what lay within. There at the rear of each pouch crouched a large spider, facing outward, its fangs, eyes, and the front of its tightly bunched legs visible. I wanted to see a specimen well enough to identify it, but hesitated. I was, to be frank, afraid of these crouched and waiting spiders. I suffer from mild arachnophobia. This spooky place was the setting of an arachnophobe’s nightmare.

The golden orb-weaver (Nephila senegalensis) is one of the largest spiders of Gorongosa. Its name comes from the beautifully golden coloration of its silk.

The golden orb-weaver (Nephila senegalensis) is one of the largest spiders of Gorongosa. Its name comes from the beautifully golden coloration of its silk.

We selected one of the pouches and poked at it in and out, but the spider stayed tight inside. One of my companions then took charge. He tore open the pouch and shook the inhabitant out into a transparent plastic bag. At last I could see what had lain within. The spider was heavy-bodied, the size of a thimble. When it suddenly spread its spiny legs, its width almost tripled.

I had solved the mystery of the spider house, at least in theory. The creatures in the silken bags were orb weavers, members of the spider family Nephilidae, called golden orb weavers, and, I later learned from an arachnologist, the species is Nephilengys cruentata. Some species of nephilids and the closely related araneids hide in retreats next to their webs; others remain in the centers of the webs. But how could there be so many spiders of this one species crowded together? Why are there no other creatures of any kind? The explanation I believed to be immediately clear. The floor of the lower level of the spider house is a layer of concrete. The interior is abnormally dry. Because the lower level cannot be invaded by any vegetation, few if any other forms of insect or arachnid life can live there. Yet flying insects undoubtedly fly through the wide-open space of the lower level, in through one side and out the other. A few might settle there to rest. The fate of most or all is the same: spider food.

Orb weaver (Nephilengys cruentata) from the Hippo House.

Orb weaver (Nephilengys cruentata) from the Hippo House.

My imagination was roused by this bizarre little world, but more so by my own reaction to it. When I took the captured spider back to Chitengo Camp, I found I was unable to make a specimen of it. That would mean fishing the monster out of the cellophane bag and working it into a bottle of preservative. So I simply opened the rear window of my room and dumped my captive live onto the ground below, where it would at least have a chance of making its way to a tree or building and spinning a new silken retreat.

I remember vividly the incident that made me an arachnophobe. I was eight years old. It was late summer, and I was exploring a vacant lot near our house. There were several full-grown female orb-weaving spiders in the high weeds, likely the common garden spider (Araneus diadematus), sitting in the center of their webs. I could not resist getting close enough to see all the details of one spider’s body. When I was about a foot away, it began to jerk back and forth in a menacing manner. I thought it was preparing to jump out and onto me. I ran. If that were not bad enough, I soon afterward saw a movie, the name of which I have long forgotten, in which a man is trapped in a cave. Blundering around, he becomes tangled in spiderwebs that are hung all around. Spiders, really big ones, climb down toward him, and . . .

Aversions and phobias of this kind, with the latter an extreme response causing panic and cold sweats, can be imprinted with as little as a single brief episode. They are rarely caused by a frightening experience with a knife, a gun, an automobile, or any other modern contrivance that can injure or kill. On the other hand, they easily and quickly follow a frightening experience with one of mankind’s ancient perils: snakes, spiders, wolves, heights, running water, and closed spaces. During millions of years of human prehistory, it has paid in a major Darwinian way to have quick, decisive response to the things that can kill you.

So I have forgiven myself for the wavelet of fear and revulsion I felt about the harmless denizens of the spider house. Let me make further amends by stressing that people are mostly safe amid what remains of living nature. We conquered the man-eaters long ago by destroying almost all of the big predators willing and able to hunt humans. They survive in our stories and in our legends of monsters. We imagine them silently emerging from caves and swamps, easing up from unexplored depths of the sea, or drifting down unseen from above. Walk into or swim in any wild habitat remaining on Earth, maintain the same level of caution you would on a city street, and you will be far safer than in most urban environments. Use common sense: don’t swim with crocodiles; don’t paddleboard among seals where great white sharks have been seen; and above all, never, ever run up to a mother grizzly bear with cubs to take a better look. Your greatest risk in the wild is from insect-borne disease—malaria, dengue, leishmaniasis, yellow fever—and these can be deadly if untreated. But they are transmitted chiefly among people. They can be easily avoided, and in any case pose less risk to you than the mélange of pathogens passing directly from person to person in human settlements.

The scary but harmless spiders in the Hippo House, and all the other animal species of wild environments like those of Gorongosa, are instinct-guided. They rigidly follow life-and-death routines formed during millions of years of evolution. Their lives are finely tuned and fragile in ways that are blessedly unthreatening to human beings.

Text Copyright © 2014 by Edward O. Wilson, Photographs Copyright © 2014 Piotr Naskrecki

Read more about the biological complexity and restoration of the fascinating ecosystem of Gorongosa National Park in “A Window on Eternity”, a new book by E.O. Wilson, with photos by P. Naskrecki (Simon & Schuster 2014).

Tarantulas, known in southern Africa as baboon spiders, may look frightening but are generally harmless. Their main line of defense is not their venom, but tiny urticating hairs that cover the entire body.

Tarantulas, known in southern Africa as baboon spiders, may look frightening but are generally harmless. Their main line of defense is not their venom, but tiny urticating hairs that cover the entire body.

Piotr Naskrecki and Edward O. Wilson in Gorongosa National Park, Mozambique.

Piotr Naskrecki and Edward O. Wilson in Gorongosa National Park, Mozambique.

 

Mozambique Diary: A single breath that changed the planet

The sound of an early ancestor of this lungfish (Protopterus annectens) taking it first gulp of air signified a pivotal moment in the history of life on Earth. The emergence of this behavior, along with the development of four limbs, set the stage for the conquest of terrestrial habitats by vertebrates, and the evolution of all tetrapods.

The sound of an early ancestor of this lungfish (Protopterus annectens) taking its first gulp of air signified a pivotal moment in the history of life on Earth. The emergence of this behavior, along with the development of four limbs, set the stage for the conquest of terrestrial habitats by vertebrates, and the evolution of all tetrapods.

About 400 million years ago, in the Devonian, in what was likely a shallow, freshwater pond in some tropical part of the world, a fish made a sound that started a dramatic chain of events, one that culminated in you and me being born. The sound was that of air being sucked in, as the fish lifted its mouth above the surface of the water, desperate to replenish falling oxygen levels in its bloodstream. Soon, gulping for fresh air became a necessity, as the gills failed to supply enough oxygen from the warm, muddy waters to sustain the animal’s activity. Its bladder, which up to that point helped maintain buoyancy for swimming, started to function as a gas exchange organ, an early version of lungs. At the same time, the fish’s pelvic and pectoral fins grew sturdier, and their connection to the rest of the skeleton more capable of lifting the body above the substrate. With these two steps the stage for the vertebrate conquest of land was set. We probably will never know when and where exactly this momentous transition took place, but we are pretty sure of what that fish looked like. And I am staring at it right now, as it looks back at me from the bottom of my beer cooler.

The Southern African lungfish (Protopterus annectens brieni)

The Southern African lungfish (Protopterus annectens)

Ever since I first set foot in Gorongosa National Park in Mozambique I have been obsessed with meeting my oldest living vertebrate cousin, the lungfish (Protopterus annectens). Despite its unassuming physique, reminiscent of a large eel, the lungfish holds a special place in the history of life on Earth. Biologists have always suspected that the lungfish gave us insight into the origin of terrestrial vertebrates, but only last year a massive molecular phylogenetic analysis (pdf) , based on 251 (!) genes, proved that the lungfish is a sister taxon to all tetrapods – amphibians, reptiles, birds, and you, and the rest of mammals. Previously that place was reserved for the coelacanth, a marine fish of equally ancient provenance, but now it appears that the coelacanth is an earlier offshoot of fishes that went its own, equally interesting, if less pivotal, way.

My first encounter with the lungfish took place a couple of months ago, when I ran across a fisherman who had caught a couple of these animals. Alas, by the time I met him they had been killed and gutted, leaving me heartbroken and even more obsessed. This time I made it abundantly clear to anybody who would listen that I wanted a live lungfish, and last week a fisherman from the village of Vinho finally delivered one into my hands.

In Gorongosa National Park lungfish are common, if rarely seen, inhabitants of seasonal water pans. During the dry season, when the pans evaporate, the lungfish burry themselves in the mud and estivate for several months. During this period their metabolic rates drop by about 60% and gas exchange is done entirely through their lungs.

In Gorongosa National Park lungfish are common, if rarely seen, inhabitants of seasonal water pans. During the dry season, when the pans evaporate, the lungfish burry themselves in the mud and estivate for several months. During this period their metabolic rates drop by about 60% and gas exchange is done entirely through their lungs.

It is difficult to describe the nearly religious reverence I felt when I saw my first live lungfish. Here was an animal that, I am pretty sure, looked like something I would see in the ponds of the early Paleozoic, long before first amphibians, even longer before dinosaurs. As I watched the lungfish slowly moving in my cooler, it suddenly lifted its head above the water and loudly inhaled a big gulp of air. I don’t think I will ever be able to forget the sound of it.

The lungfish does not have fins like other fishes. Rather, it has two pairs of whip-like appendages that act as weak, but very much functional legs. In 2011 an interesting experimental study (pdf) demonstrated that the pelvic fins are used by the lungfish in a fashion very similar to that of the land animals’ hind legs, for both walking and bounding. This in turn casts a new light on some early Devonian fossil tracks that were thought to have been left by primitive amphibians – in fact, they probably are those of semi-terrestrial lungfish ancestors. The development of articulated limbs with fingers (digited limbs) no longer seems to be the prerequisite to the conquest of land.

If you think that this looks like walking that’s because it is. Lungfish use their pelvic fins in a way very similar to that of a tetrapod’s legs – the distal part of the fin becomes a “foot” and the fins produce both walking and bounding motions.

If you think that this looks like walking that’s because it is. Lungfish use their pelvic fins in a way very similar to that of a tetrapod’s legs – the distal part of the fin becomes a “foot” and the fins produce both walking and bounding motions.

The more we study the lungfish the more fascinating it becomes. It is now clear that this animal holds the secret to the development of tetrapod ears, and they were the first to develop enameled teeth, the kind we, mammals now have. The lungfish is also superbly adapted to the harsh seasons of the southern African savanna, and can burry itself in the ground and survive for months out of water, hidden from the hot sun in a muddy cocoon (stories abound about African farmers digging out live, large fish from their dry fields.) Its dependence on atmospheric oxygen is so strong that the lungfish will drown if not allowed to breathe above the surface of the water. Its strongly reduced gills are virtually non-functional, but during the lungfish’s larval development are external and feathery, resembling those of the salamander larvae.

A portrait of the Southern African lungfish (Protopterus annectens brieni) from Gorongosa.

A portrait of the Southern African lungfish (Protopterus annectens) from Gorongosa.

In Gorongosa lungfish are common in seasonal pans and rivers of the park, feeding on a wide range of aquatic invertebrates, smaller fish, and frogs. As they are highly territorial, it is likely that almost every body of water on the plains has at least one of these remarkable animal. It is a shame that they are never seen by the visitors to the park – in my opinion the lungfish surpasses in its importance and a fantastical set of features any other vertebrate of Gorongosa, lions and elephants included, and I vow to make it my mission to spread the knowledge of its existence.

Last week, on March 27th, the E.O. Wilson Biodiversity Laboratory was officially opened, a culmination of my and many other people’s dream. More about the Laboratory soon, but I thought it fitting that the first vertebrate sample for our synoptic collection is a small snippet of the lungfish’s caudal fin, preserved for future DNA barcoding. The animal itself is being released back into its habitat, and I hope that this was not the last time that I looked into the eyes of my grand…grandfather’s twin brother.

Resembling an oversized salamander, the lungfish has four distinct limbs, a long tail, and only remnants of gills. The gills are virtually non-functional and the fish will drown if not allowed to breathe above the surface of the water.

Resembling an oversized salamander, the lungfish has four distinct limbs, a long tail, and only remnants of gills. The gills are virtually non-functional and the fish will drown if not allowed to breathe above the surface of the water.

Mozambique Diary: Sibylla

A portrait of the Precious Sibyl mantis (Sibylla pretiosa) – it is easy to get the impression that this insect really thinks.

A portrait of the Precious Sibyl mantis (Sibylla pretiosa) – it is easy to get the impression that this insect really thinks.

These days, if God speaks directly to you, be it about the precise date for the end of the world or his opinion about somebody else’s sexual preferences, you are either a crazy nut or a Westboro Baptist crazier nut. Ancient Greeks, clearly more open minded about such things, referred to a woman with powers to prophesy God’s actions with a much nicer-sounding honorific – Sibyl. Perhaps the 19th century Swedish entomologist C. Stål saw some of that craziness in the facial features of a gracile praying mantis from southern Africa, and christened it Sibylla pretiosa – the Precious Sibyl. Looking at this remarkably anthropomorphic insect it is indeed easy to get the impression that some strange thoughts are percolating in its brain.

The Precious Sibyl mantids (Sibylla pretiosa) are usually found high on the branches of savanna trees.

The Precious Sibyl mantids (Sibylla pretiosa) are usually found high on the branches of savanna trees.

I first encountered Sibylla many years ago in Zimbabwe, amazed at the sight of large mantids, nearly ghost-like in their slender built and pale coloration, that were zipping up and down smooth tree trunks. Last year I once again found Sibylla while collecting insects high in the canopy of a large Combretum tree in Gorongosa National Park. Alas, it was a tiny nymph. This month, however, while in Gorongosa during the peak of the rainy season, Sibyllas were plentiful on tree trunks and at the lights of the Chitengo Camp.

A male Sibylla cleaning his antennae.

A male Sibylla cleaning his antennae.

Despite their fragile appearance, these insects are skilled hunters, capable of catching and devouring prey at least half as long and nearly as heavy as themselves. They slowly stalk crickets and moths found on the bark, constantly vibrating their antennae in a fashion similar to that in many parasitoid wasps, which may indicate the use of chemical signals in detection of their prey. I have also seen these mantids feeding at night, which further supports the possibility of using non-visual cues while hunting.

Young Sibylla are very spindly looking and are found usually on leaves and tips of thin branches.

Young Sibylla are very spindly looking and are found usually on leaves and tips of thin branches.

Although superficially similar to empusid mantids, Sibylla is more closely related to another amazing dead leaf mimic, the Ghost mantis (Phyllocrania paradoxa), which I yet need to find in Gorongosa (but I was told by a resident that he had seen one). Most of the 14 known species of the genus Sibylla are found in West and Central Africa, and the individuals from Gorongosa are the first records of this genus of insects in Mozambique.

Sibylla mantids are closely related to the otherworldly Ghost mantids (Phyllocrania paradoxa). I have not yet found one in Gorongosa, but I am pretty sure that we have them there.

Sibylla mantids are closely related to the otherworldly Ghost mantids (Phyllocrania paradoxa). I have not yet found one in Gorongosa, but I am pretty sure that we have them there.

Alas, having caught quite a few individuals of Sibylla attracted to my mercury vapor lamp in Gorongosa, I am now convinced that this pretty insect does not have the powers to foretell the future. Otherwise they would have known that if you come to my light, you never leave.

Sibylla are voracious predators of insects found on tree bark and branches.

Sibylla mantids are voracious predators of insects found on tree bark and branches.