Archives

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 Other than along the watercourses, the vegetation of Gorongosa was brown and withdrawn.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.

 

Footprint Cave, Belize

Africa in Mesoamerica – a beautiful, little pool on the floor of the upper chamber of the Footprint Cave; it even has an adjoining pool that looks like the Arabian Peninsula.

Africa in Mesoamerica – a beautiful, little pool on the floor of the upper chamber of the Footprint Cave; it even has an adjoining pool that looks like the Arabian Peninsula.

It has been a long while since the last update to this blog, mostly because of my hectic travel schedule (in fact, I am typing this on a shaky train ride). But it has been an interesting time, with lots of great photo ops. Last week I joined Alex Wild, John Abbott and Thomas Shahan in Belize to teach BugShot 2013, an intense course in tropical insect macrophotography. Aside from working with a friendly group of photography masters and enthusiastic students it was my first exposure to some of the most interesting members of the troglobitic Mesoamerican fauna as the workshop was held at the Caves Branch Lodge in central Belize, an area famous for its karst formations, replete with deep limestone caves.

The most famous cave in the area is the Footprint Cave, named after calcified Mayan footprints found in the deeper section of the cave, along with a number of artifacts and skeletal remains. The cave was looted in 1994, and many artifacts and remains are now gone, but you can still see there ancient fire places and shards of Mayan pottery. It was quite an unreal and humbling experience to sit next to a pile of ash that might be over 2,000 years old but still looks warm. The cave itself is stunningly beautiful, cathedral-like, with massive stalactites that shimmer in the light of the headlamp. The shallow Caves Branch River flows through it, and as you walk along its bed large catfish and shrimp follow your every step, looking for small aquatic invertebrates flushed from under the sand.

Female cave cricket Mayagryllus apterus, a species endemic to the Caves Branch system of Belize.

Female cave cricket Mayagryllus apterus, a species endemic to the Caves Branch system of Belize.

As we walked deeper into the cave, leaving behind its large opening and eventually all traces of natural light, we began to discover a multitude of life forms that call this cave their home. Biologists explored Footprint Cave in early 1970’s, but little work has been done since. Many animal species found in the Caves Branch system are likely endemic, and some still await their formal scientific description. I was thrilled to see dozens of long-legged cave crickets Mayagryllus apterus, described only in 1993 from specimens collected in these caves. They were often accompanied by large, equally spindly amblypygids Paraphrynus raptator (Phrynidae), and apparently another, yet undescribed species of the family Charontidae is also present in the cave (and Gil Wizen might have found a third, possibly new amblypygid species). I was hoping to find some dinospiders (Ricinulei) there, alas, no such luck, but flipping rocks on the banks of Caves Branch River revealed a tiny, equally interesting arachnid, a pygmy vinegaroon (Schizomida). The species found in the Footprint Caves is a yet undescribed species of Schizomus, and I would love to be able to collect some specimens and describe them (I need to look into getting some permits for Belize).

A troglobitic isopod crustacean Troglophiloscia sp.; note its lack of pigmentation and eyes, characteristics typical of cave-dwelling organisms.

A troglobitic isopod crustacean Troglophiloscia sp.; note its lack of pigmentation and eyes, characteristics typical of cave-dwelling organisms.

Silk strands on the cave ceiling, produced by the larvae of predaceous fungus gnats (Keroplatidae: ?Macrocera sp.)

Silk strands on the cave ceiling, produced by the larvae of predaceous fungus gnats (Keroplatidae: ?Macrocera sp.)

Yet the most interesting organism in the cave was a fly. When we shone the light at the low celling of the cave we could see curtains of thin, glistening strands of sticky silk produced by larvae of predaceous fungus gnats of the family Keroplatidae; I have not been able to identify the species that lives in the Footprint Cave, but it is possibly a member of the genus Macrocera (Macrocerinae). The strands spun by the larvae are covered with droplets of oxalic acid, which trap and kill tiny flying insects, mayflies mostly, found in the cave. Members of a related subfamily Arachnocampinae found in Australia and New Zealand are famous for their bioluminescence, but the ones found in Belize are of the non-glowing variety. Still, it was a beautiful spectacle to see thousands of hair-like strands undulate gently in the breeze caused by a person walking several meters away.

The strands are covered with droplets of oxalic acid, which trap and kill unlucky insects, such as this mayfly, that brush against them in flight.

The strands are covered with droplets of oxalic acid, which trap and kill unlucky insects, such as this mayfly, that brush against them in flight.

Everybody was sad to leave the cave, which turned out to be the highlight of our photographic workshop, although the fauna of the rainforest that surrounded the lodge where we stayed was equally interesting. Not being able to collect anything was torture for me, but I hope that some day soon I will be able to come back to Caves Branch, this time wearing only my entomologist’s hat.

A new, yet unnamed species of the pygmy vinegaroon (Schizomus sp.) from the Footprint Cave.

A new, yet unnamed species of the pygmy vinegaroon (Schizomus sp.) from the Footprint Cave.

New life

The Transkei shieldback (Transkeidectes multidentis, 1992) was one of the first species that I described, based on a single specimen collected in 1947 near Port St. John's in the Eastern Cape of South Africa. Describing a new species based on a single specimen is a horrible idea (you never know whether you might be dealing with an aberrant form of something already known), and ever since I have been looking for more individuals to confirm the existence of this species.

The Transkei shieldback (Transkeidectes multidentis, 1992) was one of the first species that I described, based on a single specimen collected in 1947 near Port St. John’s in the Eastern Cape of South Africa. Describing a new species based on a single specimen is a horrible idea (you never know whether you might be dealing with an aberrant form of something already known), and ever since I have been looking for more individuals to confirm the existence of this species.

To my enormous relief, I have recently located a thriving population of the Transkei shieldback in the coastal forest of the Silaka Nature Reserve near Port St. John's. The species is real.

To my enormous relief, I have recently located a thriving population of the Transkei shieldback in the coastal forest of the Silaka Nature Reserve near Port St. John’s. The species is real.

Today marks the first anniversary of The Smaller Majority blog which, to my delight and surprise, has been steadily gaining readership. I am grateful to all who visited these pages over the last 12 months, especially those who kindly left the wonderful, insightful, occasionally snarky comments under many of the 130+ individual stories – keep’em coming! So far this blog has amounted to 75,000 words and 770 photos – that’s a decent size book; maybe I should have done that instead? Nah! And what better way to acknowledge the portent of this occasion than to talk about what I consider the most exciting aspect of my work as an entomologist – the discovery of new forms of life.

When I was about seven years old my father said something that, in retrospect, was probably the most important piece of information I have ever received, one that has influenced my entire life. I should mention that my father was an astronomer, and he did his best to try to entice me with his line of work, to no avail. (At some point he even built a telescope for me, but I only used it to watch birds and spy on my neighbors; I was a lost cause.) To my question about a possibility of finding life elsewhere in the Universe he replied that those chances were slim, but that our own planet still had many organisms that remained undiscovered and unnamed. That statement stopped me in my tracks. I instantly envisioned mysterious, dinosaur-like creatures hiding in the depths of African jungles. But he explained that the yet-unnamed animals were probably small, and that they might even be living in our own backyard. I am certain that at that very moment I decided to become an explorer who would spend his life questing for those elusive, undiscovered creatures. Of course, I did not realize then that most discoveries of new species take place among dusty drawers of museums, made by taxonomists whose lives are decidedly less than glamorous. But the stage for a career in entomology was set.

The Martian landscapes of the Northern Cape of South Africa, despite its foreboding appearance and extremely harsh conditions, is home to a number of very interesting orthopteroid insects.

The Martian landscapes of the Northern Cape of South Africa, despite their foreboding appearance and extremely harsh conditions, are home to a number of very interesting orthopteroid insects.

My friend Corey Bazelet and I discovered the handsome, wingless katydid Brinckiella arboricola Naskrecki & Bazelet, 2009 in the Geogap Nature Reserve of Northern Cape.

My friend Corey Bazelet and I discovered the handsome, wingless katydid Brinckiella arboricola Naskrecki & Bazelet, 2009 in the Geogap Nature Reserve of Northern Cape.

It took me fifteen years to run into a beautiful little gem of a katydid in a meadow in Turkey, an animal that until then had eluded entomologists. I named it Poecilimon marmaraensis, after the Marmara Sea on the shores of which this species occurs. The elation of knowing that I was the first person on Earth to find it was intoxicating. I am sure that all my fellow taxonomists have felt it at some point in their lives, and for many it is the ultimate reward. Finding new forms of life is to me one of the greatest adventures in biology, one that the current biodiversity crisis makes a pressing necessity. Extinctions and the appearance of new species are natural phenomena that once were fairly well balanced, with speciation always slightly outpacing extinction and making Earth’s biodiversity increasingly richer. But with the advent of man, this balance started to tip dramatically toward extinction, and we now lose species at a rate a thousand times higher than the natural, “background” one. Regardless of being named or not, each species gone extinct is another book of genetic code burned, another piece of the intricate puzzle of life on Earth irreversibly lost. And while destruction of natural habitats and the alarming pace of species loss give little hope for preserving all the components of Earth’s biota for future generations, we should make every effort to document all organisms that still inhabit our planet. Still, on some days, the nagging pessimist in me points out that maybe all that we taxonomists do is carve names on tombstones and write obituaries for species who may be gone by the time their formal, scientific names are published. He may be right, but I hope he isn’t.

In spite of all the evidence that the world at large simply does not care about most of our non-human brethren, I still believe that armed with the complete knowledge of all Life on Earth we will be able to make the best decisions as to where conservation efforts should be focused, and that we will manage to save a very high proportion of the world’s phyletic diversity and biocomplexity. The more diverse Life is, the more stable and capable of self-regulation are its assemblages. The more species alive, the more likely we are to discover new medicines, new crops, or new structures worth imitating. The more Life we have around, the more our own is worth living.

Brown-faced spear bearer (Copiphora hastata Naskrecki, 2000) – This huge conehead katydid is common across Central America. Females of this and related species carry an enormous ovipositor that allows them to lay eggs at the base of litter-filled fronds of small palm trees.

Brown-faced spear bearer (Copiphora hastata Naskrecki, 2000) – This huge conehead katydid is common across Central America. Females of this and related species carry an enormous ovipositor that allows them to lay eggs at the base of litter-filled fronds of small palm trees.

The Costa Rican rainforest is home to about 350 species of katydids, many yet unknown, of which I have so far discovered and named a little over 50.

The Costa Rican rainforest is home to about 350 species of katydids, many yet unknown, of which I have so far discovered and named a little over 50.

The Simandou Mts. blattodean (Simanoda conserfariam Roth & Naskrecki, 2003) is an insect that may be already extinct in the wild. I first found it in a cave in SE Guinea (West Africa), a place that was part of a large mining concession. Although mining operations in the Simandou were recently halted (presumably soon to be resumed), the cave was on the path of a major road that was being constructed and it may no longer exist.

The Simandou Mts. blattodean (Simanoda conserfariam Roth & Naskrecki, 2003) is an insect that may be already extinct in the wild. I first found it in a cave in SE Guinea (West Africa), a place that was part of a large mining concession. Although mining operations in the Simandou were recently halted (presumably soon to be resumed), the cave was on the path of a major road that was being constructed and it may no longer exist.

I described the Agile grasshopper (Rhachitopis brachyopterus Naskrecki, 1992) based on a small series of preserved specimens collected in Zimbabwe, but until recently have not seen a live individual. This is very common in entomology as most species are described using specimens from museum collections, often collected tens or even over a hundred years earlier.

I described the Agile grasshopper (Rhachitopis brachypterus Naskrecki, 1992) based on a small series of preserved specimens collected in Zimbabwe, but until recently have not seen a live individual. Such a situation is very common in entomology as most species are described using specimens from museum collections, often preserved tens or even over a hundred years earlier.

During the Cheringoma Plateou biodiversity survey in Gorongosa National Park, Mozambique, I crawled out of my tent one morning and the first insect I saw was my Agile grasshopper. Little compares to the joy of seeing for the first time a living individual of a species that you have described and named.

During the Cheringoma Plateau biodiversity survey in Gorongosa National Park, Mozambique, I crawled out of my tent one morning and the first insect I saw was my Agile grasshopper. Little compares to the joy of seeing for the first time a living individual of a species that you have described and named.

In addition to my work on insects, I have occasionally dabbled in arachnids. The Atewa dinospider (Ricinoides atewa Naskrecki, 2008) was an exciting discovery I made in SE Ghana.

In addition to my work on insects, I have occasionally dabbled in arachnids. The Atewa dinospider (Ricinoides atewa Naskrecki, 2008) was an exciting discovery I made in SE Ghana.

When it comes to yet undiscovered and unnamed species, Papua New Guinea is one of the richest places on the planet – nearly 80% of all species that I had collected there turned out to be new to science. One of the new species was the Ingrisch's katydid (Ingrischia macrocephala Naskrecki & Rentz, 2010), which my co-author David Rentz aptly christened "a katydid designed by a committee."

When it comes to yet undiscovered and unnamed species, Papua New Guinea is one of the richest places on the planet – nearly 80% of all species that I had collected there turned out to be new to science. One of them was the Ingrisch’s katydid (Ingrischia macrocephala Naskrecki & Rentz, 2010), which my co-author David Rentz aptly christened “a katydid designed by committee.”