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Lungless and happy about it

It is rather amazing that a terrestrial animal as big as this Ringtail salamander (Bolitoglossa robusta) from Costa Rica can spend its entire life without taking a single breath and rely entirely on gas exchange through its skin.

It is rather amazing that a terrestrial animal as big as this Ringtail salamander (Bolitoglossa robusta) from Costa Rica can spend its entire life without taking a single breath and instead relies entirely on gas exchange through its skin.

Of all the organs in my body, the one that I would be most reluctant to part with (perhaps with the exception of my eyes) are the lungs. It seems that we need them more than anything else. True, we need all the other bits, but lungs seem particularly useful. Without them the brain stops working in a matter of minutes, the vascular system loses its main reason to exist, and the biochemical processes in pretty much every cell come to a grinding halt. Like the hideous inflatable Santa in front of my neighbor’s house, the complex edifice of the human body would immediately collapse if the air supply were to be shut off. It seems that if you are a land-dwelling vertebrate you better have lungs, or you are not going to last very long. And yet, defying common sense, there is a group of terrestrial animals that got rid of their lungs altogether, and in doing so have become widely successful, outcompeting their lunged relatives in both the number of species and their collective biomass. They are the lungless salamanders of the family Plethodontidae.

The Redback salamander (Plethodon cinereus), a small, unassuming animal common in the eastern United States, is a marvel of evolution, with physiology that makes our own appear laughably inefficient.

The Redback salamander (Plethodon cinereus), a small, unassuming animal, common in the eastern United States, is a marvel of evolution, with physiology that makes our own appears laughably inefficient.

I thought of them last month, when freakishly warm weather in Boston forced me to clean up the accumulation of dog poop from the front lawn, which in any other year the snow would have mercifully covered up until spring. The unseasonal warmth also woke up a multitude of creatures that should have been fast asleep, including a couple of Redback salamanders (Plethodon cinereus), which I found under a wooden plank in the garden. Despite the ice crystals glistening in the half-frozen soil, they were surprisingly agile. “Agile” is of course a relative term, especially when talking about an animal whose metabolism is entirely dependent on oxygen passively permeating the skin. Nearly 100% of the oxygen intake and excretion of the carbon dioxide takes place on the surface of the skin of these salamanders, with the throat (buccopahryngeal cavity) accounting for an additional, small proportion of the gas exchange (perhaps for this reason lungless salamanders still retain well-developed nostrils.) Clearly, animals that are incapable of taking active breaths, and thus accelerating or decelerating gas exchange at will, cannot be marathon runners, or runners of any kind. And somehow, by employing various degrees of toxicity and the ability to subsist on low-nutrition diet of springtails and mites, lungless salamanders have managed to become the dominant family of amphibians of the Western hemisphere. Nearly 400 species have already been described and new ones are being discovered every year in both the cool, temperate forests of North America, and in the rainforest canopy of the Neotropics. In some places their numbers are staggering. A recent analysis of the population of the Southern Redneck salamander (P. serratus) of the Ozark Highlands in Missouri put their numbers at 1.88 billion (!) individuals, with the biomass equivalent to that of most whitetail deer in that region – that’s 1,400,000 kg (3,086,471 lb) of amphibian flesh.

Among many adaptations to the arboreal lifestyle are the lungless salamanders' pad-like feet. Despite of the overall similarity, this foot shape has evolved independently in different species of the genus Bolitoglossa.

Among many adaptations to the arboreal lifestyle are the lungless salamanders’ pad-like feet. Despite the overall similarity, this foot shape has evolved independently in different species of the genus Bolitoglossa.

Although all members of the family Plethodontidae are entirely lungless, their ancestors were not. What prompted the loss is still a mystery, and two competing theories, neither particularly compelling, try to explain it. According to the older of the two, lungless salamanders originated from a lineage that inhabited cold, fast flowing and well-oxygenated streams of the Cretaceous Appalachia (lungless salamanders still dominate the amphibian fauna of that region). The loss of lungs made them less buoyant and thus more capable of maintaining their position at the bottom of the stream while hunting for prey. But some researchers pointed out the lack of geological evidence for cold, upland environments in the Mesozoic Appalachia. Instead, they argue, lungless salamanders come from oxygen-poor tropical waters, where highly humid terrestrial environment proved to be a better alternative. Once on land, dense vegetation exerted adaptive pressure to evolve small, narrow heads, which in turn prevented the animals from filling their lungs effectively, and leading to the reliance on respiration through the skin. If this sounds sketchy to you, you are not alone. Most herpetologists today lean towards the first explanation, with the added argument that the loss of lungs happened early on in the larval development of the aquatic ancestors of the plethodontids. But the truth is, nobody really knows.

The ability to use a prehensile tail, a rarity in the animal kingdom, is one of the most amazing characteristics of the large, arboreal Ringtail salamander (Bolitoglossa robusta) from Costa Rica.

The ability to use a prehensile tail, a rarity in the animal kingdom, is one of the most amazing characteristics of the large, arboreal Ringtail salamander (Bolitoglossa robusta) from Costa Rica.

What is not in question is the fact that lungless salamanders rule the forests of North, Central, and parts of South America. Larger species tend to be ground-dwelling, whereas smaller ones live high in the canopy. The arboreal salamanders have evolved a number of cool adaptations to such a lifestyle. The Central American genus Bolitoglossa is famous for its lack of distinct fingers. Instead, these salamanders have pad-like feet that help them move on smooth, wet surfaces of rainforest trees. And although feet in all species of Bolitoglossa look similar, they are the result of two very different evolutionary processes. In smaller species, such as the colorful (and toxic) B. mexicana, the digit-less foot is the result of paedomorphosis – a developmental mechanism during which juvenile characters are retained in adult, reproductive animals. In other words, they have baby feet, and they rely on simple surface adhesion to cling to leaves and branches.

Larger species, such as the Costa Rican B. robusta, also have pad-like feet, but underneath the webbing sit fully developed digits and a complex musculature. The central part of the foot can be lifted, thus creating suction, a mechanism similar to that used by marine cephalopods. But wait, there is more. In addition to having suction cups for feet, this salamander has a prehensile, chameleon-like tail, which it uses to save itself from falling off trees. When I first saw one of these animals a few years ago pull this trick high in the branches in Tapanti National Park, I thought I was hallucinating. And the similarity to chameleons does not end there – just like those reptiles, lungless salamanders sport a long, projectile tongue (in one species the tongue is 80% as long as the body, and salamanders are pretty long animals!) They can eject it with an amazing speed, a mere 117 ms, to catch fast moving prey. And this ballistic tongue projection is an order of magnitude more powerful than that of any muscle in any other living vertebrate species.

All this to say that the next time you find a small, curled up salamander under a rock, look at it with a little more respect. This ancient animal can pull off tricks that would put many Marvel Comics characters to shame. Without taking a breath. Ever.

Ringtail salamander (Bolitoglossa robusta) on a tree branch in Tapanti National Park, Costa Rica.

Ringtail salamander (Bolitoglossa robusta) on a tree branch in Tapanti National Park, Costa Rica.

A really cool sequence of a lungless salamander (Hydromantes) using its projectile tongue (BBC).

Ghost hunting

A silhouette of the first ghost mantis recorded from Gorongosa National Park in Mozambique.

A silhouette of the first ghost mantis (Phyllocrania paradoxa) recorded from Gorongosa National Park in Mozambique.

I have been working in Africa for quite a while and during this time I have seen my share of iconic animals that epitomize the awesome continent’s fauna. There are still, of course, many that I yet need to meet in person – aardvark, “hairy” Trichobatrachus frog, Acridoxena katydid, to name a few – but luck or stubbornness allowed me to witness others. Few things can match the elation of meeting the gaze of a foraging chimpanzee, discovering a toy-like primate poto in the forest canopy over my head, or running into a fight between a hyena and a leopard over a freshly killed kudu. But my first encounter with one of the less known species, the ghost mantis (Phyllocrania paradoxa), was at least as memorable.

A female ghost mantis (Phyllocrania paradoxa) – these insects are such superb mimimcs of dry vegetation that it is often difficult to tell which part belongs to the plant and which to the insect.

A female ghost mantis (Phyllocrania paradoxa) – these insects are such superb mimimcs of dry vegetation that it is often difficult to tell which part belongs to the plant and which to the insect.

It happened during my first trip to Zimbabwe, at the time when the tumor in Robert Mugabe’s brain was still semi-dormant and the country, “Africa’s bread basket”, was experiencing its first and only period of relative political freedom and economic prosperity. I was staying with a group of friends in the suburbs of the recently re-christened capital Harare, vaguely intrigued with, but blissfully ignorant of why so many houses were standing empty, their gauged windows bordered with the mascara of freshly extinguished flames. Africa was new to me, and I inhaled its intoxicating atmosphere and devoured the sights of alien landscapes and even more alien fauna. But I came prepared – for years before my first visit I had been voraciously reading all that I could find about insects and other members of Africa’s smaller majority. The ghost mantis was one of my most desired quarries and I started looking for it the moment I landed. Alas, a month on and with no trace of the animal, it was beginning to feel as if I were really hunting a ghost. I had spent countless hours sifting through the leaf litter, scanning bushes and trees, sweeping my net through all kinds of vegetation – nothing.

One day I stood on the platform of a railway station, waiting for a train to take me to Bulawayo. It was late October, the peak of the dry season, and shriveled leaves were falling from trees onto my head in a rare, merciful breeze. One, fairly large and twisted brown leaf landed on my shoulder. I tried to brush it off but it just sat there, trembling in the wind. I flicked it again. It landed lower on my sleeve. And then the leaf started to climb up my arm. I looked, still not believing. Could it be? No, this is just a piece of withered plant. But it was, finally, a ghost mantis.

Ghost mantids are extremely polymorphic in both their coloration and the shape of the strange processes on their heads.

No two individuals of ghost mantids are alike, which prevents their principal predators, birds and primates, from learning how to tell them apart from real leaves.

That was 25 years ago and it took me this long to run across another one. In fact, I had more run-ins with the notoriously elusive leopards than with this incredible insect. But this year, in April, I was finally able to confirm ghost mantids’ presence in Mozambique’s Gorongosa National Park (something that I have always suspected), when my friend, entomologist Marek Bakowski, found the first individual during our annual biodiversity survey. Since then I have encountered a few more ghost mantids in the park.

A Gorongosa ghost mantis with a freshly laid ootheca.

A Gorongosa ghost mantis with a freshly laid ootheca.

A molting ghost mantis.

A molting ghost mantis.

Thanks to their otherworldly appearance ghost mantids have long been the favorite of amateur insect collectors and, since they can be easily bred in captivity, they have recently become very popular in the pet trade. Now all you need to do to see a live ghost mantis is to pay a few bucks online and one will be delivered to your door. But for an animal so widely kept, shockingly little is known about its biology and behavior in its natural habitat. Nobody is even sure how many species of ghost mantids there are. Three species of the genus Phyllocrania have been described, only to be synonymized a few years ago. All three were recognized as separate species based on the differences in the shape of the leaf-like process on the head, which can vary wildly within the same population. Ghost mantids, like many other insects that rely on leaf-like camouflage, display an ungodly degree of polymorphism, and no two specimens are alike. But the species’ distribution, throughout sub-Saharan Africa and Madagascar, hints at the possibility of distinct, genetically isolated lineages.

Like most praying mantids, the ghost mantis is an ambush predator, a truly superb one. But unlike many others, it is not inclined to attack members of its own species, and I know of no case of the female devouring a male during copulation, as it is often the case in some other lineages of these insects. In Gorongosa ghost mantids are found mostly in the understory of miombo and mopane woodland, and the only time I witnessed one feeding, it was chomping on a grasshopper. Females produce strange, caterpillar-like oothecae, and newly hatched nymphs look and behave like black ants; after the first molt they turn into perfect replicas of dried-up chaff. How males and females find each other, however, is a mystery to me. It is likely that females, like in other highly cryptic mantids, produce sex pheromones to attract their mates.

Next on the list of African biodiversity icons to confirm in Gorongosa, the Devil mantis. I know you are there and I will find you.

No two individuals of ghost mantids are alike, which prevents their principal predators, birds and primates, from learning how to tell them apart from real leaves.

Ghost mantids are extremely polymorphic in both their coloration and the shape of the strange processes on their heads.

 

 

Mozambique Diary: Red-headed flies

Red-headed flies (Bromophila caffra) are striking and common animals in East and southern Africa, but little is known about their biology.

Red-headed flies (Bromophila caffra) are striking and common animals in East and southern Africa, but little is known about their biology.

Two months, that’s how long I have been neglecting this blog. Some people had even sent me messages to check if I were still alive. But I am alive and the reasons for my silence were good – until last week I was in Mozambique, working at the Wilson Lab and busily preparing for the next biodiversity survey of Gorongosa National Park. While there I had precious little time to write or take photos, but I did manage to take some shots of a few interesting critters. It is the rainy season in Gorongosa now and insect life is exploding. I had set up an ultraviolet light in front of my office to collect all members of my target groups (orthopteroid and dictyopteroid insects) and to cherry-pick the more interesting species from orders that we don’t yet collect systematically. On some nights the sheet was sagging under the weight of hundreds of species of insects and for a while mysterious redheads kept coming to the light.

Red-headed flies, which in Mozambique emerge at the end of the rainy season, like to hang in clusters on leaves.

Red-headed flies, which in Mozambique emerge at the end of the rainy season, like to hang in clusters on leaves.

I recognized them from my earlier trips to Gorongosa as Red-headed flies (Bromophila caffra) – large, slow moving insects, reluctant to take to the air, and much happier to hang in clusters from low tree branches. They are truly striking animals, showy and clearly unconcerned about attracting anybody’s attention, including that of potential predators. There were many birds and grabby vervet monkeys in the camp, who not so much as looked in the direction of the flies who slowly spun in clusters on leaves.

Adult Red-headed flies feed on dung and other decaying organic matter.

Adult Red-headed flies feed on dung and other decaying organic matter.

But for an insect as conspicuous and common as the Red-headed fly, shockingly little is known about its biology. In fact, the last scientific paper that mentions it by name (according to an extensive MetaLib cross-database search) is from 1915, and it does so only to compare the fly’s strikingly red head to another species. As already pointed out in an excellent post about this species by Ted C. MacRae, there exists only anecdotal evidence that the larvae of this species might be feeding on the roots of Terminalia trees, potentially sequestering toxic cyclic triterpenes, which would explain the adult flies’ aposematic coloration. But, as is the case with so many African invertebrates, nobody really knows.

There is also another possibility. One morning while in Gorongosa I woke up to find my arms covered with big, painful blisters. The night before I had spent a couple of hours searching for insects in tall grass and remembered seeing many contrastingly colored, red and black beetles of the genus Mylabris. “Oh, that’s why they are called blister beetles!”, it dawned on me, a little too late. While walking through the grass I must have brushed against some of these insects, and a mere touch against my skin caused the blisters, which lasted for over a week, to appear. The beetles themselves are highly toxic, deadly even, and no bird or other vertebrate will try to eat them. It is therefore quite possible that the flies are fakers – not toxic at all but simply counting on predators’ reluctance to try a potentially harmful meal. This phenomenon, known as Batesian mimicry, is common in the animal kingdom and I strongly suspect that the flies are an example of it.

I strongly suspect that Red-headed flies are Batesian mimics of blister beetles of the genus Mylabris. These beetles not only cause painful, long-lasting blisters but are also potentially deadly toxic.

I strongly suspect that Red-headed flies are Batesian mimics of blister beetles of the genus Mylabris. These beetles not only cause painful, long-lasting blisters but are also potentially deadly toxic.

When I return to Gorongosa next month the flies should still be around. It will also be the time when many young house geckos (Hemidactylus mabouia) are hanging around the lights of the camp, having hatched in January and February. It might be a bit evil on my part, but I think I will do some feeding experiments to see if the lizards, which at that point should still be naive about the flies, have any adverse reaction to eating them. Watch this space.

One peculiar morphological characteristic of the Red-headed flies is the absence of the ocelli, which are typically found on the head of other flies.

One peculiar morphological characteristic of the Red-headed flies is the absence of the ocelli, which are typically found on the head of other flies.

Dermatobia Redux

Raising two dipteran children was an interesting experience. It was embarrassing on a few occasions, when both of my arms started bleeding profusely in public; painful at times, to the point of waking me up in the middle of the night; and inconvenient during the last stages of the flies’ development, when I had to tape plastic containers to my arms to make sure that I will not lose the emerging larvae. But other than those minor discomforts it was really not a big deal. Perhaps my opinion would have been different had the bot flies decided to develop in my eyelids, but I actually grew to like my little guests, and watched their growth with the same mix of pleasure and apprehension as when I watch the development of any other interesting organism under my care.

Having two bot fly larvae embedded in my skin have also made me ponder once again the perplexing element of the human psyche that makes us abhor parasites but revere predators. Why is it that an animal that is actively trying to kill us, such as a lion, gets more respect than one that is only trying to nibble on us a little, without causing much harm? I strongly suspect that it has to do with our genetically encoded sense of “fairness” – we perceive parasites as sneaky and underhanded, whereas predators attack us head-on and thus expose themselves to our retaliation. They are brave, or so we think. This, of course, is a very naive and anthropomorphic interpretation of nature. A lion is no “braver” than a bot fly, who has to skillfully hunt mosquitos to assure the dispersal of her eggs and risk more dangers than a lion, a top predator with no natural enemies. Most importantly, to a bot fly we, humans, are a renewable resource – it is in the bot fly’s best interest that we live a very long life and thus can be “reused” – hence the minimum amount of suffering that this species causes. To a lion we are nothing more than a one-time meal. But we should not judge either species for their actions – there is no “good” or “bad” in nature – nature is amoral.

I am saying this to prepare you for a short video that I have made about my experience of raising a bot fly. I don’t want you to think that it is “creepy” or “weird”. It is simply a documentation of an interesting organism, who happens to develop in the skin of large mammals. But please be forewarned that this video includes a few sequences that some viewers may find disturbing. If you don’t want to have nightmares about things living inside you (which they already do, by the way), please don’t watch it. But if you are prepared to be open-minded and appreciate God’s wonderful creations in all their amazing glory, enjoy the show!

So long, 2014

It was an interesting, busy year, which explains in part why I have been neglecting this blog recently. I am not going to give a month-by-month account of 2014 but thought that a few highlights might be in order.

Early in the year I made a brief visit to Quirimbas National Park in northern Mozambique where I found Pardalota karschiana, one of the most remarkable and beautiful katydids in the world.

Early in the year I made a brief visit to Quirimbas National Park in northern Mozambique where I found Pardalota karschiana, one of the most remarkable and beautiful katydids in the world.

The most important event of 2014 for me was, unquestionably, the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa. This facility, which I now direct, is quickly becoming a hub of renewed scientific and educational activity in Mozambique. Here our technician Ricardo Guta teaching kids from nearby schools about insects of Gorongosa.

The most important event of 2014 for me was, unquestionably, the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa. This facility, which I now direct, is quickly becoming a hub of renewed scientific and educational activity in Mozambique. Here our technician Ricardo Guta is teaching kids from nearby schools about insects of Gorongosa.

I have my first encounter with the African lungfish. This animal appears to be more resourceful than I ever suspected. Here a PBS cameraman John Benam and producer James Byrne witness its amazing ability to escape.

I have my first encounter with the African lungfish. This animal appears to be more resourceful than I ever suspected. Here a PBS cameraman John Benam and producer James Byrne witness its amazing ability to escape.

In April E.O. Wilson and I published a book on the biodiversity of Gorongosa and the efforts to restore this unique place on Earth.

In April E.O. Wilson and I published “A Window on Eternity“, a book on the biodiversity of Gorongosa and the efforts to restore this unique place on Earth.

During a BugShot macrophotography workshop on Sapelo Island in Georgia I find my first zorapteran!

During a BugShot macrophotography workshop on Sapelo Island in Georgia I find my first zorapteran!

Back in Gorongosa, with the help our mammalogist Jen Guyton, I learn how to shoot bats in flight.

Back in Gorongosa, with the help of our mammalogist Jen Guyton, I learn how to shoot bats in flight.

A short trip to Belize in September gives me a chance to meet Uo, the mythical rain caller.

A short trip to Belize in September gives me a chance to meet Uo, the mythical rain caller.

A successful sting operation leads to the rescue of a pangolin and her baby from a poacher – I finally get to see and touch the animal I had been dreaming of seeing all my life.

A successful sting operation leads to the rescue of a pangolin and her baby from a poacher – I finally get to see and touch the animal I had been dreaming of seeing all my life.

The internets go batshit crazy over a single specimen of a common arthropod collected for scientific research.

The internets go batshit crazy over a single specimen of a common arthropod collected for scientific research.

That’s about it – I am looking forward to 2015, which promises to be even more exciting. Watch this space and thank you for reading!

What to do?

This morning, in my bathroom, I was faced with a dilemma.

Spider_in_sink

And here are the results of the poll on what I should do about this sticky situation. It is heartening to see that the majority of voters would release the spider (which is what I did), but also rather sad that over 38% of respondents (discounting the 5% who were high while voting) would resort to violence (against either me or the spider). Votes

Mozambique Diary: Webspinners

An adult female of a yet unidentified webspinner from Gorongosa National Park.

An adult female of a yet unidentified webspinner from Gorongosa National Park.

It has been a busy couple of months for me – first organizing a month-long biodiversity survey in Gorongosa National Park, then dealing with various aspects of our newly created E.O. Wilson Biodiversity Laboratory. But now that I am home I can process all the photos taken in Mozambique and, finally, write a few long overdue blog posts.

Our second biodiversity survey of the park started with a week of sampling in the Sand Forest, an interesting plant community near Chitengo, the park’s main camp. While somewhat underwhelming at first glance, this stunted forest that grows on remarkably infertile, pale and sandy soils, produced some of the finest discoveries of the survey. It was also an exciting place to be, on the account of roaming elephants (who really didn’t like people invading their private feeding ground) and a radio-collared male lion (who, I was told by our lion researcher Paola Bouley, might actually “like” people).

Males of many webspinner, such as this cosmotropical Oligotoma saundersii, are fully winged. Their wings can easily flex in half over the top of the body to help them move backward in the narrow silky corridors.

Males of many webspinner, such as this cosmotropical Oligotoma saundersii, are fully winged. Their wings can easily flex in half over the top of the body to help them move backward in the narrow silky corridors.

The first thing that I noticed was that many tree trunks in the forest were covered with extensive carpets of silk. This was great because for the last two years I had been searching in Gorongosa for the elusive webspinners (Embiidina), an order of semi-social insects that build intricate silk corridors on trees and rocks. No species of webspinners has ever been recorded from Mozambique but I knew that they had to be there. To be precise, I did find a webspinner once in Gorongosa, but it was an introduced, Asian species Oligotoma saundersii, which has a nearly cosmotropical distribution. But the animals on the trees of the sand forest were clearly something very different.  For one, they were huge. I am used to webspinners being tiny, brownish insects that you look for with a magnifying glass. But one adult female that we collected was pitch black and nearly 25 mm long, which probably makes her the largest webspinner in the world (the largest webspinner that I could find a record of is the South American Clothoda, which grows to 20 mm.) But despite their size these insects were not easy to find. I ripped through dozens of their silky colonies but found only a handful of specimens. Only later did I realize that during the day these insects were hiding deep in the crevices at the base of the tree or in debris-filled nooks between branches.

The thin sheet of silk acts as an invisibility cloak, protecting foraging webspiners from their principal enemies, ants.

The thin sheet of silk acts as an invisibility cloak, protecting foraging webspiners from their principal enemies, ants.

Webspinners have fascinated me for a long time. They are one of those animal groups that don’t attract much attention because of their small size and unassuming physique but, once you learn about their biology, they become very hard to ignore. The webspinners’ most obvious claim to fame is their ability to spin silk. But how do they do it? Spiders spin silk from spinnerets located at the tip of their abdomen (opisthosoma), but all insects (caterpillars, ant larvae, gryllacridid crickets, to name a few) have them located on their mouthparts. Or so the entomologists thought. And so strong was this conviction that early morphological descriptions of webspinners included silk-producing tubercles on the labrum which, upon closer inspection, turned out to be purely imaginary – as it happens, webspinners possess unique silk-producing, glands on their front tarsi, and not on their mouths. This explains their characteristic behavior of constantly waving the front legs – they are spinning silk, but the individual strands as so microscopically thin as to be completely invisible to the human eye. Only once hundreds or thousands of individual strands have been spun together do they begin to appear as a thin sheet of soft silk. The proteins that make up the spider and moth silk are some of the strongest organic compounds, resistant to breaking and very flexible. In contrast, the webspinners’ silk is remarkably weak and tears quite easily. This may have to do with its primary function – rather than being used to capture prey or protect a fragile developing pupa, it is merely a cloaking device that makes the insects invisible to ants while the webspinners graze lichens that cover bark or rocks. I have watched ants walk right on top of webspinners separated only by a diaphanous sheet of silk, while the webspinners were happily grazing on lichens, completely unperturbed by the presence of their deadly enemies.

The second function of the silk is the protection of eggs, which the female covers with silk and guards them until they hatch. She stays with the eggs mostly to chase away parasitoid scelionid wasps and plokiophilid bugs, and her presence increases the survival of eggs by 50%. But once the eggs are about to hatch the mother must remove the silk, otherwise the nymphs will not be able to emerge. She then stays with her children until they are ready to fend for themselves, initially masticating their food and spinning the silk corridors. She then leaves to start another colony.

The front tarsi of webspinners are strongly enlarged to accommodate silk-producing glands.

The front tarsi of webspinners are strongly enlarged to accommodate silk-producing glands.

Interestingly, some webspinners are the only social insects that are inquilines within the societies of other social animals – two species of Oligotoma from India build their societies inside colonies of a social spider Stegodyphus sarasinorum (but continue to spin their own silk). Another, Oligotoma termitophila, lives in termite colonies in Sudan.

So, what’s next for my Mozambican webspinners? Next time I am in Gorongosa I plan to look into their biology, and figure out what their colony structure and dispersal patterns are. The species also needs to be identified and described, which I should be able to do once I bring the specimens back from Mozambique (we hit a little snag with the export permits). I also plan to look for other species on Mt. Gorongosa. Who knows, I may also be able to find the webspinners’ closest relatives, the amazing zorapterans.

Silken galleries of webspinners covering trees in the Sand Forest of Gorongosa.

Silken galleries of webspinners covering trees in the Sand Forest of Gorongosa.