Spider Tales 2: The Camel Spider

 As the tale goes, American troops encountered a monstrous animal in the deserts of Iraq: the most terrifying spider ever seen.
Gigantic, with a foot-long (30 cm) body, it has ten legs, can run at 25 mph (40 km/h) while emitting blood-curdling shrieks, and jump horrifically high.
But hang on, that's not even the worst part. The worst part is what, and how, it eats: it can devour camels. Yes, CAMELS, hence its name: camel spider.
Armed with a painkilling venom, it will chew on a sleeping animal's flesh without awakening it. Unlike other spiders, which dissolve and suck their prey's contents, the camel spider has enormous, wickedly sharp chewing mouthparts, that can tear through meat with ease.
It is only when it wakes up that the unsuspecting prey discovers the bloody gashes left by the arachnid... Provided it ever wakes up.
Of course, if camels are fair game, humans are also on the menu, and soldiers in the field have woken up with horrifying, gaping wounds...

Sounds like absolute bullcrap? It's because it is. All of it. Not even a tiny kernel of truth at the center. It's all pure, silly, far-fetched fiction. However, in the early 2000s, these tall tales, illustrated with out-of-context, often photoshopped gory images, written and shared by people unable to tell a real animal from a fishing lure, made the rounds on the Internet. And despite how ridiculous it all sounds, some actually believed it.

While it's still sometimes taken seriously, this hoax is getting old (some might even say historical), and has been abundantly debunked.
Nowadays, camel spider legends are mostly told jokingly. Colourful accounts, for instance, from French troops about "araignées-couteaux" ("knife spiders") in Djibouti, similar to the American camel spider myths, suggest that they are used there to scare and prank newcomers, just like drop bear stories in Australia.
In 2011, camel spiders, as depicted in the digital folklore, have even starred in an intentionally cheesy horror movie, produced by Roger Corman (to whom we must be thankful for other "masterpieces" such as Dinoshark (2010) and Supergator (2007)). 

However, behind these ridiculous tall tales, hides a real animal, as unjustly feared as it is poorly known. Camel spiders are harmless arachnids, whose fearsome appearance and misunderstood behaviours have inspired myths since the Antiquity. While they're nowhere near as dangerous as people want to believe they are, they're even stranger than what's depicted in the legends; weirder, actually, than most science-fiction creatures.
Meet the Solifugae.

This creature is harmless and doesn't want to hurt you. No, really.

1. A profusion of names*

While they rose to Internet fame as camel spiders, these animals bear, throughout the world, a plethora of common names, so many that the following list is far from exhaustive. 

Of course, the name "camel spider" doesn't come from any camel-eating abilities, but more probably from their humped and hairy appearance, and tendency to thrive in deserts.
Other widespread names in the English-speaking world include sun spiders, wind scorpions, solpugids or solifugids. In some parts of the USA, they're also apparently called "jerrymanders" or "jerrymunglums". 

In Spanish, they're known as "araña del sol", which, like "sun spiders", probably refers to their preferred arid habitats.

In German, they're called "Walzenspinnen" (rolling/steamrolling spiders), or "Scorpionspinnen" (scorpion-spiders).

In French, they are sometimes called "galéodes" (from an old Greek word meaning "shark") or "araignées-couteaux" (knife spiders), but the most common name for them is "solifuge", a Latin word which means "flees from the sun". 

Speaking of Latin, ancient Romans knew these animals as "solfugae" or by their Greek name, "Phalangia (singular : "Phalangion")" (a name that also referred to very large spiders and harvestmen) and already told crazy tales about them.

However, Southern Africa probably takes the cake for the most imaginative and interesting names:
the most common name there is "roman", an enigmatic word which derives from the Afrikaans "rooi man" (red man), and is sometimes found as "red roman" (which is redundant, as the "ro" part of the name already means "red").
The Afrikaans names "haarskeerder" and "baardskeerder" ("hair-cutter" and "beard-cutter") refer to a local myth, according to which they cut hair from sleeping animals and humans to line their nests.
Recently, another fun name has been quickly gaining popularity: the "Kalahari Ferrari".

Worldwide, scientists know them as Solifugae, or solifuges.

2. An immense range

If Solifuges have so many common names in so many different languages, it's not just because of the myths they've inspired: it's also because they're extremely widespread.
While modern legends depict them as creatures from the Near and Middle Eastern deserts, they actually occur on every continent except Antarctica and, strangely enough, Australia.

The vast majority of Solifugae species prefer open, arid habitats, and their range roughly reflects the distribution of the planet's deserts, semi-deserts and dry steppes.
Their maximum diversity is in Africa; South Africa alone is home to more than 160 species. They're found almost everywhere on the continent, except in the Central African rainforest and Madagascar. 

Widespread in the drier regions of Asia, they only marginally enter Europe, where they are restricted to the Iberian peninsula, some islands of the Mediterranean sea, and the extreme southeast of the continent (Greece and Northern Macedonia, Bulgaria, Ukraine and Russia).

Ironically, although the American legends about them rely heavily on the "foreign threat" narrative, they do occur naturally in the USA. The southwestern US is actually one of the places of the planet where they're the most diverse!
They're also abundant and diverse in Mexico, and present in Central America and the Caribbean. In South America, they're found roughly everywhere, except in the dense forests of the Amazon basin.

Their absence from Australia is a bit of a mystery, as, at first glance, the Outback would look like prime habitat for them, and Solifugae, as a group, are much older (at least 300 million years old) than the break-up of the Gondwana (the giant landmass which included Africa, South America, India, Antarctica and Australia, which started breaking up about 180 My ago).
It is not known whether they used to occur in Australia but went locally extinct at some point, or if, for some reason, they never managed to set foot on the Land Down Under. The fossil record of solifuges is extremely scarce, so we may never know. 

Global range of Solifugae (source)

3. Camel not-spiders

Despite what many of their common names imply, camel "spiders" aren't spiders. They aren't scorpions either, and, despite a weirdly widespread belief in Southern Africa, they are also not related to ants.
Like spiders (Araneae), ticks and mites (Acariformes and Parasitiformes), scorpions (Scorpiones), vinegaroons (Thelyphonida) or harvestmen (Opiliones), they're one of the 11 to 13 orders in the class Arachnida, the arachnids.

Worldwide, there are about 1100 species, in 140 genera, in 12 families, in the order Solifugae. Although it's easy to recognise a solifuge, identifying the exact species, or even the exact family, is often quite difficult, and requires expert knowledge of the group.

While there's no doubt they are arachnids, their exact position in the class (i.e. who, among the other orders, are their closest relatives) is still an unanswered and difficult question. Many studies suggest they're most closely related to pseudoscorpions (which are not scorpions nor close relatives of scorpions), but some place them as closest to Acariformes, one of the two orders of mites. 

One thing is certain, though: they're not very closely related to spiders, and a trained eye will immediately spot obvious differences. 

A large female solifuge (from the family Solpugidae)

 

For comparison, a baboon spider (cf. Harpactirella sp., family Theraphosidae)

One of the most obvious differences is the segmentation of the cephalothorax (the front part of the body, where the legs are attached): in spiders, as in most orders of arachnids, the dorsal side of the cephalothorax is covered with an unsegmented shield, the carapace, which bears the eyes. Meanwhile, in solifuges, there's a visible segmentation: a clearly distinct, bulbous "head" (the propeltidium), in front of a segmented, flexible thoracic part, a unique feature among Arachnids.

Compared to most other large arachnids, Solifugae have a highly reduced exoskeleton, and large parts of their body are covered in soft connective membranes. This gives them exceptional flexibility and agility, allowing them to twist an turn with ease, to move very quickly, and to suddenly change direction as they run.

While most spiders have lost any visible segmentation on the abdomen, solifuges also have a segmented abdomen.

However, the differences with spiders don't stop there...

No silk for solifuges...

One of the most conspicuous features of spiders is their ability to produce silk, which plays a major role in their lives. Wrapping their eggs, building shelters, trapping and subduing prey, flying... are only some of the uses spiders make of that amazing material.
Spider silk comes out of spinnerets, which are found on the abdomen (the baboon spider illustrated above has long spinnerets protruding at the tip of its abdomen); spinnerets are the most complex silk-producing apparatus found in Arachnids.

They are, however, not the only ones able to spin silk. Pseudoscorpions and some mites also have silk glands, although the use they make of it is more limited than in spiders.

On the other hand, solifuges, like scorpions or harvestmen, completely lack silk-producing organs. They can't spin webs, shelters or egg sacs. To protect themselves from the scorching sun, they use a very widespread strategy among small desert animals: they dig burrows. 

A solifuge burrowing in the sand

As, unlike spiders, they cannot consolidate the walls of their burrows with silk, they need to be very careful in their choice of substrate. This is one of the reasons why solifuges are extremely picky when it comes to habitat, one species often only occurring, in a given environment, in one or a few types of micro-habitats, with specific soil and vegetation types (and different species in the same area can have different micro-habitat requirements). 

And (apparently) no venom either!

It's THE question that always comes to mind the first time one sees a solifuge: is it venomous?
An understandable concern when one looks at these giant, bulbous chompers. Legends, modern or ancient, tell of nasty consequences following their bite... 

Meanwhile, academic sources agree about the harmlessness of these animals to humans, besides a possible risk of infection (which comes with any open wound from a non-sterile object, however small it may be) if the jaws manage to break the skin.
However, the question of venom secretion by Solifugae is a tad more complicated than it initially seems. In 1978, glands in the chelicerae of  a large solifuge species from India, Rhagodes nigrocinctus, were discovered and interpreted as evidence of a possible venomous apparatus, as, injected in geckos, the product of these glands was shown to induce paralysis. Meanwhile, the search for a similar apparatus in other solifuge species has not yielded any results, and the venomous function of these glands in R. nigrocinctus was questioned. 

Therefore, unlike spiders, scorpions or pseudoscorpions, solifuges are not regarded as venomous, though one or some species in the family Rhagodidae might be an exception. Still, venomous or not, they are not of any medical concern to humans. 

Two eyes?

While spiders can have 8, 6, or more rarely, 4, 2 or no eyes, Solifugae seem to only have one pair of visible eyes. 

Relatively large, round and black like those of a plush toy, the eyes are positioned at the very front of the propeltidium (the "head"), on a small tubercle that slightly protrudes over the anterior edge of the carapace.
Interestingly, while it's the only visible pair of eyes, it's not the only one: there's also a second pair, a vestigial eye on each side of the head, hidden under a flap of integument. While the role of those hidden eyes is a mystery, they are pigmented, and appear to be functional in some species.

Sight (at least from the main pair of eyes) seems to play an important role in the solifuge's life and navigation: when their eyes were experimentally obscured, individuals of some species seemed seriously impaired and had a lot more trouble locating prey. Meanwhile, some other species didn't seem quite as affected, suggesting different species rely on different senses for hunting.

Ten legs!? 

When compared with spiders, Solifugae display one last, striking difference : there seems to be something weird going on with their legs. The last pair of legs is long and sturdy, pairs III and II are shorter, but just as powerful, pair I is short and slender, and then... There's a fifth pair? Ten legs? Don't arachnids always have eight legs?

Six, eight... Ten legs? Something's odd... (Galeodidae, dry specimen)

In fact, just like every other order of Arachnids, Solifugae have eight legs. The fifth pair of "legs" is actually not legs. It's a pair of pedipalps.
While legs and chelicerae ("jaws") are pretty consistent in their structure and function from one order of Arachnids to another, pedipalps are interesting because they vary considerably in these aspects.
In scorpions and vinegaroons, for instance, pedipalps are transformed into powerful grasping claws. In pseudoscorpions, they're grasping claws equipped with a venomous apparatus. In female spiders, they look like miniature legs and are used for holding and tasting food, whereas in male spiders, they're transformed into a copulatory organ used for inserting sperm into the female's genitalia.
In Amblypygi and some harvestmen, they look like impressive torture implements, covered in sharp spines, which are used for capturing and killing prey.

In Amblypygi, pedipalps are large, powerful and covered in sharp spines, used for capturing and killing prey (image by Jérémie Lapèze)

In solifuges, on the other hand, they look like long, thick legs; however, they're not what they look like. At all.

4. Master hunters

Swiss army pedipalps

Whoever is lucky enough to observe a live solifuge will quickly notice that, despite their resemblance with legs, their pedipalps aren't for walking. The last three pairs of legs propel the animal at dazzling speed, while the first pair is held still, in constant but slight contact with the ground. Meanwhile, the pedipalps are held outstretched in front of the body, waved up and down, sometimes gently tapping the ground.
These movements are evocative of a sensory function, and their pedipalps are indeed incredibly sensitive, bearing all sorts of sensory receptors. Most of these receptors are hair-like structures (setae) that cover the appendages, and pedipalps in particular. 

Detail of a Galeodidae's pedipalp, bearing different types of setae and sensilla (magnification x25)

Many of these setae are mechanoreceptors, sensitive to touch, ground and air vibrations. Some others, hollow, are chemoreceptors, detecting smells; each pedipalp has hundreds of them. 

Equipped with these receptors, pedipalps act as incredibly efficient prey detectors, which a hunting solifuge will wave around and tap on the ground in order to spot vibrations and smells, like a miniature bloodhound. The sensory apparatus of Solifugae is so powerful that they can detect, from the surface, a burrowing insect hiding under several centimetres of soil.  

While pedipalps are a crucial part of the solifuge's sensory arsenal, they're not its only navigating tools. Legs, particularly the first pair, also play an important role in detecting ground vibrations, and the entire body is covered in different types of sensory setae. Finally, there are the malleoli, strange white, soft, fan-shaped organs on the underside of the body at the base of legs IV. While their exact function is still poorly understood, it is quite clear that the malleoli have a sensory role. More specifically, they seem to be chemoreceptors, but, despite how they're positioned on the body (which would, at first glance, make them look ideal for detecting ground vibrations), appear completely devoid of mechanoreceptors. 

These keen senses make Solifugae highly skilled hunters; however, the role of their pedipalps doesn't stop at navigation and prey detection. When the prey is within reach, these multifunctional appendages become a bizarre weapon. 

The tip of a solifuge's pedipalp (magnification 44x)

 

Where legs (except, generally, the first pair) end in a pair of long claws, very handy for finding a good grip on uneven ground, the tip of the pedipalp is a blunt, bell-shaped tarsus.
This bell-shaped structure hides, behind two flaps of cuticle, a retractable organ, known as the suctorial organ.
When the suctorial organ is used, the flaps open and a little tongue-shaped, flattened pad comes out. This little pad is incredibly adhesive, strongly sticking to anything it touches. Like the fingers of a gecko or the scopula (adhesive leg brushes) of a spider, the tarsal organ sticks not with glue, but with nanoscopic asperities and ridges, which grip the substrate thanks to the Van Der Waals force.
These little "suckers", combined with the animal's lightning quick reflexes, are a fearsome weapon, used for grabbing onto fast and agile prey items, such as flying or jumping insects. Despite their small size, these pads are so sticky that they can hold onto a large, struggling, somersaulting cricket, and toss it, in the blink of an eye, between the solifuge's enormous chelicerae.

Jaws

It's about time we address the elephant in the room: the chelicerae. These enormous, toothy, gnarly beak-like jaws, often as large, or larger, than the animal's entire cephalothorax...
It's safe to assume they're the very first thing you noticed when you laid eyes on a solifuge for the first time, in flesh or in pictures. It's difficult not to wonder what kind of nasty venom those hellish chompers could inject into your vulnerable and terrified flesh... 

The chelicerae of Solifugae are often as large as the entire prosoma (the front part of the body)

However, we've seen previously that if they bit you, these jaws wouldn't inject you with anything too harmful. Actually, they wouldn't inject anything at all. Unlike a spider's hollow, syringe-like fangs, the solifuge's chelicerae are claw-like and function as shears, cutting and crushing. They don't have any internal canal for injecting substances.

Detail of a solifuge's chelicerae. The bottom finger is the movable one, the top one is fixed.

The scissor-like fingers are operated by very large muscles, which give a bulbous aspect to the base of the chelicerae, where they are attached. 

The force developed by these muscles varies from one family of Solifugae to another (for instance, the chelicerae of a Rhagodidae are stronger than those of a Galeodidae), but is, overall, comparable to the jaws of other Arthropods, such as cockroaches, spiders, mites or crabs. Thus, despite what's commonly assumed and said about these arachnids, their bite force is not, proportionally, much higher than other Arthropods' mouthparts. What makes their bite so powerful is the large size of the jaws and muscle apparatus, and the teeth, which concentrate the pressure of the bite on small areas. Thus equipped, Solifugae are able to break tough exoskeletons and slice through the flesh of small animals with ease. 

As they are deprived of any venom allowing them to subdue their prey, they can only hunt and kill what they can overpower with the sheer force of their chelicerae. They are thus more limited in that aspect than venomous arachnids, such as scorpions and spiders, and rarely feed on animals much larger than themselves (although they won't hesitate to have a go at fairly large prey if they're soft-bodied and devoid of any serious defences, such as small nonvenomous snakes).

Once the prey is caught and incapacitated, the chelicerae will also serve in carefully chewing on and crushing its flesh into mush, while soaking it with digestive enzymes, in order to liquefy it. Like most Arachnids, a solifuge's mouth is merely a sucking tube, which can only ingest pre-liquefied food. 

While feeding is, of course, the primary function of the chelicerae, the solifuge also uses them in a lot of other ways. When they don't serve as steak knives, the chelicerae also make decent pickaxes for digging. A burrowing solifuge will attack the ground with its jaws to loosen it, then use its legs and pedipalps to push away the loose soil. 

A solifuge starting a burrow, biting at the ground to loosen it

Finally, when things go south, chelicerae will also have to serve as defensive weapons against potential predators. Mainly for the bluff, though; while these jaws are great at dispatching small animals, they aren't really capable of causing any significant damage to a large attacker.
Best they can do is a mean pinch, akin to what a crab with similarly-sized claws could inflict; while it's definitely painful, it's often not even enough to break human skin. 

It may be all bark and not much in the bite department, but a defensive solifuge does, however, look quite fierce and impressive.
It will rear up and stand its ground, legs and pedipalps raised up, displaying its wide open chelicerae, rubbing them together to stridulate.
While the "shrieking" of camel spider is pure myth, their stridulation, which sounds like little squeaks or clicks, is definitely audible by the human ear, although it is, to us humans, rather cute than actually scary.

Another significant feature of their defensive stance is the way they raise their abdomen vertically. This position has been interpreted as a way to protect it, as it is the most vulnerable of their body parts, but also as possible mimicry. When they do that, some species (particularly the short-legged, long-bodied ones in the family Rhagodidae) indeed superficially resemble a scorpion ready to sting. 

If all this is still not enough to deter the assailant, the solifuge may charge or lunge and try to bite, which can't do much, but will at least elicit surprise and puzzlement, and hopefully create an instant of hesitation, that the arachnid can exploit to flee as fast as it can.

They do look impressive, but how big are they?

Of course, the foot-long monsters of the urban legends are completely fictional, but Solifugae can nonetheless reach respectable sizes. The smallest species are only about 1 cm long (legs and pedipalps excluded). Their average size is around 3 or 4 centimetres, while the largest, such as some Galeodes spp. or some species in the family Solpugidae, can reach over 7 cm in body length, for a total length of about 15 cm (0.5 ft), all appendages included.

An extremely large Galeodes sp., with a total length (appendages included) of exactly 15 cm

A very small solifuge (probably in the family Daesiidae) with a total length of about 3 cm

While they typically don't go after animals much bigger than themselves, their fairly large size gives them access to a wide range of prey. Larger Solifugae can take on tiny vertebrates, such as small lizards, snakes or frogs, but the bulk of their diet is insects and other Arthropods. Although some species are specialist termite hunters, most are opportunistic and will gladly sink their chelicerae into anything they can catch and overpower.

For this 3 cm long dwarf gecko (Goggia sp.), the night is dark and full of terrors... as it's a perfect snack for a large, hungry solifuge

 

Unfortunate gladiators

A solifuge can and, if it has to, will confront a scorpion; however, despite a widespread (and very old) belief, they do not have a particular appetite for them. If the necessity arises, its sharp jaws and quick reflexes give the camel spider a fair chance in a fight, and it will, apparently, immediately try to disarm the opponent by lopping off its tail. If the contenders are evenly matched in terms of size, the odds are generally in favour of the solifuge. 

XIXth century engraving (author unknown) showing a solifuge fighting a scorpion (source)

The outcome, though, isn't exactly predictable: Solifugae are not immune to scorpion venom, so all it takes for a quick and inevitable death is one wrong move. In a significant number of instances, swift reflexes and sharp chelicerae won't be enough...
It does therefore make sense that, in the wild, scorpions and solifuges will try their best to ignore and avoid each other, and focus on easier prey. 

Even for a large solifuge, this huge burrowing scorpion (Opistophthalmus leipoldti) is a formidable opponent, to which it will give a wide berth...

The reason why, like mongoose and cobra, they're often perceived as natural enemies, is that some people like to kill boredom by catching these animals and pit them against each other in an enclosed "arena". As flight is not an option in this unnatural situation, they have no choice but to fight for their lives. 

5. Live fast...

Breathtaking stamina

"Frantic" is undoubtedly the term that best describes Solifugae. Hunting, eating, digging, running, everything they do is done in a state of hectic agitation. 

In this aspect, they differ radically from scorpions and spiders, which can move very fast, but generally in a sprint-and-pause pattern (which makes them easy and fun to photograph), and will spend much of their time resting and standing still. 

Spiders, including the lightning-fast flatties (Selenopidae) generally move in a sprint-and-stop pattern, and spend a lot of time motionless

Solifugae, on the other hand, move almost continuously: running, walking, frequently and unexpectedly changing course and pace, they rarely ever pause (and are, therefore, an absolute pain to photograph).

The secret of their superior stamina is their respiratory system, which is completely different from what spiders and scorpions are equipped with. While the latter have booklungs (spiders have booklungs and tracheae, or only one of the two), which function, as their name indicates, roughly like our lungs, solifuges, like, for instance, insects and harvestmen, breathe through tracheae. 

Lung-like respiratory systems, such as booklungs or true lungs, are pouch-like structures, equipped with an opening that allows outside air in, and lined with a thin, convoluted, and heavily irrigated surface in contact with the air. As the hemolymph (Arthropod blood-like fluid) circulates under this surface, oxygen molecules from the air get dissolved in it, while CO₂ is released from the hemolymph into the air. Then, the fluid transports dissolved oxygen to the organs.

Tracheae, on the other hand, are tubes that split into increasingly thinner, smaller and more numerous branches, all the way down to the organs, muscles and other tissues. Air, which enters the trachea through an opening called a spiracle, therefore travels, as a gas, almost directly to where it is needed.
The fact that oxygen, in the tracheae, travels to the organ in gaseous, instead of dissolved form, makes a huge difference, as oxygen transfer is much faster and more efficient that way. This important oxygen supply is what allows Solifugae to live such a fast-paced life. 

At rest, the solifuge's heart rate and oxygen consumption drop considerably, and the animal can enter a torpor-like state, which saves energy and allows it to survive the low-oxygen conditions of its burrow.

Of course, this hectic lifestyle, indicative of a very high metabolic rate, is also extremely costly in terms of energy. Compared to other arachnids such as spiders and scorpions (scorpions in the wild often eat once a month to once or twice a year!), Solifugae are incredibly voracious: a tiny (5 mm) juvenile Galeodes sp. was observed devouring 100 flies in 24h!
While scorpions and spiders are masters of the "low and slow", sit-and-wait, lifestyle, which requires very little energy intake, Solifugae have a "fast and furious" approach to life: move a lot, eat a lot.

Fast runners... But not record breakers

Because of their frantic movements, Solifugae look extremely fast. And they do, indeed, run very fast.
However, tales of camel spiders catching up on military vehicles, at speeds over 40 kph, are, of course, pure fabrications, and are completely unrealistic.
The same distance, for a small animal, is proportionally much longer than for a bigger one, as covering it will require more steps. To attain the same absolute speed, a smaller animal must therefore run at a much greater relative speed (in body lengths per second) than a large one. 

To a 5 cm long solifuge, an absolute speed of 40 kph would represent a relative speed of 220 body lengths (BL) per second!
In comparison, an absolute speed of 110 kph, the highest speed ever attained by a land animal, corresponds to a relative speed of 27.8 BL per second for a 1.10 m cheetah (roughly the body length, tail excluded, of a small female) in an artificial setup (they never actually run that fast in the wild, as they have to avoid obstacles and don't run in a straight line).

Of course, because their weight and aerodynamics are completely different, small animals are able to attain much higher relative speed than larger ones, but 220 BL per second would still be crazy fast...
Even faster, actually, than the fastest known land animal, the desert mite Paratarsotomus macropalpis, which runs at the breakneck speed of... 200 BL per second! A record this little arachnid can achieve because of its very small body (0.7 mm) which generates very little drag as it runs, its minute body mass, and the extremely high temperatures (43 to 60°C) at which it is active, which allow a very high metabolic rate. Solifugae could not attain such a high speed: their much larger, heavier body would generate too much drag, and the effort would be unsustainable. 

In more serious sources, one quite frequently finds a much more reasonable 12-16 kph as top absolute running speed for Solifugae, which would still be an impressive 88 BL per second in relative speed...
Impressive, but not improbable: other running arthropods, such as ghost crabs (genus Ocypode, 100 BL/s), the desert ant Cataglyphis bombycina (74 BL/s) or wolf spiders (75 BL/s), are in that range... And tiger beetles, the fastest insects on record, can run twice as fast as that (171 BL/s)!

Tiger beetles (Carabidae Cicindelinae) are the fastest insects on Earth

A top speed of 88 BL/s for solifuges would therefore be quite believable. However, this estimate unfortunately doesn't seem to be backed by any data from the academic literature, or any published measurements.
Available verified data about measured running speed in Solifugae are currently way below that: a Galeodes sp. was clocked at 53 centimeters per second, or 2 kph. That sounds disappointingly slow, but still equals about 10 BL/s... Usain Bolt, at his peak, runs at 6 BL/s!
Measuring how fast they can actually run is rather difficult, because they tend to constantly change their pace as they move around, alternating explosive sprints and slower walking, and making frequent, sharp turns.
It's quite possible that these bursts of acceleration, their quick, hectic movements, and the sharp, sudden changes of direction allowed by their extremely flexible bodies, make them look faster than they actually are.
It is, nonetheless, more than likely that they can run much faster than what has been recorded so far.

When they're active, solifuges cover a lot of ground in search of food, at an average speed which was measured, in the diurnal Namibian species Metasolpuga picta, as about 1 kilometre per hour. For an animal this size, maintaining such a speed over the course of several hours, and kilometric distances, is an incredible performance; while they may not be the fastest Arthropods, their stamina is certainly unmatched.

6... Die young 

 Maybe because of their very high metabolic rate, Solifugae are very short-lived, compared to scorpions or Mygalomorph spiders of similar size. Most of them live for one to two years, reproducing once or twice (depending on the species) in their lifetime.
Their growth is fast, and their adulthood generally lasts one to three months; females, which lay eggs and guard their offspring until they can fend for themselves, live longer than males.
As some keepers have managed to maintain adult female Solifugae in captivity for a year or more, it seems likely that, like some spiders, they are able to live longer if they don't have the opportunity to reproduce during their first year as adults.

7. Wild and free

Solifugae are harmless, very strange, and definitely spectacular arachnids. In addition to that, the urban legends have brought a lot of attention to them, and made a large public aware of their existence.
Because of all that, they're becoming increasingly common and sought after in the exotic pet trade.

The problem is that, unlike some other arachnids such as tarantulas, which can thrive as pets if provided with the appropriate conditions (conditions that are, for most species, fairly easy to replicate), solifuges tend to not handle captivity very well.
As they have a fairly short lifespan and are generally sold as adults or subadults, they rarely live long in a terrarium (although some have managed to keep one for more than a few months). In addition to that, their very special habitat requirements make it tricky to provide certain species with ideal living conditions.

While keeping them alive and healthy is not exactly straightforward but not impossible, breeding them successfully in captivity is extremely difficult. Even in the rare cases where captive breeding is achieved, it is often with a markedly higher mortality rate among the young than in nature.
Unfortunately, it means that virtually every camel spider on the market is wild-caught, with all the ethical and conservational concerns that the unregulated harvesting of poorly-known wild animals (which, on top of that, are basically impossible to reproduce in captivity) should always raise in any sensible keeper.
For the buyer, it also means that the animal's age and health condition are unknown, and that it could, even under outstanding care, die after a short while.

Thus, as awesome and fascinating as they are, it's best to refrain from trying to keep a solifuge as a pet. It's fairly unlikely to live a long and happy life in captivity, and, more importantly, every individual taken from the wild for the pet trade will be one fewer left to reproduce and perpetuate its species...

Camel spiders are best admired in their natural environment...

Speedy, greedy, ephemeral: Solifugae live their life in the fast lane. Although they're definitely as weird as the terrifying creatures depicted in the urban legends, we have nothing to fear from these otherworldly, tiny monsters. Inaccessible and secretive, fierce and and surprisingly fragile at the same time, there's still a lot to be discovered about these fascinating arachnids...⏹

 

 

*I know there are plenty of other names, in many other languages, that I'm not aware of. If you know these animals, in your language and/or area, by a name that is not listed here, please feel free to tell me in the comment section, and I'll be happy to add it.

References are integrated in the text of the article; the words in blue are clickable and will send you to the sources of the information.

Except when the source is explicitly cited, the images illustrating this blog are mine and are not free to use.
Images provided by Jérémie Lapèze are used with his consent and are not free of use.