Understanding scorpions
Jonathan Leeming
 Although scorpions are probably one of the most recognizable animals in the
world, few creatures are as enigmatic or feared. Even in this modern world,
misconceptions still perpetuate amongst most people. Scorpions are secretive
creatures that usually retreat at the slightest disturbance. In many habitats
they represent a major predatory force acting upon a variety of small creatures.
Scorpions evolved from aquatic creatures that lived some 450 million years
ago, way before the dinosaurs existed. In those early days of evolutionary
experimentation, they attained a length of over 1m. Scorpions have since then
scaled down in size and have wedged themselves into their own niche habitats
within the general environment.
Scorpion spotting - not in your shoe
It is difficult enough finding these creatures during the day, but at night
it is a different story. When looking for scorpions scientists use an
ultraviolet light. At night, under normal torch light (white light) scorpions
are impossible to detect. Their cryptic colouration and ability to hide at the
mere flicker of a light makes them difficult to locate. Under Ultra Violet (UV)
light however, scorpions emit an eerie greenish glow. On dark nights small
species can be seen from many meters away. It is not uncommon to see over 200
individuals in good scorpion habitats. We do not understand why they glow, but
they do. "Unfortunately, warthog holes, barbed wire fences and large
mammals do not glow under UV light making scorpion collecting an exciting
pastime in big five country," jokes scorpion expert Jonathan Leeming.
"Survival guides to the outdoors always amuse me because they amplify
the 'fact' that scorpions will crawl into you shoe if left outside," says
Leeming. Even scarier was the suggestion by one book to always check under the
toilet seat for scorpions. According to Leeming, the truth is that the average
scorpion wouldn't find your shoe or sleeping bag an inviting place to shelter.
Southern Africa does contain more than a few places where highly venomous
species abound, and where leaving ones shoes, clothes outside is not advised.
Stings from these highly venomous creatures are extremely painful but rarely
fatal. Under certain conditions scorpions may leave their burrows or become
nomadic.
The sting
All scorpions posses neurotoxic venom. Their venom is fundamentally similar
and therefore antivenin can be applied across the board. Scorpion venom is a
complex mixture of neurotoxins each part performs a certain function. Functions
include pain-inducing components for warding off predators, or toxins aimed at
immobilizing specific groups of creatures such as insects, and even courtship.
Southern Africa has an extremely low mortality rate when it comes to scorpion
envenomations. On average a dozen or so fatalities are recorded annually. Thanks
to the availability of good medical facilities and antivenom, deaths in southern
Africa are few indeed, usually restricted to infants and the aged. These figures
pale in comparison to countries such as Mexico where on average 2000 people die
annually as a direct result of scorpion stings.
 It is interesting to note that southern Africa is host to one of the world's
least venomous scorpions belonging to the genus Hadogenes. Although Hadogenes
sp. venom is virtually harmless they do sport a pair of powerful pincers capable
of splitting fingernails. A member of this genus also holds the record for the
longest scorpion in the world, attaining a length of over 21cm. A few more can
even spray venom in defense. If the sprayed venom gets in the eyes it is a
painful and visually impairing ordeal. Survival guides come to the rescue in
this respect and recommend washing out with any bland fluid, even urine.
Pecking order
Scorpion population dynamics has long since fascinated Leeming. On early
collecting trips it was clear that on some nights only certain species were
found. On other nights other species abound. When contemplating this phenomenon
it becomes easier to understand if you look at it from a scorpion's perspective.
 Scorpions have a pecking order. Maybe it should be called a
"munching" order since large species of scorpion often prey upon
smaller species. Although scorpions are immune to their own venom, their venom
does have a significant effect across species. Depending on the species
structure that exists within a habitat, these dominant species are aggressive
hunters, often highly venomous and large in size. They prey upon the smaller
species found in the same habitat. When these dominant species abound, smaller
species tend to be unseen. This is not because they have all been eaten. They
avoid being preyed upon by the more aggressive species by avoiding them and
being active when conditions do not suit other species. Smaller species often
hunt in vegetation, a place where large creatures find it hard to move through.
Hunting techniques play an important role in encounters with humans. The
majority of species are opportunistic, preying upon anything they can overpower
that comes within striking distance. Often species ambush their prey from the
periphery of their shelters, be it a burrow, crack in a rock or tree. It is
interesting to note that our two most venomous species have a wide distribution
and their hunting techniques depart from the typical sit-and-wait style that
most scorpions practice. Parabuthus transvaalicus and the more venomous Parabuthus
granulatus are two species that actively forage for prey at night. They are
almost arrogant in their foraging strategies as they march around seemingly
defiant of human observation.
Habitat
 Many species have very specific habitat requirements. In some cases their
distributions can be mapped back to rock types, sand systems and substrate
composition. A good example of a close relationship is Opistophthalmus holmi
which is confined to the Namib sand system in Namibia. Highly evolved
specializations ideally equip this small scorpion to life in a sea of shifting
sands. On sand, these specializations help the scorpion to walk, feed and hunt,
however in foreign habitats this species would be like the proverbial fish out
of water. Very few species have extensive distributions that extend over varying
types of terrain and habitats. Species that invest time and energy into shelter
construction would not leave their shelter easily. In habitats where shelters
cannot be created they must be found in the natural environment, scorpions do
not just abandon these for any reason. Although more scorpions can be found in
the more arid parts of southern Africa, scorpions can be found in almost every
terrestrial habitat except the high mountain peaks of Lesotho.
Scorpions have incredibly slow metabolic processes which enable them to wait
out unfavourable conditions. It's estimated that some burrowing species spent up
to 95% of their entire life inside their burrow. Other experiments describe how
a scorpion was frozen in ice and remained relatively unharmed after a bit of
defrosting. Some species rarely drink water as their prey contains all their
water requirements. Other species have been known to go without food for more
than a year. During the winter months in southern Africa, scorpions are often
very difficult to find. Burrowing species simply close up the entrance to their
burrows and wait for conditions to improve. When conditions are right, mass
emergents of scorpions often described as plagues occur. Factors such as
rainfall and temperatures are often the cue for such events.
Through no fault of their own, scorpions have a bad reputation. It seems like
the only time we hear about these creatures is when someone is stung or even
dies. Beyond their venomous tendencies lie complex behavioural patterns and
intricate lifestyles. As scientists delve deeper into the private lives of these
creatures we can only learn from these living fossils and develop a greater
understanding of these fascinating creatures.
More information:
Jonathan Leeming:
Jonathan@scorpions.co.za
http://www.scorpions.co.za
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