When you look at the carapace, you will see a pair of median
eyes in the centre and on the sides 1-6 pairs of lateral eyes. Scorpion eyes are simple but have been found to be remarkably
sensitive. The median eyes are more sensitive than lateral
Generally, the leg
is divided into:
coxa (closest to sternum), trochanter, femur, patella, tibia,
basitarsus and tarsus. It ends with the pair of ungues (lateral
Used for locomotor function and may be used to dig.
Pedipalps (includes claws)
The pedipalp is divided into:
coxa, trochanter, femur, patella, tibia and tarsus. The tibia
and tarsus forms the chelae of the pedipalp. The pedipalp
contains many hairs (setae). The setae give spatial
orientation. The pedipalps are used to grasp prey and for
defence against predators. The pedipalps are also used to grasp
female chelae while mating.
Divided into 3 segments: coxa, tibia (fixed finger), tarsus
(movable finger). Used to grasp and crush prey before sucking
The dorsal carapace is called tergite while the ventral is
called sternite. They are joined by a whitish membrane called
pleural membrane which would be stretched when the scorpion is
very full or pregnant.
The mesosoma is divided into 7 segments.
The metasoma is divided into 5 segments and the sting. The
sting is called the telson. There are generally 2 venom glands
under voluntary control within the telson. The telson ends with
a hypothermic needle like sting known as an aculeus. The telson
is divided into two parts; the vesicle and the aculeus.
Sternum is the junction where the coxae of most legs meet.
Genital operculum covers the reproductive organs of the
scorpions (genital orifice of females). In the male, the genital
operculum is usually partially or completely separate. A pair of
genital papillae may protrude from the posterior part of the
operculum for males of some species. This is another key sex
A peculiar gill like structure. The function of the pectines is sensory. It is one of the most convenient means of
determining sex of some species. Pectines are larger and longer
Small external opening of a book lung as found in scorpions and
spiders. There are four pairs in scorpions and up to two pairs
Type of respiratory organ found in certain air-breathing
arachnid arthropods such as scorpions and some spiders. Each
book lung consists of a series of thin plates that are highly
vascular (richly supplied with blood) and arranged in relation
to each other like the pages of a book. The plates extend into
an internal pouch formed by the external skeleton that opens to
the exterior by a small slit (spiracle). This opening provides
extensive surface area for the exchange of oxygen and carbon
dioxide with the surrounding air. There are four pairs in
scorpions and up to two pairs in spiders.
The easiest way to find scorpions is at night using an ultraviolet torch. The presence of β-carbolines in the cuticle of their skin fluoresces when exposed to certain wavelengths of UV light.
It isn't really understood why this happens. Some arachnologists speculate that scorpion fluorescence has no function at all. Perhaps it's just a random act of evolution. Others theorise that it may be used as a way to determine whether or not to come to the surface to look for prey, based on light levels, as there is a UV component in moonlight, or to avoid being too exposed at full moon. Others still say that the fluorescence may help to prevent overheating by effectively re-radiating solar energy.
Some researchers say that newly moulted scorpions do not
fluoresce until 48 hours after shed. I have experienced otherwise. Other researchers say that 2nd instar scorpions don't
fluoresce. Again, I have experienced otherwise.
to my knowledge, only 1st instar scorpions do not fluoresce.
Scorpions with a dark colouration such as
Parabuthus transvaalicus tend to
fluoresce luminous turquoise. Scorpions with light colouration such as
Parabuthus capensis tend to
fluoresce luminous yellow.