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Navigation
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Note
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Pass
the mouse on the image, the legend posts
itself. When there is the hand click
on the part which interests you you will
be to bring to description.
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The
scorpions
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| Top of Vaejovis spinigerus male : |
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The
manus of pedipalps (more commonly
called chela or hand) are various
kinds, more or less large,
more or less smooth. They are useful
in the determination of the various families
and the sex.
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The
hand is composed
of
two parts, the tarsus or mobile finger
and the tibia, or fixed finger. Of course
it
is with
these articles
that the scorpion catches its preys,
but it also makes use of it like tool to
dig,
and
even like
shield to protect itself (Pandinus, heterometrus).
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The
pedipalps so called "maxillipedes" and
more usually "pincer" are composed
of 6 segments, namely: the coxa, the
trochanter, the femur, the patella, the
tibia (hand
and fixed finger) and the tarsus (mobile
finger).
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They
are especially used for seizing preys,
maintaining them in order to prick them,
and bringing them
to the chelicera. They are also
useful during the couplings, the male
then seizes those
of the female to proceed to the "promenade
à deux" before
fertilizing this one.
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Lastly,
the pedipalps are used by the scorpion during
its displacements.
The hands ahead, the scorpion palpates each
obstacle very often met it is as that which
it finds a
passage or the surged entry of one.
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The
chelicerae:
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The
chelicerae are composed of three
segments, the coxa, the tibia and the
tarsus, and resembles to a pincer, but smaller.
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They
are mainly employed to shred and crush the
preys in order to make
them assimilable. Indeed, it is with these
articles that the scorpion will mix enzymes
which go pre-digest the useful parts,
and just left with the end a pellet of what
is not assimilable.
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The
position of some hairs, and the teeth's
forms on the chelicera are used to differentiate
the species.
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The
eyes
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Scorpions
have two kinds of eyes. Median eyes, always
one pair, located at the top of the
prosomal carapace (cephalothorax), and one
at five pairs of lateral eyes, located on
the side of
the cephalothorax.
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In
general the scorpions have six eyes.
Some cavernicolous species, have
no eyes like, for example, Belisarius
xambeui in
France, Troglotayosicus vachoni in
Ecuador or Sotanochactas
ellioti in Mexico.
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Sternites
and tergites:
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The
plates dorsally bear the name of tergites,
those ventrally are named sternites. In
fact chitinous plates
protect the body from the scorpion, a
kind of all things considered shield. There
is always
7 tergites
and 7 sternites on the mesosoma.
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In
fact the hulls decorate these plates which interest
the
systematician
in order to determine the species and thus
to know to which family the specimen belongs.
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The
metasoma:
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The
metasoma, often called "tail" is
always composed of 5 segments (or rings)
articulated.
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On
these elements, one can find carinae very
useful into systematic to determine species
and
family of the specimen. For some species,
we
can also
determine the sex by comparing the
length of the segments of the metasoma. Males
have one much longer tail (Hadogenes, Centruroides,
for example).
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The
last segment (5th) is very often
longer than the others, it is at the end
of this one
that the telson is. Between the vesicle
and the
5th segment, the anus of the scorpion
is.
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The
legs:
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The
scorpions are Arachnida, they thus have
four pairs of legs, contrary to the Insects
which
have three
pairs of them and to the Crustacea which
have 5 pairs of them.
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Those
are composed of seven segments:
coxa, trochanter, femur, patella,
tibia, basitarsus, and tarsus. With
at the end, a pair of claws is.
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The
legs are used of course for
displacement but also, for the female,
to collect, during the
birth, the pullus which leave the genital
opening (birth basket). They are also very useful to dig,
the shifted
action of the 8 legs also makes it possible
to evacuate
sand or the ground out of the burrow in
construction.
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We
can as notice as the legs are a good
indicator of the medium where the
scorpion saw. Thus, the
species digging of the burrows
have legs shorter than the alive species
in the
rocks. The claws
present at the end of the leg are
much large, robust and hooked for the scorpions
which climb on the
trees or stones, that those alive on sand.
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The
telson:
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The
telson is composed of the vesicle
and the aculeus. Its form, the presence
of hairs (setae)
on the telson, the presence of a tooth under
the aculeus (the subaculear spine), but also
the length
and the curve of the aculeus, can help in the
determination of the species.
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| Bottom of Vaejovis spinigerus male : |
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Coxa:
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The
genital operculum:
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On
the first sternite, is the genital operculum.
It is made of two papillae which according
to their form
indicates the family, the kind or the species
of the
specimen. In some species these papillae
are welded (Scorpionidae) and thus forms
only
one element.. It
is necessary to raise this cover in order
to reach the opening
genital.
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It
is in this opening that one can find the
"copulation hooks"
of the male and thus allow to undoubtedly
distinguish a male from a female. This operation
is alas
very delicate to practise and can be done
only on
dead specimens.
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The
pectines :
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The
pectines (or pecten)
are specific to the scorpions. One finds
them on the ventral face of the abdomen,
on the second sternite, just below the genital
operculum.
They are
two, of sizes and different forms according
to the species and the sex.
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These
organ are chimico-sensory sensors which
inform the scorpion about the ground,
like its composition, its water content
and its temperature. They are mobile organ,
the
scorpion
makes use of it
while scraping, to see in "palpating" surfaces
to be determined.
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The
spiracles
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There
are 8 of them, the two first are hidden by
the pectines.
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They
are the vestiges of the gills when the ancestors
of the scorpion still lived in the sea.
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They
are on the sternites n° 3, 4, 5,
6. These are only small slits that muscles
can open or seal according to the will of
the scorpion.
Behind these slits is the booklungs of the scorpion.
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