Scorpion Morphology Glossary
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- ABDOMEN.-See OPISTHOSOMA.
- ACULEUS.-The
sting or stinger. A hollow, needle-like, terminal spine used for injecting
venom into the prey or would-be predators. A pair of VENOM
DUCTS leads from the VENOM
GLANDS to paired openings near the tip of the ACULEUS. Syn. = STING.
- APOTELE.-See PRETARSUS.
- BASITARSUS.-The
sixth segment of the walking LEG.
It is located on the walking LEG between
the TIBIA and TELOTARSUS.
Pl. = BASITARSI. Syn. = TARSUS or TARSOMERE I.
- BOOK
LUNG.-Paired respiratory organs located in MESOSOMAL
SEGMENTS III-VI. The structures are comprised of numerous thin folds
of cuticle projecting into the body of the scorpion. These thin folds allow
gas exchange between the scorpion's blood and the atmosphere. Together, the
folds look like the pages of a book, hence the term BOOK LUNGS. Each book
is enclosed within a chamber (ATRIUM)
that opens to the atmosphere through a hole (SPIRACLE)
in the MESOSOMAL STERNITE.
Most scorpions have four pairs of BOOK LUNGS. The earliest fossil scorpions
are thought to have had five pairs of BOOK LUNGS. Still other fossil scorpions
may have had only three pairs.
- CARAPACE.-The
large, single sclerite covering the dorsum of the CEPHALOTHORAX or PROSOMA.
- CARINA.-See KEEL.
- CAUDA.-See METASOMA.
- CEPHALOTHORAX.-See PROSOMA.
- CHELA.-A
structure comprised of the TIBIA and TARSUS of
either the CHELICERA or PEDIPALP.
A claw-like structure consisting of a MANUS, FIXED
FINGER, and MOVABLE FINGER.
- CHELICERA.-A
paired, three-segmented appendage arising from PROSOMAL
SEGMENT I (SOMITE III). The
CHELICERAE are modified for feeding and grooming. Pl. = CHELICERAE.
- COXA.-The
first, or proximal-most, segment of a prosomal appendage. It is located on
the CHELICERA before the CHELA,
and on the PEDIPALP and walking LEG before
the TROCHANTER. Pl. = COXAE.
- DACTYL.-The
median claw of the PRETARSUS of
the walking LEG. Syn. = MEDIAN CLAW.
- FEMUR.-The
third segment of the PEDIPALP or
walking LEG. Located on the PEDIPALP or
walking LEG between the TROCHANTER and PATELLA.
Pl. = FEMORA.
- FIXED
FINGER.-The apical extension, or non-articulated finger, of the TIBIA (CHELA)
of either the CHELICERA or
the PEDIPALP.
- FURROW.-Any
of the "valleys" occuring on the integument of the scorpion. These
features are usually associated with internal APODEMES or
ridges that project into the body.
- GENITAL
OPERCULUM.-One of a pair of sclerites located ventrally on MESOSOMAL
SEGMENT I (SOMITE X) that
covers the GENITAL APERTURE of
the scorpion. The sclerites may be completely separated or fused to varying
degrees along the midline. Pl. = GENITAL OPERCULA.
- GENITAL
SEGMENT.-See MESOSOMAL
SEGMENT I.
- HAND.-See MANUS.
- KEEL.-Any
of the "ridges" occuring on the integument of the scorpion. These
features represent structural thickenings of the exoskeleton associated with
stress points. Syn. = CARINA.
- LATERAL
EYES.-A pair of degenerative compound eyes that are located at the anterior
corners of the CARAPACE. Each
LATERAL EYE is typically represented by two to five separate lenses. Syn.
= LATERAL OCELLI.
- LATERAL
OCELLI.-See LATERAL EYES.
- LEG.-Paired,
eight-segmented appendages arising from PROSOMAL
SEGMENTS III-VI (SOMITES V-VIII).
Some workers consider the arachnid leg to be seven-segmented with the BASITARSUS and TELOTARSUS representing TARSOMERES or
pseudosegments, and thus counting as a single segment. The LEGS are
numbered I-IV, anterior to posterior. They are used primarily for locomotion,
but may also be used for digging, mating, or birthing young.
- MANUS.-The
thick, segmental part of the TIBIA (CHELA)
of either the CHELICERA or PEDIPALP.
Syn. = HAND, PALM.
- MAXILLARY
LOBES.-Anterior extensions of the COXAE of LEGS I
and II that form the floor of the PREORAL
CHAMBER. Syn. = COXAPOPHYSIS, ENDITE.
- MEDIAN
CLAW.-See DACTYL.
- MEDIAN
EYES.-A pair of simple, vitreous eyes that are located near the middle
of the CARAPACE.
- MESOSOMA.-The
broad, anterior division of the OPISTHOSOMA corresponding
to SOMITES X-XVI. The MESOSOMAL
SEGMENTS are numbered I-VII, anterior to posterior. Syn. = PREABDOMEN.
- MESOSOMAL
SEGMENT.-One of the segments of the MESOSOMA (SOMITES X-XVI).
The MESOSOMAL SEGMENTS are
numbered I-VII, anterior to posterior.
- MESOSOMAL
SEGMENT I.-The first segment of the MESOSOMA (SOMITE X).
MESOSOMAL SEGMENT I is the GENITAL
SEGMENT. It bears the GENITAL
APERTURE, GENITAL OPERCULA,
and PECTINES ventrally. MESOSOMAL
TERGITE I also corresponds to this segment. Syn. = GENITAL SEGMENT.
- MESOSOMAL
SEGMENT II.-The second segment of the MESOSOMA (SOMITE XI).
MESOSOMAL SEGMENT II is not visible ventrally. Early fossil scorpions exhibited
a STERNITE on this segment. MESOSOMAL
TERGITE II corresponds to this segment dorsally.
- MESOSOMAL
SEGMENT III.-The third segment of the MESOSOMA (SOMITE XII).
This segment is covered by a TERGITE dorsally
and a STERNITE ventrally, however,
some fossil scorpions lacked a STERNITE on
this segment. This segment bears a pair of BOOK
LUNGS.
- MESOSOMAL
SEGMENT IV.-The fourth segment of the MESOSOMA (SOMITE XIII).
This segment is covered by a TERGITE dorsally
and a STERNITE ventrally, and
bears a pair of BOOK LUNGS.
- MESOSOMAL
SEGMENT V.-The fifth segment of the MESOSOMA (SOMITE XIV).
This segment is covered by a TERGITE dorsally
and a STERNITE ventrally, and
bears a pair of BOOK LUNGS.
- MESOSOMAL
SEGMENT VI.-The sixth segment of the MESOSOMA (SOMITE XV).
This segment is covered by a TERGITE dorsally
and a STERNITE ventrally, and
bears a pair of BOOK LUNGS.
- MESOSOMAL
SEGMENT VII.-The seventh segment of the MESOSOMA (SOMITE XV).
This segment is covered by a TERGITE dorsally
and a STERNITE ventrally. This
segment is much longer than the preceding segments and tapers noticeably
to its junction with the METASOMA.
- MESOSOMAL
STERNITE.-Any of the ventral sclerites of MESOSOMAL
SEGMENTS III-VII. The MESOSOMAL STERNITES are numbered III-VII, anterior
to posterior. Syn. = STERNITE.
- MESOSOMAL
TERGITE.-Any of the dorsal sclerites of MESOSOMAL
SEGMENTS I-VII. The MESOSOMAL TERGITES are numbered I-VII, anterior to
posterior. Syn. = TERGITE.
- METASOMA.-The
narrow, posterior division of the OPISTHOSOMA corresponding
to SOMITES XVII-XXI and the TELSON.
The METASOMAL SEGMENTS are
numbered I-V, anterior to posterior. Syn. = CAUDA, POSTABDOMEN.
- METASOMAL
SEGMENT.-Any one of the five segments of the METASOMA.
The METASOMAL SEGMENTS are
numbered I-V, anterior to posterior. The TELSON is
not considered a true segment, but rather a tergal spine of METASOMAL
SEGMENT V.
- METASOMAL
SEGMENT I.-The first segment of the METASOMA.
- METASOMAL
SEGMENT II.-The second segment of the METASOMA.
- METASOMAL
SEGMENT III.-The third segment of the METASOMA.
- METASOMAL
SEGMENT IV.-The fourth segment of the METASOMA.
- METASOMAL
SEGMENT V.-The fifth segment of the METASOMA.
- MOVABLE
FINGER.-The articulated finger of the CHELA of
either the CHELICERA or the PEDIPALP.
The terminal segment of either the CHELICERA or
the PEDIPALP. Syn. = TARSUS.
- OPISTHOSOMA.-The
posterior tagma of the body composed of SOMITES X-XXI.
The OPISTHOSOMA begins with the GENITAL
SEGMENT and includes all POSTGENTIAL
SEGMENTS. In scorpions, the OPISTHOSOMA is divided into a MESOSOMA and
a METASOMA. The OPISTHOSOMA carries
on the functions of respiration, reproduction, and digestion. Syn. = ABDOMEN.
- PALM.-See MANUS.
- PATELLA.-The
fourth segment of the PEDIPALP or
walking LEG. The PATELLA is
located on the PEDIPALP or walking LEG between
the FEMUR and TIBIA.
Pl. = PATELLAE.
- PECTEN.-One
of the paired comb-like appendages located ventrally on MESOSOMAL
SEGMENT I just posterior to the GENITAL
OPERCULA. The PECTINES are
sense organs that contain mechanoreceptors and chemoreceptors. Pl. = PECTINES
or PECTENS.
- PEDIPALP.-Paired,
six-segmented appendages arising from PROSOMAL
SEGMENT II (SOMITE VI). The TIBIA and TARSUS of
the PEDIPALP form a powerful CHELA.
The PEDIPALPS are used in prey
capture, feeding, mating, and defense. They also carry a large number of sensory
receptors.
- POSTABDOMEN.-See METASOMA.
- POSTGENITAL
SEGMENT.-Any body segment posterior to the GENITAL
SEGMENT. Any segment of the OPISTHOSOMA except
for the GENITAL SEGMENT.
- POSTERGITE.-The
portion of the MESOSOMAL
TERGITE posterior to the TRANSVERSE
KEEL.
- POSTTARSUS.-See PRETARSUS.
- PREABDOMEN.-See MESOSOMA.
- PREGENITAL
SEGMENT.-Any body segment anterior to the GENITAL
SEGMENT. Any segment of the PROSOMA.
- PRETARSUS.-The
eighth segment of the walking LEG.
It is located distally on the walking LEG after
the TELOTARSUS. It bears the UNGUES and
the DACTYL. Pl. = PRETARSI. Syn.
= APOTELE or POSTTARSUS.
- PRETERGITE.-The
portion of the MESOSOMAL
TERGITE anterior to the TRANSVERSE
KEEL.
- PROSOMA.-The
anterior tagma of the body comprised of SOMITES I-IX.
The PROSOMA is made up of all
the PREGENITAL SEGMENTS and
includes the "head" (mouth, pharynx, eyes, brain, etc.), CHELICERAE, PEDIPALPS,
and LEGS. The PROSOMA functions
in locomotion, prey capture, feeding, mating, and sensory perception. Syn.
= CEPHALOTHORAX.
- SOMITE.-Any
of the primordial segments of the body. A body segment. Some somites are visible
only at early stages of development, e.g., the clypeolabral and antennal segments
in chelicerates. The SOMITES are numbered I-XXI, from anterior to posterior.
- SPIRACLE.-An
opening in the MESOSOMAL
STERNITE that permits gas to flow between the outside environment and the ATRIUM of
the BOOK LUNG.
- STERNITE.-See MESOSOMAL
STERNITE.
- STERNUM.-A
median sclerite located ventrally on the PROSOMA between
the COXAE of LEGS III
and IV, just anterior to the GENITAL
OPERCULA. The sternum may be formed from remnants of SOMITE IX and may
therefore be homologous with the CHILARIA of xiphosurids and and the metastoma
of eurypterids.
- STING.-See ACULEUS.
- SUBACULEAR
TUBERCLE.-A short spine or denticle sometimes present ventrally at the
base of the ACULEUS. Syn. =
SUBACULEAR TOOTH.
- SUBACULEAR
TOOTH.-See SUBACULEAR
TUBERCLE.
- TARSOMERE
I.-See BASITARSUS.
- TARSOMERE
II.-See TELOTARUS.
- TARSUS.-The
movable, or articulated finger, of the CHELA of
either the CHELICERA or the PEDIPALP.
The terminal segment of either the CHELICERA or
the PEDIPALP. Syn. = MOVABLE
FINGER. Also sometimes refers to the BASITARSUS,
or BASITARSUS and TELOTARUS collectively,
of the walking LEG.
- TELOTARSUS.-The
seventh segment of the walking LEG.
It is located on the walking LEG between
the BASITARSUS and PRETARSUS.
Pl. = TELOTARSI. Syn. = TARSOMERE II.
- TELSON.-A
highly modified tergal spine of METASOMAL
SEGMENT V. It is the posterior-most structure on the scorpion's body. The
TELSON houses the VENOM GLANDS and
bears the ACULEUS.
- TERGITE.-See MESOSOMAL
TERGITE.
- TERMINAL
CLAW.-See UNGUIS.
- TIBIA.-The
fifth segment of the walking LEG,
or the thick, segmental part of the CHELA of
either the CHELICERA or PEDIPALP.
- TRICHOBOTHRIUM.-A
specialized sensory seta designed for detecting vibrations in the air. The TRICHOBOTHRIUM consists
of a cup-like base (the "bothrium") and a long, uniformly thin hair
(the "trich"). TRICHOBOTHIA are found only on the FEMUR, PATELLA,
and TIBIA of the PEDIPALP.
Pl. = TRICHOBOTHRIA.
- TROCHANTER.-The
second segment of the PEDIPALP and
walking LEG It is located between
the COXA and the FEMUR.
- UNGUIS.-One
of the paired submedian claws of the PRETARSUS of
the walking LEG. Pl. = UNGUES. Syn.
= TERMINAL CLAW.
- VENOM
DUCT.-One of the paired, internal tubes leading from the VENOM
GLANDS to the paired openings near the tip of the ACULEUS.
- VENOM
GLAND.-One of the paired, internal sacs found in the VESICLE.
The walls of these organs are lined with glandular tissue that secretes the
various components of the scorpion's venom.
- VESICLE.-The
globular protion of the TELSON anterior
to the ACULEUS. The VESICLE contains
the paired VENOM GLANDS.
- - Dr. Scott Stockwell
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