accessory
point Additional small point adjacent to tip of
principal arm (primary branch) of a double
claw.
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adhesive
disc Ventrally adhesive distal section of toe
in certain tardigrades.
anhydrobiosis
Cessation of metabolism initiated by
desiccation of tardigrade. A form of
cryptobiosis.
anoxybiosis
In response to a lack of oxygen, tardigrades
suspend metabolism. A form of
cryptobiosis.
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apophysis
In digestive tract, cuticular thickening at
the junction of buccal tube and pharyrngeal bulb;
functions as a valve.
brain
Main concentration of nerve tissue, composed of
three median lobes and two lateral lobes lying over
pharyngeal bulb and salivary gland.
buccal
tube Section of digestive tract between mouth
and pharyngeal bulb.
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cephalic
papilla In certain tardigrades, one of two
sensory structures located near the mouth;
typically short and broad.
cirrus
(plural is cirri) Cuticular extensions from the
anterior part of the body. Found in armored
heterotardigrades.
cirrus
A In plate bearing tardigrades, long, extension
directed off anterior part of animal.
clavus
Short blunt cuticular projection adjacent and
posterior to base of cirrus A.
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claw
Variously shaped,hook-like structure at distal end
of leg; size, shape, and arrangement are of
taxonomic importance.
cloaca
Term applied to posteriormost section of digestive
tract in those tardigrades in which either oviduct
or vasa deferentia open into rectum.
coelomocyte
Storage cell which is found in fluid-filled
body cavity.
cryobiosis
Form of cryptobiosis that is triggered by a
decrease in temperature. It is an ordered freezing
of cells that preserves life.
cryptobiosis
The suspension of metabolism due to an change
in environment.
cuticle
Noncellular, multilayered, variously ornamented
layer covering outer surface of body and extending
into both foregut and rectum.
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dead
man's float Appearance of tardigrade when in
the anoxybiotic state. It is swollen, motionless,
and all four legs are extended. It is a temporary
state.
double
claw Type of claw which is split into a larger
principal arm and a smaller secondary arm. One or
both of the arms (or branches) can have one or more
points.
esophagus
Tubular section of digestive tract between
pharyngeal bulb and intestine.
external
buccal cirri Pair of sensory externsions, one
on each side of mouth in certain
tardigrades.
eyespot
Pair of dorsal pigmented, light sensitive cells on
anterior end of body.
frontal
plate In plate bearing tardigrade; anteriormost
plate covering greater part of head and bearing
eyespots.
furca
Enlarged posterior end of stylet; typically split
at end.
gonopore
Opening of male or female reproductive system;
opens either at anus or as a separate pore between
third and fourth pair of legs.
internal
buccal cirri Pair of sensory cirri, one on each
side of mouth in armored tardigrades.
lunule
Cutlicular thickening at base of claws in certain
tardigrades, normally half-moon in
shape.
macroplacoid
Large cuticular thickenings in pharyngeal bulb;
shape, number and arrangement are of taxonomic
importance.
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Malpighian
tubule One of three glands, one located
dorsally and two laterally, each consisiting of
three cells. Opens into digestive tract at junction
of intestine and rectum and functions to maintain
internal salt and water balance.
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median
cirrus Terminal median cutlicular extension at
anterior end of head in certain tardigrades; may be
flanked by internal and external buccal cirri as
well as cephalic papillae.
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median
plates 1-3 In plate-bearing tardigrade, small
dorsomedian plates between scapular and first
paired plates, between first and second paired
plates, and between second and psuedosegmental or
terminal plates, respectively.
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microplacoid
In digestive tract, small cuticular thickening
posterior to macroplacoids within pharyngeal bulb;
presence or absence is of taxonomic importance.
(See also macroplacoid)
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midgut
intestine
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mouth
Anterior opening of digestive tract through
which stylets are protruded during feeding;
occasionally surrounded by peribuccal
lamellae.
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ovary
Section of female reproductive system located above
intestine and connected to gonopore via single
oviduct.
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oviduct
Section of female reproductive system leading from
dorsal ovary around right or left side of intestine
to gonopore.
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paired
plates 1, 2 In plate-bearing tardigrade,
large, often spine-bearing, dorsally divided plates
extending down sides of body approximately at level
of second and third leg pairs.
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papillus
Small sensory projection on one or more leg
pairs in certain tardigrades. (See also cephalic
papilla)
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pedal
ganglion Small ganglion in each leg; joined to
central ganglion by nerve.
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peribuccal
lamellae Ring of small cuticular thickenings
surrounding the mouth of certain
tardigrades.
peribuccal
papilla Raised knob-like structures surround
the mouth.
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pharyngeal
bulb (pharynx) Muscular, bulbous section of
digestive tract between the buccal tube and
esophagus, typically with triradiate lumen and
placoids.
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pharyngeal
tube portion (of buccal tube) Section of buccal
tube between stylet supports and pharyngeal
bulb.
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pharynx pharyngeal
bulb
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placoid
General term for variously elaborated, larger
(macroplacoid) or smaller (microplacoid) cuticular
elements within pharyngeal bulb.
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principal
arm In double-claw, larger of two arms. (See
also secondary arm).
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pseudosegmental
plate Additional large plate, with or without
median division, between the third median plate and
the terminal plate in certain
tardigrades
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rectum
(hindgut) Short, cuticle-lined section of
digestive tract between the intestine and anus.
(See also cloaca)
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salivary
gland Pair of large glands, one along each
side of the buccal tube and pharyngeal bulb; opens
anteriorly into buccal tube.
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scapular
plate In plate-bearing tardigrade, large plate
posterior to frontal plate; extends down sides of
body approximately at level of first leg
pair.
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secondary
arm In doubleclaw, smaller of two arms. (See
also principal arm)
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seminal
receptacle Small sac functioning for storage of
sperm in females of certain tardigrades; opens
opposite oviduct into cloaca.
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seminal
vesicle In male reproductive system, expanded
section of sperm duct (vas deferens).
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sperm
duct vas deferens
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spine
Variously elongated (spine, filament) cuticular
projection on leg and/or laterally, dorsolaterally,
and dorsally on posterior margin of
plates.
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spur In
certain tardigrades, small, curved hook, typically
at base of internal claw, occasionally also of
external claw.
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stylet
Pair of lance-shaped cuticular structures, one
on each side of the buccal tube. Pointed anterior
ends project into buccal tube; blunt posterior ends
(furcae) joined to buccal tube by stylet
supports.
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stylet
sheath Pair of sheath-like structures, one on
each side of anterior end of buccal tube; encloses
anterior end of stylet.
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stylet support Pair of
thin, elastic rods joining blunt ends (furcae) of
stylets to buccal tube.
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subpharyngeal
ganglion First of five ventral ganglia; located
below pharyngeal bulb and connected to brain by two
connectives which surround pharyngeal
apparatus.
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terminal
facet Ridge or keel formed by strong downward
angulation of terminal plate.
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terminal
indentation One of two indentations on
posterior margin of terminal plate; imparts plate
with cloverleaf-like appearance.
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terminal
plate In plate-bearing tardigrade,
posteriormost plate; extends down sides of body
approximately at level of last leg pair.
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testis
Section of male reproductive system located
above intestine and connected to gonospore via two
vasa deferentia.
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throttling
Median constriction in macroplacoids in
pharyngeal bulb.
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toe Term
applied to finger-shaped distal projection of legs
bearing terminal adhesive discs; number and
arragnement are of taxonomic importance
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vas
deferens (Sperm duct) Section of male
reproductive system between testis and gonopore;
may be expanded to form seminal vesicle.
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ventral
ganglion One of five ventral concentrations of
nerve tissue (first = subpharyngeal ganglion) along
longitudinal ventral nerve cords.
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ventral
nerve cord Pair of closely adjoining nerve
cords extending from subpharyngeal ganglion to
posterior end of body; bears series of ventral
ganglia, one approximately at level of each leg
pair.
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