Abdomen segmented hindmost part of the body flexed forward under thorax consisting of six somites
 Abdominal somite any single division of body behind thorax; syn.,pleomere, pleonite
Aereolated bronzy
Afferent branchial channels openings through which water passes to branchiae, usually situated in front of chelipeds and behind pterygostomian regions, except in some of Oxystomata, where they open anteriorly, at sides of endostome
Afferent channels openings through which water passes to gills, in brachyuran crabs generally located in front of bases of chelipeds
Ambulatory capable of walking
Antennae or 2nd pair of antennae second pair of appendages situated between antennules and orbits

Antennal flagellum narrow terminal part of the 2nd antenna composed of several segments

Antennal peduncle five basal segments of 2nd antenna; firstsegment usually fused to epistome, second and third segments fused together

Antennal spine a spine on frontal margin of carapace dorsal to antennae

Antennules or 1st pair of first pair of appendages situated closeantennae together under front on either side of median line
Antennular pits cavities into which antennules may be folded

Antero-lateral margin antero-lateral border of carapace

Antero-lateral teeth teeth on antero-lateral margin, postorbital tooth included
Antero-orbital spine

spine at postero-lateral corner of supraorbital eave

Arm merus of cheliped

Gill of decapods attached to articular membrane between limb and body; syn., arthrobranchia

Basal antennal article fused second and third segments of 2nd antennae

second segment of a pereiopod or maxilliped counted from body, or sixth segment counted from distal end, immovably united with ischium


two-branched; crustacean limb in which basis bears both exopod and endopod

Branchial region

large paired lateral areas on carapace behind cervical groove

Buccal cavern

cavity or area on ventral surface of body in which mouth parts situated, bounded anteriorly by epistome, laterally by pterygostomian regions and posteriorly by thoracic sternum

Buccal cavity or mouth-field

cavity or area on ventral surface of body in which mouth parts situated, bounded anteriorly by epistome, laterally by pterygostomian regions and posteriorly by thoracic sternum

Buccal frame

structure of brachyuran decapods enclosing mouth parts,its sides formed by free anterolateral edges of carapace,its front delimited by epistome, and commonly closed by operculiform third maxillipeds


a round polished tubercle of a greyish-white colour on thoracic sternum immediately in front of apex or abdomen


exoskeleton which covers dorsal surface behind

cervical groove

Carapace carina

Narrow ridge variously located on surface of decapod carapace - named types:

  • Antennal carina : narrow ridge extending backward from antennal spine.
  • Branchial carina : narrow ridge extending backward from orbita over branchial region.
  • Branchio-cardiac carina : narrow ridge making off branchial from cardiac regions of carapace.
  • Gastro-orbital carina : narrow ridge extending backward from supra-orbital spine.
  • Lateral carina : narrow ridge on side margin of carapace.
  • Orbital carina : narrow ridge on margin of orbit.
  • Posterior carina : transverse narrow ridge in front of carapace marginal groove.
  • Postorbital carina : narrow ridge slightly behind orbital marign and parallel to it.
  • Postrostral carina : narrow ridge behind rostrum extending along dorsal mid-line of carapace.
  • Rostral carina : longitudinal narrow ridge continuous with lateral margin of rostrum.
  • Subhepatic carina : narrow ridge extending backwar from branchiostegal spine.
  • Submedian carina : narrow ridge on either side of postrostral carina and parallel to it; may join rosstral carina.
  • Supraorbital carina : See gastroorbital carina.


Carapace costae

closely spaced radial ridges, grading from fine to coarse, that become obsolete near umbo and do not cross it (=radial lirae, radial riblets, accessory ribs)

Carapace groove furrow on surface of decapod, generally dorsal - named types:
  • Antennal groove : furrow on carapace extending backward from vicinity of antennal spine.
  • Brachiocardiac groove : Oblique furrow approximately in middle of posterior half of each side of carapace, separating branchial and cardiac regions andreaching dorsomedian part ofcarapace well behind cervical or postcervical grooves; maybe longitudinal, connecting cervical and postcervicalgrooves, of extending backward from submedian point on postcervical grooves,or extending backward from submedian point on postcervical groove.
  • Cervical groove : Transverse furrow in median part of carapace between gastric and cardiac regions, curving forward toward antennal spine.
  • Gastro-orbital groove : short longitudinal furrow branching from cervical groove at level of orbit and running toward it.
  • Hepatic groove : Short longitudinal furrow connecting cervical with postcervical and branchiocardiac grooves, more or lesscontinuing antennal groove.
  • Inferior groove : transverse furrow extending from junction or hepatic and cervical grooves toward side margin of carapace, more or less continuous with cervical groove.
  • Marginal groove : furrow close to posterior edge of carapace and parallel to it.
  • Postcephalic groove : one of three transverse furrows on carapace of many fossil decapods.
  • Postcervical groove : furrow located behind cervical groove and parallelto it, dividing cardiae region into two parts.
  • Submedian groove : longitudinal furrow in submedian dorsal part of carapace closely adjacent to postrostral carina.

Cardiac region

median area on carapace behind cervical groove

Cardiac region or area differentiated portion of decapod carapace surface distinguished in descriptions and used in classification - named types:
  • Antennal region : anterior marginal part of carapace bordering orbital region laterally and also touching hepatic, pterygostomial, and, in some forms, frontal region.
  • Anterolateral region : anterior marginal part of carapace bordering subhepatic or hepatic regions.
  • Branchial region : lateral part of carapace behind pterygostomial region and overlying branchiae, divided by some authors into epibranchial, mesobranchial, and metabranchial subregions.
  • Cardiae region : median part of carapace behind cervical groove or suture, between urogastric and intestinal areas.
  • Frontal region : anteromedian part of carapace including rostrum and area behind it
  • Gastric region : median part of carapace in front of cervical groove and behind frontalregion; divided by some authors into epigastirc, mesogastric, metagastric, proto-gastric, and urogastric subregions.
  • Hepatic region : part of carapace which may touch antennal, cardiac, and pterygostomial regions.
  • Intestinal region : short transverse part of carapace behind cardiac region, designated by some as posterior cardiac lobe.
  • Jugal region : See pterygostomial region.
  • Orbital region : part of carapace behind eyes, bordered by frontal and antennal regions.
  • Pterygostomial region : anterolateral part of carapaceon ventral surface located on opposite sides of buccal cavity .
  • Subhepatic region : part of carapace below hepatic region and extending below lateral edge of latter.

Carapace spine

sharp projection of carapace important for classification - chief types:

  • Antennal spine : spine on front margin of carapaceslightly below orbit.
  • Branchiostegal spine : Spine on front margin of carapace or slightly behind it about halfway between antennal and pterygostomial spines.
  • Hepatic spine : spine in hepatic region of carapace below lower branch of cervical groove and behind it.
  • Infraorbital spine : Spine on lower angle of orbit.
  • Postorbital spine : spine at moderate distance behind middle of orbit.
  • Postrostral : Dorsomedian spine immediately behind rostrum.
  • Pterygostomial spine : Spine on anterolateral angle of carapace.
  • Suborbital spine : spine at moderate distance below middle of orbit and slightly beneath it.
  • Superorbital spine : Spine at moderate distance obliquely behind and above orbit (may be placed on postorbital carina).
Carpace tooth

small sharp spinous projection in varied locations - named types:

  • Cardiac tooth : tooth on mid-line of carapace just behind cervical goove.
  • Gastric tooth : tooth on mid-line of carapace just in front of cervical goove.
  • Lateral tooth : tooth placed on lateral margin of carapace (includes anterolateral, mediolateral, posterolateral teeth).
  • Orbital tooth : tooth on orbital margin.
  • Posterior tooth : tooth on mid-line of carapace just in front of posterior margin between it and marginal groove.
  • Pregastric tooth : tooth on mid-line of carapace between gastric tooth and rostrum.
  • Rostral tooth : on rostrum; may be single or multiple and classified as upper, lower, or lateral
  • Carinated : keeled

fifth segment of a pereiopod or maxilliped, counted from body, or third segment counted from distal end

Cephalothorax fused head and thorax
Cervical groove complex groove running across dorsal surface of carapace,being transverse at middle and turning obliquely forward on each side to lateral margins, it separates hepatic and gastric regions from branchial and cardiac regions
Chela, claw or hand two last segments of a cheliped, dactylus being movable finger
Cheliped first pair of pereiopods or ninth pair of appendages, usually stouter than other pereiopods, two last segments forming a claw
Clypeiform shield like expansion
Concealing from being seen or known about
Coxa first segment of a pereiopod or maxilliped, counted from body
Crenated having a notched or scalloped edge
Cressorial adapted for walking
Cristiform crested / a ridge or fold resembling a crest
Dactylus seventh or terminal segment of a pereiopod or maxilliped, counted from body
Deflexed turn from its direction of movement
Dentiform having a shape of teeth
Dilated expanded and flattened
Discoid circular
Distal direction away from central part of body; opposite of proximal
Downy a soft covering of fluffy hair
Efferent branchial channels channels through which water passes from branchiae, they open at sides of endostome except in Oxystomata where they open at middle of endostome
Elliptical regular oval
Emarginate having a margin that in notched or slightly forked
Endognath endopod (inner and principal branch) of maxilliped
Endopod or endopodite inner branch of a biramous body appendage
Endoskeleton Internal hard parts of some decapods consisting mainly of endophragms
Endostome skeletal area posterior to epistome forming roof of buccal cavity
Epibranchial lobe or area anterior part of branchial region of decapod carapace
Epigastric lobe or area anterior entension of gastric region of decapod (brachyuran) carapace
Enstomial canal comb form meaning a 'sword'
Epistome transverse plate forming anterior border of buccal cavity; lateral sides fused with carapace; mid-anteriorly plate extends forward in a slender process, which is usually fused with front
Eve decline or end
Excretory glands open on first segment of antennae
Exognath outside or beyond exoskeleton
Exopod or Exopodite outer branch of a biramous body appendage, suppressed in all pereiopods
Exoskeleton entire horny (in part chitinous) more or less calcified outer covering of crustacean body and its appendages
Eyestalks peduncle movably articulated with head, carrying eye at its distal extremity, may be divided into 2 or 3 segments and may be retractable; syn., ocular peduncle
Filiform thread like / strung on a thread
Fingers scissor-like part of claw of chelipeds, movable finger being dactylus, immovable or fixed finger, being terminal part of propodus
Flagellum (pl., flagella) slender, multiarticulate distal part of antennule, antenna or exopod
Fossets pipe like structure
Front Part of crab carapace between orbits
Front of frontal region foremost median area on carapace between orbital regions
Frontal teeth

teeth on frontal margin exclusive of inner orbital teeth

Gastric region large median area on carapace anterior to cervical groove, divisible into several subregions, bounded laterally by hepatic regions, anteriorly by front and orbital regions
Gressorial walking
Glossy smooth and shining, high by polished
Hand see chela
Hepatic region small antero-lateral area on carapace anterior to branchial regions
Inner suborbital tooth see infraorbital lobe
Infraorbital lobe, spine or tooth innermost lobe, spine or tooth on ventral margin or orbit
Inner orbital tooth innermost tooth on dorsal margin of orbit
Interantennular septum plate which separates two antennular cavities from each other, formed by union of a slender anterior process of the epistome and front
Interantennular spine a median downgrowth of front on anterior part of interantennular septum
Intercalary spine a spine on dorsal margin of orbit lying between postorbital spine and supraorbital eave
Intestinal region small hindmost median area on carapace behind cardiac region
Ischium third segment of a pereiopod or maxilliped, counted from body, or fifth segment counted from distal end
Jagged habitual intoxication
Knee point of most pronounced flexure of endopod
Lateral margin differentiated edge of carapace in some advanced macrurans and many brachyurans
Linea homolica a groove running from behind and forward on either side of carapace
Lobe any blunt prominent arising from a surface
Lobulated having a lobe or lobulated
Lumpy protuberance / swelling
Mandible third pair of appendages, or first pair of mouth parts
Manus or palm proximal part of propodus of cheliped
Maxillipeds sixth to eighth pair of appendages, fourth to sixth or three posteriormost pairs of mouth parts
Maxillae fourth and fifth pair of appendages, or second and third pairs of mouth parts
Merus fourth segment of a pereiopod or maxilliped counted from body, and also fourth segment counted from distal end
Mesocerebrum ganglion of antennular somite; syn., deuterocerebrum
Mesosome colletive term for all free thoracic somites behind head
Mesosternum median plate arising from sternum in many brachyurans
Metabranchial lobe or area posterior part of branchial region of decapod (brachyuran) carapace; may be ill-defined or undifferentiated
Mouth-field see buccal cavity
Movable finger dactylus of chela
Natatory adapted or used for swimming
Nodose having nodes, knots or swelling
Nodular occurring in form of small rounded lumps
Orbit eye cavities
Orbital hiatus gap in ventral margin of orbital at itsinner angle
Orbital region narrow area bordering dorsal margin of orbit ; not always distinguishable
Oblique not horizontal or vertical, sloping, slanting
Olfactory hair Sensory seta covered by delicate cuticle projecting from most antennules and antennae; syn., aesthetasc, esthetasc, aesthetem, esthete
Ommatidium (pl. ommatidia) Cylindrical or prismoidal visual constituent of compound eye covered by transparent cuticle (cornea)
Oval shaped like an egg
Palm see manus
Palm three inches, a planter surface
Palpus or palp distal two or three segments of maxillipeds following merus
Paxilliform An osculatory, truce, peace
Pearly like pearl
Pectinated a comb like structure
Penicillus (pl., penicilli) Tuft of fine hairs resembling small brush
Penultimate segment next to and before last one
Pereiopods ninth to thirteenth pair of appendages, or chelipeds and four pairs of walking legs
Pleopods fourteenth to eighteenth pair of appendages on first to fifth abdominal somites
Pleural suture linc of splitting apart of carpace in molting, corresponding to linea dromica, and present in all brachyurans
Pleurobranch Gill of decapods attached directly to body wall syn., pleurobranchia
Podophthalmite one of 2 segments of eyestalk, articulating with basophthalmite proximally and bearing corneal surface of eye distally
Postero-lateral margin postero-lateral border of carapace
Postocular behind
Postorbital spine or tooth outermost or hindmost spine or tooth on orbital margin also referred to as first antero-lateral tooth
Pouch area of baggy loose skin
Prehensile to grasp and hold things
Preorbital spine a spine on anterior part of supraorbital eave (when eave is developed in its most prominent form
Propodus sixth segment of a pereiopod or maxilliped, counted from body, or second segment counted
Protocerebrum ganglion of first (preantennulary) somite
Protogastric lobe or area anterolateral division of gastric region of decapod (brachyuran) carapce
Protuberance bulge or swelling
Proximal Direction toward center of body; opposite of distal
Pterygostomian region area on ventral surface of the carapace on either side of buccal cavity
Pubescent hairy
Punctate dotted

pear shaped

Quadridentate having four parts
Quadrilateral four sided, a group of four fortresses, a plane figure bounded by four straight lines
Ramose branched
Repose calm / settled
Rhomboidal like a rhombus/nearly square with petiole at one of acute angles
Rhomboidal gap lozenge-shaped or whirling (four sided figure in shape of diamond)
Rostrum a median outgrowth anteriorly on carapace forming a single or two distinct spines or horns
Rugose wrinkled, covered with sunken lines
Sausage length of an object
Scabrous rough with projecting points
Segment separate rings of appendages
Serration irregular saw-toothed outline on dorsal edges of some conchostracan valves where growth bands do not end on same hinge line; may have various expression from strongly serrate to subdued serrate and pseudoserrate
Seta (pl., setae) hairlike process of cuticle with which it is articulate
Sinuate bent / having a wavy edge or margin
Somite Division of body (head, thorax, abdomen) with exoskeleton comprising body-ring that is generally divisible into dorsal (tergite) and ventral (sternite) portions
Somite a body segment
Squamiform like a scale
Squarish approximately square
Statocyst a balance organ lying in basal segment of antennules
Stomodeum anterior part of alimentary tract, ectodermal in origin and lined with cuticle continuous with mouth; includes esophagus and dilated part corresponding to stomach, and may contain so-called gastric mull of varying complexity for trituration of food; syn., foregut; stomodaeum
Stridulating organ structure in which two parts of exoskeleton are rubbed together in order to produce sound, one part consisting of ridge of tuberculate or cross-ridged surface which is apposed to another part usually having single transverse ridge or tubercle
Stylocerite rounded or spiniform process on outer part of proximal segment of antennular peduncle in some decapod syn., antennular scale
Subacute slightly or moderately severe
Subbranchial region paired areas on ventral surface of carapace, below branchial regions
Subglobose slightly or moderately globose
Subhepatic region paired area on ventral surface below hepatic regions
Sublaminar slightly or moderately plate like / leaf like
Suborbital region narrow area bordering ventral margin of orbit
Supraorbital eave lateral part of orbital region above eye-stalks projecting laterally to form an eave
Supraorbital spine single spine on supraorbital eave, when eave is a very narrow structure leaving eye-stalk completely visible in dorsal view
Telson unpaired appendix on hindmost abdominal somite
Thoracic sternum ventral, segmented wall of thorax with all sternites fused
Thorax seventh to fourteenth somites, in Brachyura always fused with six head somites
Tricuspid having three cusps or points as a tooth
Trigonous triangular in section
Tubercliform tube shaped
Urinal article opening of excretory organ, situated on first segment of antennae
Uropod last pair of abdominal appendages on sixth abdominal somite, almost always lacking in adult Brachyura few species having vestiges of uropods
Walking legs second to fifth pereiopods
Wart a protuberant growth which occurs singly or in groups on skin surface

carpus of cheliped, joint on which hand moves`