Ordre Résumé for Rajiformes

  Réf. Princ.
:
  Ordre
:
Rajiformes skates and rays
  Classe
:
Elasmobranchii
  Ordre frère
:
Torpediniformes 50 M years
  Réf..
:
  Premier signalement fossile
:
early Tertiary
  Présent dans
:
Marin
Eau douce
Saumâtre
  Remarque
:
Gill openings ventral; anterior edge of the greatly enlarged pectoral fin attached to side of head, anterior to the gill openings; anal fin absent; eyes and spiracles on dorsal surface; anterior vertebrae fused to form a synarcual; suprascapulae of pectoral girdles joined dorsally over vertebral column and articulating with column of synarcual or fused with synarcual; nictitating membrane absent, cornea attached directly to skin around the eyes; body generally strongly depressed; jaws protrusible in most; teeth pavementlike; in most, water for breathing taken in chiefly through the spiracle rather than the mouth (except for those living off the bottom); most give birth to live young (some have eggs encased in a horny capsule); the snout may function as an electroreceptive organ (as may be true for all elasmobranchs).
  ClasseÉtymologie
:
Greek eulanein, elasmos = metal beaten out + Greek brangchia = gills. Ref. 45335.
  OrdreÉtymologie
:
Latin, raja = ray + Latin, forma = shape (Ref. 45335).
  Familles
:

Ref.
[ e.g. 9948]                       
Glossary
                    [ e.g. cephalopods]

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