Mastigias sidereus, Chun 1896

Systematic position:
Classis Scyphozoa
Subclassis Discomedusae
Ordo Rhizostomeae
Subordo Kolpophorae
Familia Mastigiidae (Stiasny, 1921)
Genus Mastigias (Agassiz, 1862)
Mastigias siderea (Chun, 1896)

Morpho-anatomical characteristics
    Genus Mastigias (Agassiz, 1862):
  • Mouth arms 3-winged, terminating in a naked, club-shaped extremity. With small club-shaped appendages and filaments between the mouths. Mouths located not only along the 3 edges of the mouth arms but also on their flat, expanded sides;
  • 8 rhopalia;
  • A central stomach gives rise to 8 rhopalar canals and numerous interrhopalar canals, all of which anastomose and connect with the ring canal;
  • Exumbrellar sensory pits without furrows;
  • With unitary subgenital cavity.
    Mastigias siderea (Chun, 1896):
  • Bell 70mm wide, flatly rounded;
  • Exumbrella with deep radial furrows on the surface between the lappets;
  • 56-64 marginal lappets;
  • 8 mouth arms as long as bell diameter, upper portion longer than lower portion. with club shaped terminal filaments;
  • 7 radial canals. Intracircular network of canals with large open meshes. Rhopalar canals with anastomoses;
  • Colour of live specimens: bell light yellowish-brown with round white spots, which are largest over the ring-canal and smaller near the margin. 8 blackish streaks along the 8 rhopalar radial-canals on the subumbrella, and also white specks in each octant of the subumbrella between the stomach-pouches and the circular furrow. Mouth arms brown with small white spots. Filaments yellowish.
Life cycle: reproductive strategies unknown.
Geographical and seasonal distribution: South Pacific Ocean. Pelagic species.