Familia Mastigiidae (Stiasny, 1921)
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.
reproductive strategies unknown.
Geographical and seasonal distribution:
South Pacific Ocean. Pelagic species.