Rosacea plicata   Bigelow,  1911 (Hydrozoan)
Organism information awaits expert curation
Class: Hydrozoa

Polygastric phase: A pair of large smooth, round to oval nectophores of equal size. Nectophores develop from reserve bells after the larval ones fall off. Larval nectophores caducous, up to 12 mm in length; definitive nectophores measure up to 32 mm in length.

Larval nectophore: Caducous, small with short circumscribed, slit-like hydroecial opening. Pallial canal (part of somatocyst) bent sharply round central organ. Lateral radial canals with sigmoid course.

Definitive nectophores: Bigger, elongated, 21-32 mm long; hydroecium deeply conical; with deep pocket for attachment of muscular lamella. Somatocyst thin, thread like lying close to dorsal wall of hydroecium bent at apex of hydroecium, extending down beyond pedicular canal. Lateral radial canals longer, with meandering course, before joining circular canal. Dorsal and ventral radial canals, shorter, simple straight. Opening of hydroecium not extending entire length.

Eudoxid phase: Bract globular, smooth, 18 mm in diameter, 3 lobed; with 6 bracteal canals - dorsal, ventral, two spur canals, left and right hydroecial canals. Bracteal cavity or hydroecium conical bounded by three lobes of bract. Right hydroecial canal longer than left. Spur canals very short; dorsal canal reaches upto dorsal surface of bract. Central organ present. Gonophores bear male or female germ cells upon short manubrium. Radial canals simple, straight and join circular canal. No tubercles, pigment spots or tentacles present around mouth of nectosac.

Synonym (s)
Rosacea plicata Daniel, 1974
Rosacea plicata Bigelow, 1911
Neorosacea bigelowi (Margulis, 1994)
Neorosacea plicata (Quoy & Gaimard, 1833)

Common Name (s)
Economic Importance and Threats

Habitat:  Pelagic, Coastal


• Andaman and Nicobar Islands, Andaman Islands INDIA (Record: 1962-1965)
• INDIA (Record: 1962-1965)
• Arabian Sea INDIA (Record: 1962-1965)
• Bay of Bengal INDIA (Record: 1962-1965)
• Lakshadweep Sea INDIA
• West Coast INDIA

Literature Source(s)
  • Daniel, R (1985) Fauna of India and the adjacent countries (Coelenterata: Hydrozoa: Siphonophora) ZSI 440 pp Available at - NIO, Goa
  • Daniel, R and Daniel, A (1969) Siphonophora collected during the 35th cruise of the R. V. VITYAZ in the eastern part of the Indian Ocean Symposium on Indian Ocean, Part II 571-574 Available at - Library, CAS, Parangipettai
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Sealifebase Available at -
  • Rengarajan, K (1975) Distribution of siphonophores along the west coast of India and the Laccadive sea Journal of the marine biological association of India The marine biological association of India 17(1) 56-72 Available at - NIO, Goa
  • Boltovskoy, D (Ed.) Zooplankton of the South Atlantic Ocean Marine Species Identification Portal Available at -

Page last updated on:2011-09-09

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