Melophysa melo   (Quoy & Gaimard,  1824) (Hydrozoan)
Organism information awaits expert curation
Class: Hydrozoa

Size: About 2-2.5 cm long.

Pneumatophore: Ovoid or pear-shaped, with septa containing giant gas-secreting cells, forming a part of secondary ectoderm.

Nectosome (or Nectostyle): Short, reduced with usually one main functional nectophore or rarely with second smaller functional nectophore.

Nectophore: Younger nectophore with long, oblique pedicel and smaller nectosac, 14 mm long, 6 mm broad near expanded region. Lateral sides of pedicel folded to form a groove embracing nectosome. Faintly marked two lateral and one median ridges on dorsal surface. Larger, mature nectophore with shorter pedicel and broader nectosac region 10 mm long; 8 mm broad. Ridges more prominent. Except the ventral radial canal, the dorsal and lateral radial canals sinuous forming loops before joining ring canal. Nectosac ovoid without lateral wings. Ostium dorsal.

Bracts: Diagnostic, thick, gelatinous, borne in 9 or more groups of 3 or 4 bracts each, in a corona below nectosome, on strong muscular lamellae. Larval bracts with smooth dorsal surface, 20 mm long, with prominent keel (11 mm thick) for attachment. Mature bracts similar, with 8-9 strong longitudinal ridges with 25-30 tubercles or conical papillae in each row on dorsal surface.

Gastrozooids: Eight, alternating radially with groups of muscular lamellae of bracts.

Tentacles: Bearing many tentilla, involucrate, tricornuate with 7 or 8 spiral coils in cnidoband.

Palpons: Forming a corona below bracts, long, slender, sessile, 12 mm in length; distal end vermiform, bearing large nematocysts at tip.

Gonodendra: Male and female gonodendra in pairs, alternating with gastrozooids at bases of palpons.

Synonym (s)
Athorybia rosacea Bigelow, 1931
Melophysa melo Daniel, 1974
Rhizophysa melo Quoy & Gaimard, 1827
Rhizophysa melo Quoy and Gaimard, 1824

Common Name (s)
Economic Importance and Threats

Habitat:  Demersal


• Bay of Bengal (Lat: 15) (Long: 90) INDIA
• Bay of Bengal INDIA (Record: 1962-1965)
• Arabian Sea INDIA (Record: 1962-1965)
• Andaman and Nicobar Islands, Andaman Islands INDIA (Record: 1962-1965)
• INDIA (Record: 1962-1965)
• SRI LANKA (Record: 1962-1965)

Literature Source(s)
  • Daniel, R (1985) Fauna of India and the adjacent countries (Coelenterata: Hydrozoa: Siphonophora) ZSI 440 pp Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Sealifebase Available at -
  • 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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