Physophora hydrostatica   Forskal,  1775 (Hydrozoan)
Organism information awaits expert curation
Class: Hydrozoa

Image copyrights: Peter Schuchert

Size: Nearly 8.5 cm long, from apex of pneumatophore to tip of palpon.

Nectosome: Well elongated bearing 4-6 pairs of biseria alternately arranged nectophores.

Pneumatophore: 5 mm long; narrow, borne on mobile long stalk, with plum colored pigment at apex; basal pore present.

Nectophore: 1.5 cm X 1 cm with lateral apical corners expanded into wings. Nectosac with sub-angular lateral expansion extending into lateral wings of nectophore; with deep embayment on upper adaxial side and prominent cylindrical neck and ostium. Dorsal and ventral radial canals forming three and two slight loops respectively before joining circular canal. Lateral radial canals highly sinuous; on ventral side running half way upto apical expansion, turning sharply down, taking two long loops, ascending to apical expansion, turning dorsal and downwards again making 3 small loops before joining circular canal. With cleft mouth-plates below large ostium.

Siphosome: Proximal part of protosiphon never elongating to form stem; becoming hypertrophied in horizontal plane to form spiral sac-like basally facetted siphosome-14.5 mm wide. Each facet bearing a cormidium.

Palpons: Characteristic, 26-36 in number long, 22 mm or more in length; at outermost circle. Very active, when alive greenish pink, sessile, attached over a central papilla; heavily armed with nematocysts at tip. With fine long palpacle at base. Palpons bend upward as far as pneumatophore on stimulation (characteristic feature when alive).

Gastrozooids: Smaller than palpons, fewer in number corresponding to number of facets on siphosome, sessile.

Tentacle: Long, bearing many tentilla ending in characteristic cnidosacs. Terminal part of peduncle hypertrophied along side coiled cnidoband; with proximal end becoming distal end. No terminal filament.

Gonodendra: Male and female gonodendra in a whorl between palpons and gastrozooids. Male gonophores at various growth stages, with pedicel, elongated, with well developed umbrella. Female gonophores tiny, ovoid, monovon with reduced umbrella; with peculiar radial canals-four canals, not joining ring canal, link up two and two distally to form 'U' shaped lateral loops. Impressions of 'U' shaped canals formed on ovum make it appear as four eggs.

Bract: Present only in early larval stage -large, dome or umbrella shaped, and dropping off as nectosome elongates. Bracts absent in mature colony.

Synonym (s)
Physophora hydrostatica Forskal, 1775
Physophora hydrostatica Daniel, 1974
Discolabe quadrigata Haeckel, 1888
Discolabe quadrigata Haeckel, 1888
(Junior synonym)

Common Name (s)
Economic Importance and Threats

Habitat:  Pelagic
Predator:  Bony fish (Melanogrammus aeglefinus)


• Bay of Bengal (Lat: 15) (Long: 90) INDIA
• Bay of Bengal (Record: 1962-1965)
• Arabian Sea (Record: 1962-1965)
• Kerala, Off Kochi INDIA (Record: 1962-1965)
• Tamil Nadu, Kanniyakumari INDIA (Record: 1962-1965)
• Andaman and Nicobar Islands, Andaman Islands INDIA (Record: 1962-1965)
• East Coast INDIA (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
  • Zoological Survey of India (Eds) (1991) Animal resources of India (Protozoa to Mammalia) ZSI 1-694 Available at - NCL, Pune
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Sealifebase Available at -
  • The Hydrozoa directory Natural History Museum of Geneva Available at -

Page last updated on:2010-06-23

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