Order Narcomedusae Haeckel, 1879

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diagnosis

Hydrozoa without polyp stage or only very reduced and modified polyp stage.

Meduse with bell composed of a lens-shaped mass of jelly and much thinner sides, tentacles inserting above bell margin, no tentacular bulbs, bell margin lobed, stomach big, not forming a distinct manubrium, without radial canals; Statocysts almost always external, of endo-ectodermal origin.
Some abberrant forms without bell, wormlike, with four swimming lappets.
No stenoteles. Predominantly forms of the open sea and deeper waters.

higher classification

Cnidaria, Medusozoa, Hydrozoa, Trachylinae

species

about 45

Remarks

The genus Polypodium is sometimes also included in the Narcomedusae. However, this is incorrect and Polypodium is likely not as a member of the Hydrozoa.

characteristics and specific terms

- tentacles originate above umbrella margin

- gastric pouch (one is shaded in blue), not all Narcomedusae have them

- peripheral canal (green), may be absent

- otoporpae (red arrow) are ridges clasping the umbrella margin, formed by a

   thickening of the epidermis, may be absent, function is unknown

- peronia are clefts between the lappets of the umbrella margin(blue arrow)

Classification

Cuninidae Bigelow, 1913

Diagnosis: gastric pouches in phase with tentacles, same number of tentacles and pouches.

Narcomedusae with perradial and undivided stomach pouches; with or without peripheral canal system; with tentacles leaving umbrella opposite centre of each stomach pouch, equal in number to that of pouches; pouches not extending towards periphery not beyond the points of origin of tentacles; without secondary tentacles on umbrella margin; with or without otoporpae.

Aeginidae Gegenbaur, 1857

Diagnosis:  gastric pouches between tentacles, number of pouches larger than number of tentacles.

Narcomedusae with interradial, divided stomach pouches bearing the gonads; with or without peripheral canal system; with primary tentacles leaving umbrella between marginal pouches; pouches extending towards periphery beyond points of origin of primary tentacles; with or without secondary tentacles on umbrella margin; with or without otoporpae.

Solmarisidae Haeckel, 1879

Diagnosis: without gastric pouches.

Narcomedusae without manubrial pouches; with or without peripheral canal system; gonads develop as thickenings or diverticulae in the oral wall of the central stomach;  with numerous tentacles leaving exumbrella at level of periphery of stomach; with or without otoporpae.

Tetraplatidae

Diagnosis: wormlike, no bell

Narcomedusae without bell, worm-like, body divided by groove into aboral and oral halves, along groove four marginal lappets used for swimming. Aboral and oral portion of body mayor may not be connected by four flying buttresses alternating with marginal lappets. Eight sense organs in marginal lappets. No tentacles. Four epidermal gonads each with paired aboral and oral lobes.

References

Bouillon, J. 1987. Considérations sur le dévéloppement des narcoméduses et sur leur position phylogénétique. Indo Malayan Zoology 4: 189-278.

Collins, A. G., Bentlage, B., Matsumoto, G. I., Haddock, S. H. D., Osborn, K. J., & Schierwater, B. 2005. Solution to the phylogenetic enigma of Tetraplatia, a worm-shaped cnidarian. Biology Letters online publication

Kramp, P. L. 1959a. The Hydromedusae of the Atlantic Ocean and adjacent waters. Dana Report 46: 1-283.

Russell, F. S. 1953.The medusae of the British Isles. Cambridge University Press, London,  pp.  530, 35 pls.