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A. Agassiz, 1863

Description
Umbrella watch-glass shaped, when at rest about four times as broad as high; jelly fairly thick, especially toward centre. Velum fairly narrow, ca. 1/8 bell radius. [H.ocellata-habitus ]
Stomach short, broad and flat, about 1/5 diameter of umbrella, circular to irregular star-shaped in outline with well-developed funnels; dorsal wall attached to subumbrella along continuations of radial canals leaving numerous triangular pouches between subumbrella and wall of stomach. Mouth with four folded lips [H.ocellata-medusa1 ].
Radial canals 11-17, usually 12-16; these and ring canal narrow. Radial canals originating centrally as four, each dividing into three or four branches, the branching usually occurring within outline of stomach [H.ocellata-medusa2 ].
Gonads linear, forming narrow somewhat folded bands along 2/3 of each radial canal somewhat or much nearer ring canal than stomach; situated on side walls of canals with median furrows in both sexes [H.ocellata-medusa2 ].
Marginal tentacles up to at least 450, with broad conical bases [H.ocellata-medusa1 ]. Usually one spirally coiled marginal cirrus between adjacent tentacles [H.ocellata-margin]. Usually 5-6 large open marginal vesicles between every two radial canals making about 80 in all, with large number of concretions.

Size
Diameter of umbrella at maturity usually 60-70 mm, though specimens up to 150 mm recorded; stomach diameter recorded as 0.13-0.31 times that of bell; length of marginal tentacles 0.3-0.5 times bell diameter; velum 2.5-3.0 mm wide, gonads commencing 2-7 mm from edge of stomach and ending 1-2 mm from ring canal (Kramp, 1920).

Colour
Whole medusa faint rose-red, gonads greyish, pinkish or white (pink in preserved specimens).

Ecology
British plankton records of medusa May-August.

Depth range and distribution around the British Isles
(After Russell, 1953a) Probably occurs in deep or oceanic water where this comes near to the coast. Recorded only well offshore on Atlantic coasts, off mouth of English Channel, W and SW Ireland, N and W Scotland. Most records in Faeroese waters and the Faeroe-Shetland Channel (J. H. Fraser, 1972).

Distribution in the North Sea
Northern North Sea, over deep water.

World distribution
Mainly Atlantic Ocean; recorded off Denmark, S Iceland, Faeroe-Shetland Channel, Norwegian Sea, whole Norwegian coast, (Russell, 1953a; Kramp, 1961) and the Barents Sea (Naumov, 1969). In the NW Atlantic, recorded from W Greenland and from Grand Manan to Cape Cod. Also reported from the Falkland Islands.

Remark
Hydroid unknown.

[Description after Cornelius, 1995a]

Halopsis ocellata