Hydroid colonial on Gastropoda, adult medusa unknown [details]

The gonophores can be released as free swimming medusoids (unpublished observations P. Schuchert). [details]

Likely a synonym of Nemopsis bachei. The species is insufficiently described. [details]

Unrecognisable species, based on a juvenile colony [details]

Calycophorae which develop a temporary larval bract before the larval nectophore, the latter is retained in the ... [details]

Very small, medusoid Hydrozoa without polyp phase, living in the sand interstitial, solitary, bell entirely or very ... [details]

Aequoreidae medusae with numerous, unbranched radial canals; subumbrella without rows of gelatinous ... [details]

Physonectae with a biserial arrangement of nectophores in the nectosome, nectophores on the nectosome are budded ... [details]

Physonectae with one or more nectosomal palpons between each pair of nectophores. Nectophore without ridges, deeply ... [details]

Medusa phase reduced, microscopic, creeping within the interstices of coarse sand sediments; umbrella margin with ... [details]

Medusa with simple mouth lips; four or exceptionally eight simple radial canals; perradial tentacles grouped into ... [details]

Siphonophorae without apical pneumatophore, with a nectosome typically formed by one or two nectophores of ... [details]

Calycophorae in which both anterior and posterior nectophores possess a somatocyst. The nectophores are ... [details]

Campanulariidae with free medusa stage. Hydroid generation forming unbranched stoloniferus or branched upright ... [details]

Mitrocomidae medusae with 4 straight radial canals; 8 open statocysts; no marginal cirri; no ocelli. Note: ... [details]

Narcomedusae with perradial and undivided manubrial pouches, with or without peripheral canal system, with ... [details]

Mitrocomidae medusa with 4 long radial canals, each radial canal curved sharply near circular canal and running ... [details]

Siphonophores with a relatively large pneumatophore and without nectosome; pneumatophore with apical pore; siphosome ... [details]

Calycophorae with usually two dissimilar, streamlined definitive nectophores arranged serially; the anterior ... [details]

Medusa manubrium with narrow base; three, four or more radial canals, radial canals either branched or if not so ... [details]

Mitrocomidae medusa with four radial canals; with numerous open marginal vesicles; without ocelli; without marginal ... [details]

Medusa up to 30 mm wide, umbrella nearly hemispherical, middle portion fairly thick. Velum narrow. Peduncle broad, ... [details]

Medusa manubrium small, usually on rather well differentiated gastric peduncle; 4-6 simple radial canals running ... [details]

Physonectae with uncoiled tentilla bearing a hypertrophied cnidoband. Terminal process devoid of cnidocysts. ... [details]

Hydroid colony sometimes stolonal, but mostly with erect branched stem, arising from a creeping hydrorhiza; stem, ... [details]

Long-stemmed Physonectae, the whole stem (nectosome and siphosome) twisted into a spiral, nectophores thus ... [details]

Trachylinae medusae with gastric peduncle; usually four radial canals, sometimes more; with centripetal canals; ... [details]

Body composed a tubular manubrium with a terminal mouth, on aboral end a small cone separated from manubrium by a ... [details]

Hydroid colony usually erect and branching, rarely stolonal, arising from a creeping hydrorhiza; hydrotheca sessile ... [details]

Trachymedusae with wide, circular manubrium; mouth circular, without distinct lips; without peduncle; without ... [details]

Hydroid colony stolonal or erect branched, hydrotheca campanulate with smooth margin, pedicel present; hydrothecal ... [details]

Calycophorae with biserial arrangement of up to sixteen or more flattened definitive nectophores in varying stages ... [details]

Hydroid colony stolonal or erect, arising from creeping hydrorhiza; hydrotheca tubular to campanulate, radially or ... [details]

Medusa with marginal cordyli, cordyli with or without nematocysts; with or without marginal cirri; with four or ... [details]

Medusa mostly with 4 or 6 complete radial canals, often also with incomplete centripetal canals not reaching ... [details]

Hydroid colonial, stolonal, growing on an underlying sheet of perisarc; hydrothecae sessile or shortly pedicellate, ... [details]

Medusa manubrium short; no gastric peduncle; no excretory pores; four simple radial canals; marginal tentacles ... [details]

Medusa with umbrella lobed, divided by peronial grooves or similar structures; four radial canals; ring canal ... [details]

Medusa with small manubrium; no gastric peduncle; four to eight, sometimes up to 12 radial canals; gonads completely ... [details]

Medusa with broad manubrium base; eight simple or bifurcated radial canals; marginal tentacles hollow; no cirri, no ... [details]

Microscopic hydroids living in biofilms, resembling polyp stage of some Olindiidae, reduced to a spherical or ... [details]

Medusae without gastric peduncle, with open marginal statocysts; with four, eight or more simple radial canals; ... [details]

Hydroid colony stolonal, living on bivalve shells; hydrorhiza creeping reticulated or incrusting or both ... [details]

Hydrozoa without polyp stage or only very reduced and modified polyp stage. Meduse with bell composed of a ... [details]

Medusa with eight simple radial canals; eight normal marginal tentacles and16-32 short, club-shaped tentaculae, ... [details]

Australomedusidae medusae with cruciform manubrium, 4 simple lips, no oral tentacles; 8 radial canals; 8 groups of ... [details]

Medusa 1-30 mm, with or without centripetal canals; internal epi-gastrodermal statocysts; unbranched radial ... [details]

Like Hydractinia, but gonozooids completely or nearly so reduced, sporosacs appearing to arise in clusters from ... [details]

Medusa with very short manubrium on large gastric peduncle; mouth with 8-30 sinuous or crenulated folds; eight or ... [details]

Umbrella much reduced and fused to manubrium so that tentacles and statocysts are arranged around oral end of ... [details]

Trachymedusae with four radial canals; no peduncle and centripetal canals; manubrium well developed; four sac-like ... [details]

Medusa with small small manubrium; no gastric peduncle; four radial canals; gonads on radial canals, separated from ... [details]

Medusa with small manubrium; no peduncle; four simple radial canals; gonads on radial canals, completely surrounding ... [details]

Cystonectae with a horizontal pneumatophore.  [details]

Siphonophorae with an apical pneumatophore and beneath it, a series of nectophores (swimming bells), except in the ... [details]

Physonect siphonophores with a vertical nectosome, nectophores budded off on ventral side of stem, with complexly ... [details]

Hydroid colonies erect, branched or not, stems mono- or polysiphonic; hydrothecae always uniseriate, sessile, and ... [details]

Calycophorae with relatively large and usually rounded nectophores, containing large quantities of mesogloea; the ... [details]

Trachymedusae with either simple manubrium without mesenteries, or with eight-lobed manubrium fixed by eight ... [details]

Laodiceidae medusae with large, prismatic manubrium, 4 radial canals connected to stomach via a large, ... [details]

Physonectae with two forms of tentilla on the same tentacle; the more proximal one with a spirally coiled cnidoband, ... [details]

Cystonectae with an apical, vertical pneumatophore. [details]

Physonectae with nectosome and siphosome contracted to form a globular complex below the enlarged pneumatophore. ... [details]

Trachymedusae with a small manubrium; with or without peduncle; no centripetal canals; usually eight radial canals, ... [details]

Narcomedusae without manubrial pouches; with or without peripheral canal system; gonads develop as thickenings or ... [details]

Calycophorae with a single spherical nectophore of larval origin. [details]

Narcomedusae without bell, worm-like, body divided by groove into aboral and oral halves, along groove four ... [details]

Medusa bell hemispherical to higher than broad, margin not lobed, with ring of thickened tissue studded with ... [details]

Australomedusidae medusae with cruciform manubrium with 4 simple lips; 4 radial canals; 4 groups of marginal ... [details]

[Machine translated and adapted from original source]: Bell diameter 4 -5 mm, umbrella hemispherical, top of the ... [details]

The Mediterranean records for Aselomaris michaeli are likely referrable to A. arenosa. This has to be studied further. [details]

Mediterranean distribution record unpublished? It is quite unlikely for this cold water species to appear in the ... [details]

The Mediterranean records are improbable to erroneous [details]

Species occurs in temperate waters [details]

North-Eastern Atlantic, absent from the North Sea, Baltic Sea,Mediterranean and Black Sea. The northernmost record ... [details]

This species does not occur in the European fauna [details]

This is an arctic species and it is thus very unlikely to be present in the Mediterranean. The Mediterranean record ... [details]

This species has been reported from Lebanon. [details]

This species does not occur in the European fauna, it is an American species [details]

This species does not occur in the European fauna. It is not a dubious species. [details]

This species is not present in the Mediterranean. [details]

The Meditarranean distribution is probably erroneous, as this is an Indo-Pacific species. [details]

This species was originally based on animals observed in European waters, thus all records as an introduced species ... [details]

Mediterranean records are incorrect, Atlantic records refer to M. hargitti. [details]

Distribution of this species in the Mediterranean is unrealistic and quite unlikely for this arctic species [details]

The distribution record of this species in the Mediterranean Sea is probably erroneous [details]

This is a Pacific species, European records could not be found [details]

This species has been reported repeatedly from the Mediterranean by Goy, although in fact this may be another species. [details]

The Mediterranean distribution is unlikely, as the northern limit of this species is France [details]

The European records of this species (Broch) have beel relegated to S. bathyalis. The distribution for S. ... [details]

There are probably no credible records for the Mediterranean [details]

Turritopsis nutricula is likely not present along the European coasts; all well documented cases belong either to ... [details]

The grammatical root for the formation of the family name based on the genus name Orchistoma is "stomat-", not ... [details]

The grammatical root for the formation of the family name based on the genus name Orchistoma is "stomat-", not ... [details]

Name introduced as Thyroscyphus intermedius forma peculiaris Leloup, 1935: 33, figs 15–17. Note that Leloup ... [details]

Name introduced as Sertularella tenella forma peculiaris Leloup, 1935. Note that this is not Sertularella ... [details]

In the original paper describing this species, the name was given as Sigiwedellia bathypelagica in the abstract. ... [details]

This is perhaps a form of Craspedacusta, see Holstein (1995). The generic name Calpasoma is neuter (ICZN Art. ... [details]

The correct family name formation would be Halicreadidae according to § 29.3 of the ICZN. However, as explained ... [details]

The original spelling of Hartlaub was Helgicirrha schulzii, which is a correct formation based on the genitiv of ... [details]