Cnidocytes isolated from the tentacles of Physalia were exclusively either large or small holotrichous isorhizas with dimensions consistent with those reported by Bardi and Marques (2007).
v][beta] previously cloned from the cnidocytes of the tentacles of Physalia physalis is expressed in those cnidocytes, presumably as part of heteromeric voltage-gated [Ca.
Cnidocytes are polarized cells, which in Physalia are grouped into bulbous clusters named cnidosacs.
Table 1 Cnidarian jellyfish species used for feeding experiments of phyllosoma larvae Class Order Species Number of Experiments Scyphozoa* Semaeosiomeae Aurelia aurita > 10 Aurelia aurita > 10 (ephyraev and young medusae) Chrysaora pacifiea > 10 Sanderia malayensis 4 Rhizostomeae Mastigias papua 2 Nemopilema nomurai Hydrozoa Anthomedusae Nemopsis dofleini 4 Spirocodon saltalor > 10 Velella velella 1 Leptomedusae Aequorea S coerulescens Siphonophorae Physalia physafis 1 Cubozoa Cubomedusae Carybdea rastoni 2 * Bell diameters of scyphozoan medusae used for the examinations ranged from 30 to 100 mm.
Interestingly, the phyllosomas had no problems in associating with and feeding on Portuguese man-of-war, Physalia physalis (Fig.
Cnidocil apparatus: sensory receptor of
Physalia nematocytes.
In Chrysaora, Cladonema, Physalia, and Porpita, the staining was particularly dense with the anti-FMRFa antibody.
In the two siphonophore species examined, Porpita and Physalia, the tentacles bear large assemblies of cnidocytes, called cnidosacs, that appear as a line of hemispheres or spheres arranged along one edge of each tentacle.
In Physalia, the cnidosacs are more hemispherical and the ectoderm thinner than Porpita.
Comparison by one of us (JWB) of nematocyst measurements of recent and long-preserved specimens of Chrysaora quinquecirrha and also the hydrozoan
Physalia indicate great variation in measured size due to fixation; sizes given here for C.
Active factors potentially involve the contraction of intracellular cytoskeletal elements, such as has been proposed for cnidocytes of
Physalia (Hessinger and Ford, 1988), and the constriction of adjacent accessory cells, such as the supporting cells that surround cnidocytes in anemone feeding tentacles.
