The Hydrozoa: a new classification in the light of old knowledge

The Hydrozoa, on the basis of embryological, developmental and morphological features, are considered as a superclass of the phylum Cnidaria comprising three classes: the Automedusa (with the subclasses: Actinulidae, Narcomedusae and Trachymedusae), characterised by direct development of the planula into a medusa; the Hydroidomedusa (with the subclasses: Anthomedusae, Laingiomedusae, Leptomedusae, Limnomedusae, and Siphonophorae), characterised by a polyp stage budding medusae through a medusary nodule; and the Polypodiozoa, with complex endocellular parasitic life cycles

Remarques sur des Cnidaires du type de <i>Microhydrula pontica</i> Valkanov 1965, trouvés à Roscoff

Two different forms of a small Cnidaria extremely reduced in his organisation and corresponding to the Hydrozoa Microhydrula pontica Valkanov 1965 are found during the whole year in the region of Roscoff on biological substratums which are developping at the surface in prolongated contact with the water. These two forms are distinguished by some histological characters, but especially by the cnidom. Each form has only one type of cnidocysts. The form which remains in the genus and species Microhydrula pontica has classical eurytelian microbasic cnidocysts; the other has a partiular type of cnidocysts, which have been described as 'semiophors'. The basal part is of the eurythelian microbasic type, but the filament is subdivided in two portions, separated by a elbow having a special spine as ornement. The genus and the species Rhaptapagis cantacuzenei n.g., n.sp. Are proposed for this form and the family of the Microhydrulidae has for the moment these two genus

Heterochrony, generic distinction and phylogeny in the family Hydractiniidae (Hydrozoa, Cnidaria)

The taxonomy of Hydractinia, Stylactaria and Podocoryna is discussed and the three genera are merged into Hydractinia since their diagnostic characters are liable to lead to polyphyly and paraphyly, due to repeated episodes of medusa reduction via heterochrony (paedomorphosis). The phylogeny of the Hydractiniidae is reconstructed by using two outgroups, Clava and Cytaeis, both having some characters in common with the Hydractiniidae. The resulting phylogenetic trees agree in identifying affinities among Hydractinia, Kinetocodium and Hydrocorella, all with polymorphic colonies with gastrozooids having oral tentacles. The position of Clavactinia (characterized by gastrozooids with widely scattered tentacles) is at the root of the tree if Clava is the outgroup, whereas it becomes apical when the outgroup is Cytaeis. The pattern of medusa suppression is different in the two cladograms, since the presence of a medusa is a plesiomorphic feature when Cytaeis is the outgroup, whereas it becomes apomorphic when the outgroup is Clava. These inconveniences are difficult to accommodate, since medusa suppression has occurred many times in the evolution of the hydroidomedusae, and Recent species do not witness past paedomorphic events of medusa reduction properly, so that many intermediate states are probably missing

Etude des Solanderiidae de la Baie de Hansa (Papouasie Nouvelle-Guinée) avec une révision du genre <i>Solanderia</i> (Cnidaria, Hydrozoa)

The morphology of the skeleton of the various species of the genus Solandria was studied by scanning electron microscopy. This allowed the listing of synonymies, and the number of valid species was reduced from 13 to 6. Keys and a comparison table have been established for species identification

Wirkortäquilibration, Anschlagzeit, "time to peak effect": Bedeutung pharmakokinetisch-dynamischer Prinzipien für die tägliche klinische Praxis

Zusammenfassung: In der anästhesiologischen Pharmakologie spielen im Gegensatz zur internistischen Pharmakologie "Non-steady-state-Phänomene" eine herausragende Rolle. Ihr Verständnis ist eine Conditio sine qua non für die sichere und effiziente Applikation von anästhesierelevanten Medikamenten. Insbesondere die Verfügbarkeit der "optimierten target controlled infusion" ("optimized TCI"), von TCI-Systemen mit Ansteuerung des Effektkompartiments und dem relativ geringen Dosierungsspielraum bei "conscious sedation" unter erhaltener Spontanatmung verlangen von Anästhesisten, sich mit dem Konzept des Konzentrationsverlaufes am Wirkort auseinander zu setzen. Der Leser wird in die grundlegende Problematik eingeführt. Anwendungen der Prinzipien bei der Applikation von Muskelrelaxanzien, Propofol mit TCI-Systemen, volatilen Anästhetika und Opiaten werden erläuter

Photosynthetic planulae and planktonic hydroids: contrasting strategies of propagule survival

Settlement delays can be important to prevent propagule waste when proper settling substrates are not immediately available. Under laboratory conditions, the planulae of Clytia viridicans underwent two alternative developmental patterns. Some settled on the bottom, forming a hydranth-gonotheca complex that produced up to four medusae and later either degenerated or gave rise to a hydroid colony. Other planulae settled right below the air-water interface, forming floating colonies that eventually fell to the bottom and settled. Halecium nanum released planulae with a rich population of symbiotic zooxanthellae that survived into a rearing jar for three months. After a long period of apparent quiescence (possibly fuelled by photosynthetic activities of zooxanthellae) the planulae produced new colonies. Both photosynthetic planulae and settlement at the interface air-water allow a delay in the passage from a planktonic to a fully functional benthic life

On the origins and evolution of hydromedusan life cycles (Cnidaria, Hydrozoa).

Selected Symposia and Monographs U.Z.I., 6