The purpose of this study was to characterize the mode of action of nematocyst venom from the Portuguese man-of-war (Physalia physalis) on isolated rabbit arterial ring segments, and to see if these in vitro effects were similar to those observed in the intact skeletal muscle vasculature of the dog (see Loredo et al., J. Pharmacol. Exp. Ther. 232: 301-304, 1985). The venom (0.021-4.28 microgram...

We describe a new species of carcinoecium-forming sea anemone, Stylobates birtlesisp. n., from sites 590-964 m deep in the Coral Sea, off the coast of Queensland, Australia. An anemone of this genus settles on a gastropod shell inhabited by a hermit crab, then covers and extends the shell to produce a chitinous structure termed a carcinoecium. Stylobates birtlesisp. n. is symbiotic with the her...

We performed a systematic review of the evidence supporting various treatments for envenomation by jellyfish (cnidarian) and related organisms in North America and Hawaii. Our review produced 19 pertinent primary articles. Current research demonstrates variable response to treatment, often with conflicting results according to species studied, which contributes to considerable confusion about w...

We examine the origin of harpoon-like secretory organelles (nematocysts) in dinoflagellate protists. These ballistic organelles have been hypothesized to be homologous to similarly complex structures in animals (cnidarians); but we show, using structural, functional, and phylogenomic data, that nematocysts evolved independently in both lineages. We also recorded the first high-resolution videos...

Small cytoplasmic tubules are present in the interstitial cells and cnidoblasts of hydra. They are referred to here as "microtubules." These tubular elements have an outside diameter of 180 A and an inside diameter of 80 A. By difference, the membranous wall is estimated to be 50 A thick. The maximum length of the microtubules cannot be determined from thin sections but is known to exceed 1.5 m...

The nomenclature of the purple-striped jelly® sh from southern California, currently known as Pelagia colorataRussell, 1964, is apparently in error. Our cladistic analysis of 20 characters for 15 pelagiid species indicates that P. colorata shares a common evolutionary history with members of the genus Chrysaora. There appears to be a number of characters shared among species of Chrysaora due to...

Cnidarians are characterized by the presence of stinging cells containing nematocysts, a sophisticated injection system targeted mainly at prey-capture and defense. In the anthozoan subclass Octocorallia nematocytes have been considered to exist only in low numbers, to be small, and all of the ancestral atrichous-isorhiza type. This study, in contrast, revealed numerous nematocytes in the octoc...

Hydra treated with colchicine or Colcemid become depleted of 95-99% of their interstitial cells and derivatives of this stem cell: nematoblasts, nematocytes and nerve cells. A second treatment removes most or all remaining interstitial cells. The most effective treatment is an 8-h immersion of whole Hydra attenuata in 0.04% Colcemid or 0.4% colchicine. Interstitial cells are eliminated through ...