The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR) from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four spec...

The ctenophore swimming-plate has been examined with the electron microscope. It has been recognized as an association of long cilia in tight hexagonal packing. One of the directions of the hexagonal packing is parallel to the long edge of the swimming-plate and is perpendicular to the direction of the ciliary beat. All the cilia in the swimming-plate are identically oriented. The effective bea...

Invasions of ecosystems by exotic species have been the focus of a growing body of research in applied biology and ecology, but relatively little attention has been paid to their economic consequences. Even where economic estimates have been made these often make ad hoc assumptions about the biological relationships of interest and lack grounding in economic theory. This paper develops an integ...

The lined sea anemone Edwardsiella lineata has evolved a derived parasitic life history that includes a novel body plan adapted for life inside its ctenophore hosts. Reputedly its sole host is the sea walnut, Mnemiopsis leidyi, a voracious planktivore and a seasonally abundant member of many pelagic ecosystems. However, we have observed substantially higher E. lineata prevalence in a second cte...

A new species of Glossocephalus, G. rebecae sp. nov., is described from deep-water in the Monterey Bay region of California, Eastern Pacific Ocean. It seems to be associated exclusively with the mesopelagic ctenophore Bathocyroe fosteri. This association has been observed from 541-830 m depth. It is readily distinguished from G. milneedwardsi Bovallius, 1887 by the shape of the eye fields. The ...

The lobate ctenophore Mnemiopsis leidyi and the scyphomedusan jellyfish Chrysaora quinquecirrha are seasonally important consumers in the food web of Western Atlantic and Gulf of Mexico estuaries, including Chesapeake Bay. The abundance and importance of these gelatinous species may be increasing as a result of anthropogenic alteration of these systems, particularly the increasing severity and ...

The rare ctenophore Haeckelia rubra (formerly Euchlora rubra) has long been known to have nematocysts rather than colloblasts in its tentacles. Five specimens were collected in the San Juan Archipelago, Washington State, USA in 1980 and 1981, and their feeding behavior was observed in the laboratory. We found that H. rubra readily eats the tentacles of a medusa, Aegina citrea, whose nematocysts...

Metazoa are one of the great monophyletic groups of organisms. They comprise several major groups of organisms readily recognizable based on their anatomy. These major groups include the Bilateria (animals with bilateral symmetry), Cnidaria (jellyfish, corals and other closely related animals), Porifera (sponges), Ctenophores (comb jellies) and a phylum currently made up of a single species, th...

Communication among cells was paramount to the evolutionary increase in cell type diversity and, ultimately, the origin of large body size. Across the diversity of Metazoa, there are only few conserved cell signalling pathways known to orchestrate the complex cell and tissue interactions regulating development; thus, modification to these few pathways has been responsible for generating diversi...

Transcriptome-enabled phylogenetic analyses have dramatically improved our understanding of metazoan phylogeny in recent years, although several important questions remain. The branching order near the base of the tree is one such outstanding issue. To address this question we assemble a novel data set comprised of 1,080 orthologous loci derived from 36 publicly available genomes and dissect th...