The evolutionary relationships between the earliest branches of the animal kingdom - bilaterians, cnidarians, ctenophores, sponges and placozoans - are contentious. A new phylogenomic analysis suggests a return to old ideas.

Animal evolution is often presented as a march toward complexity, with different living animal groups each representing grades of organization that arose through the progressive acquisition of complex traits. There are now many reasons to reject this classical hypothesis. Not only is it incompatible with recent phylogenetic analyses, but it is also an artifact of 'hidden biology', that is, blin...

A major problem in understanding animal evolution is where early branching phyla, especially sponges and comb jellies (sea gooseberries), sit in the tree of life. A new study seeks to overcome this problem by sampling more species and data cleansing.

Marine zooplankton research in Brazil has been primarily descriptive, with most studies focusing on community structure analysis and related issues. The composition and spatial distribution of several taxonomic groups are currently well known, although less-abundant and small-sized taxa as well as initial stages of almost all species have received little attention. Some numerically important ta...

Transparency measurements (at 400 to 700 nm) were made on living specimens of 29 common species of gelatinous zooplankton from the Northwestern Atlantic Ocean and Gulf of Mexico. Percent transparency ranged from 91% for the hydromedusa Sibogota typa to 0.51% for the pteropod Clione limacina. Percent transparency was linearly and positively correlated with wavelength, with slopes of the regressi...

Weightand carbon-specific rates of respiration for 4 mesopelagic gelatinous zooplankton (2 ctenophores, 1 trachymedusa and 1 pelagic holothurian) measured in situ were 2 to 5 times higher than those from shipboard incubations. These results support the theory that removal of deep-living gelatinous species from natural environments can adversely affect their metabolism. The disparity between in ...