The response of the salp, <i>Pegea confoederata</i>, to high levels of particulate material: Starvation in the midst of plenty1

Abstract

When the pelagic tunicate Pegea confoederata is presented with concentrations of particulate material equivalent to levels found in neritic areas, its feeding mechanism is disrupted. A bolus is formed that blocks the esophagus, dramatically decreasing the amount of material that enters the stomach. This bolus never occurs at particle concentrations &lt;0.5 ppm, and always forms at particle concentrations &gt; 5.0 ppm. For oceanic waters, 0.5 ppm lies in the upper range of values, so that it appears that P. confoederata is adapted for feeding on average concentrations of particulate material in the open sea. These results are in contrast to those with most of the calanoid copepods that have been studied. Because P. confoederata feeds on oceanic average amounts of food, it can be more evenly distributed throughout the great oceanic central water masses, decreasing the likelihood of its discovery by predators.