SHERRARD, K.M.: Limits to early juvenile suspension feeding performance in sea squirts
Post-metamorphic marine invertebrates are maximally different from adults in size, though often similar to them in morphology and behavior. How does small size affect early juvenile performance? Ascidians, as sessile suspension feeders, provide a convenient system in which to investigate this question. In the first weeks of juvenile existence there are a number of morphological changes which potentially influence suspension feeding performance: the siphons expand and rotate to an upright position, the ciliated stigmata lenghten and multiply, and the animal grows away from boundary layers near the substrate. In the solitary species Corella inflata, individuals increase greatly in size, from a siphonal Reynolds number of 10-2 to 102. In the colonial species Distaplia occidentalis, the first zooid doubles in length during the first two weeks, after which additional zooids begin to appear. High resolution, in vivo particle tracking experiments using early juvniles of these two species suggest that the high cost of resistance to flow in a small siphon is balanced by its greater ability to draw in particles.
