Meeting Abstract
P1.48 Saturday, Jan. 4 15:30 Can the feeding larvae of marine invertebrates capture bacteria-sized particles by drinking? JAECKLE, W.*; PERNET, B.; Illinois Wesleyan Univ., Bloomington; California State Univ., Long Beach wjaeckle@iwu.edu
The feeding larvae of some marine invertebrates ingest bacteria-sized (‹1 µm) particles, but little is known of the physical mechanism(s) of particle capture. To examine the possibility that larvae collect these particles by ingesting seawater, we compared drinking and particle clearance rates of veligers of Crepidula onyx and bipinnariae of Patiria miniata. Drinking was measured as the fluorescence of individuals or pairs of larvae after ≤20 min exposure to FITC-labelled dextran, and clearance rates were estimated from the number of 0.45 µm polystyrene beads ingested after 10 min incubation in a bead suspension. Fluorescence of larvae generally reached stasis within the first 10 min of exposure; epifluorescence microscopy confirmed the label was localized to the digestive system. Veligers ingested seawater at an average maximal rate of ≈24 nL/h, and cleared 0.45 µm beads at a mean rate of 231 nL/h; bipinnariae swallowed seawater at an average maximal rate of ≈26 nL/h, and cleared 0.45 µm beads at a mean rate of 35 nL/h. These data suggest that bipinnariae might capture bacteria-sized particles simply by drinking seawater and retaining ingested particles in their guts, but veligers must also concentrate these particles by some other mechanism (presumably using velar cilia). Gut volumes averaged ≈1 nL (C. onyx) and 10 nL (P. miniata), suggesting that if drinking is continuous, the gut of C. onyx would be flushed ≈24 times/h, and that of P. miniata ≈3 times/h. This has important implications for our understanding of how particulate foods are digested and assimilated by larvae. A rapid flow of seawater through the digestive system may also provide opportunities for larvae to assimilate dissolved organic materials present in this flow across the gastric epithelium.
