Average swimming velocities were 1.25 mm/s for larvae in FSW and 3.92 mm/s for larvae in UCSW. The maximum speed for most larvae exposed to UCSW was about 5.5 mm/s, but a few larvae reached speeds of 7 mm/s.
Molecular weight separation and enzymatic treatments of UCSW
The activity of UCSW fractions above 10 kDa (F-ratio = 1.1, P > 0.34) and below 50 kDa (F = 0.73, P > 0.44) was equal to that of untreated UCSW.
The most extreme enzymatic incubation conditions (5.0 and 9.5 at 37 [degrees]C for 30 m) had no effect on the activity of UCSW (7 of 10 and 8 of 10 larvae were induced, respectively).
In response to UCSW (seawater conditioned with the thalassinid shrimp Upogebia pugettensis), competent larvae of Phoronis pallida exhibited an exploratory behavior in a dosage-dependent manner.
Resolving the lipid-like properties of the behavioral cue in UCSW will require finer chemical analyses.
The complete degradation of the activity of UCSW by arginase points to an important peptide component.
Table 1 Effect of different possible cue sources for behavioral and metamorphic activity of competent larvae of Phoronis pallida Cue source* S/n UCSW 5/5 Burrow walls 5/5 Upogebia gut tissue 5/5 Upogebia carapace 0/5 Upogebia gut bacteria Yellow bacteria 0/10 Orange bacteria 0/10 White bacteria 0/10 Bacterial mixture 0/10 Upogebia hindgut gland extract 0/30 NCSW 1:10[dagger] 0/60 None of these cue sources induced metamorphosis.