Figure 1

UV Light Greatly Facilitates Visually Guided Prey Capture in Larval Zebrafish

(A) Schematic representation of visual prey capture by larval zebrafish.

(B) Setup for filming paramecia. A filter wheel equipped with UV and yellow bandpass filters was positioned in front of the charge-coupled device (CCD) camera to image paramecia in a naturalistic tank in the sun.

(C) Peak-normalized spectra for the UV and yellow channels (thick lines; STAR Methods) superimposed on the zebrafish’s four opsin absorption spectra (shadings). The spectral overlap between the UV and yellow channels with each opsin is indicated (thin lines). Abs., absorption; Tr., transmittance.

(D) Example frames from the yellow and UV channels taken consecutively from the same position.

(E) Zoom in from (D), with line profiles extracted as indicated. Arrowheads highlight paramecia visible in the UV channel. See also Video S1.

(F) Schematic of behavioral setup. Individual larval zebrafish (7–8 dpf) in the presence of free-swimming paramecia were head-mounted and filmed from above, with infrared illumination from below.

(G) Top illumination was provided by intensity-matched UV (374 ± 15 nm) or yellow (507 ± 10 nm) LEDs, which mainly activated UV/blue and red/green opsins, respectively, as indicated.

(H) Top: zebrafish consistently responded more readily to passing paramecia with full prey-capture bouts (eye convergence + tail flicks, each event indicated with a marker) during UV-illumination periods. See also Video S2. Individual trials (left) and summary statistics (right). This difference was abolished when UV cones were ablated (bottom). Mann-Whitney U test, UV versus yellow light in wild-type (WT) fish: p < 0.01; WT versus UV killing under UV light: p < 0.001; UV versus yellow light in UV killing fish: p > 0.05; n = 12 each for WT and UV cone ablation.