. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 1. Lateral view (from video) of a hovering. 4-day-old lancelel larva, illuminated by white light. The body axis is oriented 60° from the horizontal and the anterior end and ventral surface is uppermost, directed towards the surface. The long axis of the body is at an angle (a) of about 60° from horizontal; for a random sample of 4-day-old larvae (n = 115) the mean angle was 61° (±1 SD = ). Scale bar, mm. ft it :*( ii f \", I fi! ?' I l r r \ r- V I ? fl ft 3 r • if K1*1 4 i?i*. •! ( • f f j ' 1 {] i •1 Vi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 1. Lateral view (from video) of a hovering. 4-day-old lancelel larva, illuminated by white light. The body axis is oriented 60° from the horizontal and the anterior end and ventral surface is uppermost, directed towards the surface. The long axis of the body is at an angle (a) of about 60° from horizontal; for a random sample of 4-day-old larvae (n = 115) the mean angle was 61° (±1 SD = ). Scale bar, mm. ft it :*( ii f \", I fi! ?' I l r r \ r- V I ? fl ft 3 r • if K1*1 4 i?i*. •! ( • f f j ' 1 {] i •1 Vi cj p * M • » I u !/ i/ i .17 .33 .49 Seconds 0 Figure 2. Lateral views of a hovering 4-day-old larva from video (30 frames/s) taken at 5-frame intervals. Animals were observed under darkfield laser Schlieren illumination (25) to visualize the beating of the epidermal cilia. The arrowheads follow the movement of one of a series of metachronal waves moving down the body from the anterior (top) to the posterior (bottom) at approximately mm/s. Scale bar, mm. 270°. 180° Figure 3. Orientation of 4-day-old hovering larvae, as viewed from above, in the presence and absence of an incandescent light source (in- tensity approximately log Lum/m2, positioned 50cm from the ob- servation vessel). The anterior ends of the larvae point in the direction of the arrowheads, while the length of the arrow shaft shows the number of larvae in each 10° sector. The number of larvae in some sectors is indicated. Orientations of a group of larvae (n - 125): (a) after 3 h of darkness; (b) after 20-min exposure to a light source originating from one side; (c) 20 min after moving the light to the opposite side of the observation vessel. epidermal cilia. Most previous studies of larval lancelets were under conditions (very shallow culture containers and insufficient food) that did not permit hovering, but mainly favored ciliary crawling interspersed with brief ep- isodes of undu
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
