. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. B. 1 mm Figure 1. Representative paths of larvae swimming off the bottom in filtered seawater. Data are computer-digitized video records of vertical paths as viewed from the side of a chamber. Each path of dots represents the position of a given larva at consecutive two-frame intervals with video collected at 10 frames per second. The same scale bar applies to all paths. (A) Representative paths of precompetent. 8-d-old planktotrophic larvae, showing the frequent turns and meandering movement typical of immature larvae. (B)
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. B. 1 mm Figure 1. Representative paths of larvae swimming off the bottom in filtered seawater. Data are computer-digitized video records of vertical paths as viewed from the side of a chamber. Each path of dots represents the position of a given larva at consecutive two-frame intervals with video collected at 10 frames per second. The same scale bar applies to all paths. (A) Representative paths of precompetent. 8-d-old planktotrophic larvae, showing the frequent turns and meandering movement typical of immature larvae. (B) Paths of competent, 32-d-old planktotrophic larvae. Larvae increasingly swam towards the bottom in straighter. faster paths as they matured to competence. (C) Swimming behavior of competent, 1-d-old lecithotrophic larvae. Paths show the rapid, vertically oriented swimming that characten/es nonfeeding larvae of Atderia modesla. throughout the water column and did not respond to chang- ing light regimes (Fig. 2A). As planktotrophic larvae neared competence, the trend was for fewer larvae to swim off of the bottom (Fig. 2B). Most competent, 32-d-old planktotro- phic larvae remained on the bottom in initial light treat- ments, as did 1-d-old lecithotrophic larvae (Fig. 2C, D). Competent larvae of both development modes displayed a striking shadow response: both 32-d-old planktotrophic lar- vae and 1-d-old lecithotrophic larvae immediately swam up into the water column following a transition to darkness (Fig. 2C, D). After I min, most larvae settled out of the water column and returned to the bottom, where they re- mained during a subsequent exposure to light. The effects of age and photostimulation on larval position in the water column were tested using a two-way ANOVA (Table 3). Light or dark treatment had a significant effect on the number of swimming larvae (P < ), and the interac- tive term for light treatment versus larval developmental class was also significant (P
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
