. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 568 S. KAJIWARA AND M. YOSHIDA like a swarm of mosquitoes. This type of behavior starts 30 min after hatching in C. savignyi and 1 h in A. sydneiensis samea. The sequence of swarm formation is shown in Figure 2. Close observation of individual larvae revealed that while swimming beneath the water surface, they often stopped swimming and sank passively. The frequency of larval stopping was increased when two larvae collided with each other. After sinking to an indeterminate depth, larvae resumed upward swimming slightly outsi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 568 S. KAJIWARA AND M. YOSHIDA like a swarm of mosquitoes. This type of behavior starts 30 min after hatching in C. savignyi and 1 h in A. sydneiensis samea. The sequence of swarm formation is shown in Figure 2. Close observation of individual larvae revealed that while swimming beneath the water surface, they often stopped swimming and sank passively. The frequency of larval stopping was increased when two larvae collided with each other. After sinking to an indeterminate depth, larvae resumed upward swimming slightly outside the original sinking line. In this way, the larvae form first a ring pattern when viewed from above ( min in Fig. 2) which becomes smaller and smaller until a single column is formed at the end ( min in Fig. 2). Stage III: h after hatching Larvae begin to show a shadow reflex, swimming upward within 2 s after shading. Note that in the side view of the 10 s recording in Figure 3, the number of larvae on the bottom is much reduced. Negative phototaxis is not apparent as yet, so that the distribution pattern in the trough remains the same as Stage II to the end of the recording period (30 s in Fig. 3). Stage IV: h after hatching Larvae still form the swarm as before but now the size increases because the degree of aggregation has decreased (Initial in Fig. 4). A notable difference from the preceding stage is that the swarm disperses in about 10 s after shading. The massive shift towards the darker side (rightside in 10 s in Fig. 4) during shading indicates the onset of photonegativity. 30 s after shading, a few larvae begin to sink slowly. They form a swarm again after about 10 min when left undisturbed. Larvae of A. sydneiensis samea also become negatively phototactic about 3 h after 30sec mi n FIGURE 2. The sequence of swarm formation which occurs between Stage II and IV. This experiment was done with Stage III larvae. The time after stirri
Size: 4195px × 596px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
