. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 3. Capture of a plastic sphere by an actinotrocha (Phunmopsis virijis) in ventral-anterior view. The black bar is to one side of the plastic sphere. Numbers at the upper right of each frame are time in seconds from the first frame in the sequence. The sphere contacted the tentacle near the tip and moved most of the length of the tentacle during the hood lift between and s. The width of the oral hood in the first frame is 460 fjm. lifting and lowering of the hood. When an actinotrocha lifted and lowered its o
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 3. Capture of a plastic sphere by an actinotrocha (Phunmopsis virijis) in ventral-anterior view. The black bar is to one side of the plastic sphere. Numbers at the upper right of each frame are time in seconds from the first frame in the sequence. The sphere contacted the tentacle near the tip and moved most of the length of the tentacle during the hood lift between and s. The width of the oral hood in the first frame is 460 fjm. lifting and lowering of the hood. When an actinotrocha lifted and lowered its oral hood in rapid succession, a particle moved proximally with each lift and distally with each lowering (Fig. 5). The motion of the particle in this and other examples exactly followed the motion of the hood. The oral hood sometimes lifted when no particle was captured. When larvae were disturbed, they often raised the hood far beyond the elevation that accompanied parti- cle captures. Lifting the oral hood may serve other func- tions, such as rejection of particles, escape, or defense, but our observations of the close correspondence between encounters with particles and elevation of the oral hood indicated a response to individual particles and a role in captures. The improbability of hood lifts and captures coinciding by chance alone was demonstrated by analysis of videorecorded sequences of 10-s duration with an acti- notroch of P. viridis capturing plastic spheres 20 /Jin in diameter. In the first of these sequences, four plastic- spheres passed close to the tentacles. Two passed with a hood lift and were captured. One passed with a hood lift but no capture. One passed without a hood lift. The ob- served proportion of particles passing that coincided with a hood lift was , and the proportion of particles cap- tured was The proportion of particles passing that would coincide with hood lifts by chance alone can be estimated by assuming that a capture or a hood lift
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
