. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FEEDING BIOLOGY OF D1SCOSOMA 223. DAY NIGHT DAY NIGHT DAY NIGHT Total oral disc discal tentacles Oral disc margin Figure 9. Boxplots for the surface areas of different portions of the oral disc during the day and night. There are significant differences in surface area between day and night for the total oral disc (P < ) and the oral disc margin (P : Paired /-tests for each comparison). The central box part of the display (the hinges) indicates the interquartile range, the absolute difference between the 25th and
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FEEDING BIOLOGY OF D1SCOSOMA 223. DAY NIGHT DAY NIGHT DAY NIGHT Total oral disc discal tentacles Oral disc margin Figure 9. Boxplots for the surface areas of different portions of the oral disc during the day and night. There are significant differences in surface area between day and night for the total oral disc (P < ) and the oral disc margin (P : Paired /-tests for each comparison). The central box part of the display (the hinges) indicates the interquartile range, the absolute difference between the 25th and 75th percentiles. The central horizontal line is the median, and the "whiskers" that extend out from the central box indicate the main body of the data and are calculated using the formula: hinge ± (interquartile range). Any data values that extend out beyond these limits are plotted with a circle (n = 61). the day, more than two contacts to the discal tentacles with a pasteur pipette were usually required to elicit the response, but some individuals did not close after even 20 contacts or forceful blows. At night most individuals closed after the first few contacts and exhibited a typical envelopment response. The sensitivity of the animals ap- peared to be related to their degree of expansion of the oral disc and their posture. In the laboratory, those indi- viduals displaying a typical feeding posture were most sensitive to mechanical stimuli, while animals that were in a normal daytime posture rarely responded, indepen- dent of the ambient light levels. A forceful stream of sea water (approximately 1 mi- s'1) directed at the oral disc from a pipette or syringe was also capable of eliciting the envelopment response. How- ever, gentle streams of seawater (approximately mi- s'1) that only lightly swayed the discal tentacles did not elicit envelopment. This allowed the presentation of chemicals in the stream of seawater. In field tests Artemia homogenate was
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
