Vertical Migration and Feeding in Sagitta Elegans Verrill
Vertical Migration and Feeding in Sagitta Elegans Verrill
复制标题
线虫 Verrill 的垂直迁徙和进食
作者：
S. Pearre
野外研究确立了秀丽箭虫昼夜垂直迁移规律。在实验室条件下研究了该物种的光反应，发现了正趋光性和光控趋地性，并据此提出了昼夜迁移的深度控制模型。野外研究表明，光抑制摄食，并表明动物的饱足状态影响其深度控制机制。通常的方法来评估垂直迁移分层样本的批评，并解释“午夜下沉”，涉及快速周转的喂养动物在表面沃茨，提供。在夏季和冬季的饮食箭虫进行了检查，并与不同的桡足类的可用性。昼夜迁移的关系，摄食活动导致了优势的表面生活桡足类在箭虫的饮食。这种影响会扭曲食物选择的计算。适应值的理论进行了简要的讨论，得出的结论是箭虫离开表面沃茨在白天主要是为了避免视觉直接捕食。
Field studies established diel vertical migration of Sagitta elegans Verrill. Light reactions of this species were investigated in the laboratory, where positive phototaxis and light—controlled geotaxis were found. Based on these, a model for depth control in diel migration is proposed. The field studies disclosed that light inhibits feeding and suggested that the state of satiation of the animal influences its depth control mechanism. The usual method of assessing vertical migration from stratified samples is criticized, and an explanation of “midnight sinking,” involving rapid turnover of feeding animals in surface waters, is offered. The diet of Sagitta was examined in summer and winter and related to the availability of different copepods. The relationship of diel migration to feeding activity led to a preponderance of surface—living copepods in Sagitta's diet. This effect can distort calculations of food selection. Theories of adaptive value are briefly discussed and it is concluded that Sagitta left the surface waters during the day primarily in order to avoid visually directed predation.