Feeding behavior of dinoflagellate, Oxyphysis oxytoxoides, on ciliates
1993
Inoue, H. (Tokyo Univ. (Japan). Faculty of Agriculture) | Fukuyo, Y. | Nimura, Y.
Oxyphysis oxytoxoides (Dinophysiales) fed on both loricated and non-loricated species of ciliates by piercing the prey cell with a feeding tube. All species were collected from Tokyo Bay during March and May, 1987, and during April and June, 1988. The size of the ciliates was equal to or larger than the dinoflagellates. When feeding on loricated ciliates, O. oxytoxoides swam around the prey and touched the lorica by its apex several times, before attacking the prey. The predator intruded its epitheca into the lorica and pierced the cytoplasm of the prey with the feeding tube. Within seconds after injecting a small amount of fluid through the tube into the prey cell, the dinoflagllate began to such up the cytoplasm. As sucking proceeded, a number of food vacuoles appeared and the breadth of the dinoflagellates expanded gradually. Usually the predator began to swin before the completion of feeding, dragging the schrinking prey by the feeding tube. The lorica of the prey was often discarded and only the round cell body remained. When feeding on non-loricated ciliates, such as Strombidium sp., O. oxytoxoides seems to be able to pierce any part of the prey with the feeding tube. Several predators may feed on the same ciliate cell,and up to ten dinoflagellates have been observed to feed at the same time. Well-fed O. oxytoxoides had a widely expanded hypotheca and many vacuoles. It showed longitudinal binary fission once or twice during the following dark period. Dinophysis rotundata was observed to feed only on loricated ciliates in similar way as O. oxytoxoides did. From the present observation O. oxytoxoides can be recognized as a secondary consumer. This is different niche from either primary producer or primary consumer, which are commonly thought to be possessed by dinoflagellates
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