Spawning and Dispersal in Ciona intestinalis (L.)
Spawning and Dispersal in Ciona intestinalis (L.)
复制标题
海鞘 (L.) 的产卵和传播
DOI：
10.1111/j.1439-0485.1993.tb00364.x
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
J. Havenhand
中科院分区：
文献类型：
--
作者：
I. Svane;J. Havenhand
.卵生的单生海鞘，如玻璃海鞘（L.），通常在水柱中自由产卵，卵在那里受精并发育成自由游动的非摄食幼虫。在实验室中，产卵和定居都是由光线控制的。有人建议，产卵和发育时间同步，使幼虫定居发生在最佳的光照条件下，在中午的时候，幼虫最能找到阴影栖息地。然而，我们对田间种群的观察表明，玻璃海鞘可能在一天中的任何时间产卵和定居。自由产卵的卵具有负浮力和轻微的粘性，可以附着在任何可用的基质上。卵也可以以粘液丝的形式释放出来，粘液丝特别具有粘性，很容易粘附在成年玻璃海鞘和其他表面上。在所有情况下，受精和发育都正常进行。实验室研究表明，刚孵化的幼虫可能会逃到浮游生物中，也可能会被留在粘液串中直到定居。因此，密集聚集的成年人和新定居的玻璃海鞘，这是常见的领域可以解释为简短的分散由于粘液串产卵和底栖保留的鸡蛋。
总结
在野外，同时发现了处于不同发育阶段的玻璃海鞘胚胎，表明产卵并不局限于一天中的特定时间。游离卵具有负浮力，并具有轻微的粘性。卵在粘液带中产卵，在那里受精和发育。这些字符串被保留在底栖生物。附着和随后的变态发生在粘液串中，但在实验室中，40%至60%的幼虫逃到浮游生物中。在现场观察到的成年和少年的玻璃海鞘聚集可以解释粘液串产卵和底栖保留的鸡蛋。
. Oviparous solitary ascidians, such as Ciona intestinalis (L.), generally spawn freely into the water-column where the eggs are fertilized and develop into free-swimming non-feeding larvae. In the laboratory, both spawning and settlement are controlled by light. It has been suggested that both spawning and development time are synchronized so that larval settlement takes place under optimal light conditions in the middle of the day when larvae are best able to locate shaded habitats. Our observations of field populations, however, have shown that Ciona may spawn and settle at any time of the day. Freely spawned eggs, which are negatively buoyant and slightly adhesive, may become attached to any available substratum. Ova can also be released in mucus strings which are particularly adhesive and will readily adhere to adult Ciona and other surfaces. In all cases, fertilization and development proceed normally. Laboratory investigations have shown that newly hatched larvae may either escape to the plankton or be retained in the mucus string until settlement. Thus, the dense aggregations of both adults and newly settled Ciona which are commonly observed in the field could be explained by abbreviated dispersal due to mucus string spawning and epibenthic retention of eggs.
Summary
In the field, Ciona intestinalis embryos at different developmental stages are found simultaneously, indicating that spawning is not confined to a specific time of day. Free eggs are negatively buoyant and slightly adhesive. Eggs are spawned in mucus strings, where fertilization and development takes place. Such strings are retained epibenthically. Settlement and subsequent metamorphosis takes place in the mucus strings, but in the laboratory 40 to 60 % of the larvae escape to the plankton. The aggregation of both adult and juvenile Ciona observed in the field can be explained by mucus string spawning and epibenthic retention of eggs.