Читать книгу Life in the Open Ocean - Joseph J. Torres - Страница 103

Development proceeds from a planula larva and differs between groups. In the physonects, the planula becomes a siphonula larva as summarized in Figure 3.32 from Mackie (1986). The two budding zones produce the nectophores and the gastrozooids, gonophores, and bracts as the stem elongates during development. Development in the Calycophorae is somewhat different, with the initial production of a larval nectophore followed by development of the stem and gastrozooid. The larval nectophore is retained in some taxa (e.g. Sphaeronectes) and lost in others (e.g. Hippopodius). Early development in the cystonects is currently undescribed but defined budding zones beneath the float have been identified in both Physalia and Rhyzophysa.