Embryonic and Larval Development in Sea Anemones (Anthozoa: Actiniaria)

Spaulding, James

Research on anemone development has been largely descriptive. In this paper I review the work on anemone development and in doing so, attempt to point to areas where additional investigation may prove fruitful. There is only a little information available on gametogenesis and fertilization. Eggs and sperm may he released by the adults with fertilization occurring in the external environment. In other cases females retain the eggs within the gastrovascular cavity or septa until after fertilization. There is some behavior reported to be associated with spawning. Anemone eggs range from 80 to 1,100 p. in diameter. They may have a smooth or a spiny oolemma. The smaller eggs undergo holoblastic cleavage, form a hollow blastula, and gastrulate by invagination. Larger eggs show delayed cytokinesis, superficial cleavage, form a solid blastula, and undergo gastrulation by a confusing variety of methods. Most gastrulae are ciliated and able to swim. Smaller zygotes become hollow planulae which may be planktotrophic or parasitic. Larger zygotes become lecithotrophic larvae which may he free living or brooded in a variety of ways. A general lack of information exists for many families and some conflicting descriptions await further investigation.

Embryonic and Larval Development in Sea Anemones (Anthozoa: Actiniaria)

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