A Description of the Sea Anemone Stomphia didemon sp. nov. and Its Development

Abstract

Stomphia didemon is described as a new species of sea anemone from
\nthe San Juan Archipelago, Washington. It possesses about 192 tentacles and 96
\npairs of mesenteries. The cnidom is spirocysts, basitrichs, microbasic b-mastigophores,
\nand microbasic p-mastigophores. S. didemon spawned in April and May.
\nThe eggs are 750 to 800 /lm in diameter, orange, and centrolecithal; cleavage is
\nsuperficial, equal, and incomplete. Endoderm formation is by unipolar ingression
\nfrom a fold in the surface of the blastula. Settlement of the planulae is favored by
\nthe presence of sand or gravel. Attempts were made to fertilize eggs of S. coccinea
\nwith sperm from S. didemon, but the cross-fertilized eggs failed to develop.