Re: Egg masses; the direction they spiral

March 12, 1998
From: Irina S.Roginskaya

Dear Bill!
Many thanks for your prompt answer. The direction of spiral spawns in southern hemisphere disturbs me for years (Roginskaya, 1987, 1991). This interest arose after discovering of the works of Risbec, 1928., Kenny, 1970., Bandel, 1976 and the photograph of eight clockwise directed spawn presented by Mr.T.E.Pitman of Rangiora in New Zealand Camera, (Oct.1972). Are you quite sure that your nudibranchs begin their Archimedean spiral formation from the centre and not from the largest whorl? Bandel, 1976, near equator, found both left- and right-coiled spawns. And his Favorinus branchialis could start both from the centre and from the largest whorl, sometimes even during the same egg-laying. Costello, 1938 observed the same reverse mode in Hopkinsia rosacea from Monterey Bay. Of course you can guess that I suspect Coriolis acceleration. My time is over.
Best wishes.
Irina S.Roginskaya.
Moscow, Russia

Roginskaya I.S., 1998 (Mar 12) Re: Egg masses; the direction they spiral. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Anyone out there with comments or observations?... Bill Rudman

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