Egg-case diversity among dogfish, Scyliorhinus canicula (L.): a study of egg laying rate and nidamental gland secretory activity



Egg-case size, shape and pigmentation are distinctive features of each female lesser-spotted dogfish, Scyliorhinus canicula. During 9 months captivity under constant conditions (water, temperature, photoperiod, food), a laying sequence reminiscent of an annual cycle was observed in three females. While oocyte size and (with exceptions) egg-case weight remained constant, there was a marked decrease of the‘albumen’jelly secreted by the anterior halves of nidamental glands.