The Production of Living Clavellina Zooids in Winter by Experiment

Abstract

IN a recent publication (“Sea-temperature, Breeding, and Distribution in Marine Animals,” Journ. Mar. Biol. Assoc., vol. xii., No. 2, p. 351) the present writer showed that there was every reason to believe that the hibernation phenomena in many marine animals are purely temperature effects. In order to test this view the positions of sixteen good colonies of the beautiful Ascidian Clavellina lepadiformis were marked on September 1, 1920, on the wooden piles of the West Wharf, Great Western Docks, Millbay, Plymouth. This Ascidian usually appears on these piles about the end of May and dies down about the end of October, and has never been recorded in winter. On September 15 and 30 the piles were again visited and a record was made of those colonies which had survived the marking. The positions of the colonies were found to be shown effectively by three long wire nails driven into the piles on the outside of the colonies at the apices of imaginary triangles. On February 23 last the laboratory collector, Mr. Wm. Searle, who assisted in the marking of the colonies, visited the piles at the West Wharf and took careful scrapings between the nails marking the positions where Clavellina colonies were seen in September, 1920.