Fertile blades of Ulvu pertusa appeared during a neap tide series at Tsuyazaki, as was reported previously. In 1974, however, fertile sporophytes were observed through the series even after they were outnumbered by fertile gametophytes. Each blade liberated swarmers not fortnightly, but several times during a neap tide series, Fruiting on 2 or more successive days was quite common, and 2 blades out of 31 were observed to fruit 5 successive days. Tagging blades with vinyl spaghetti was effective

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... to follow each one at habitat. Fruiting interval changed easily when a blade was put in an aquarium with no emersion. Fruiting on successive days is common and a 3-6-day interval was also dominant, Growth rate was high enough to cover the loss in length due to fruiting on the preceding day. One blade was found to be sterile and to have a very high growth rate reaching 12.5 times lengthwise in 20 days. Distal area had a higher rate, while basal area did not elongate.