Annual reproductive cycle of peanut worm, Sipunculus nudus from Thailand
Peanut worms have long been globally utilized as human food and fishing bait but their importance as a research animal to monitor marine environmental quality has only recently been exploited. There must be adequate knowledge of the breeding and culturing practices of a research species to provide reliable scientific data. At least 100 specimens of Sipunculus nudus Linnaeus, 1766 were collected from Mod Tanoy Beach, Kantang district, Trang province, Thailand each month from September 2012 to August 2013. The annual reproductive cycle was monitored of 60 specimens randomly selected and dissected for sex determination and inspection of male and female gamete stages. Data for 720 worms were collected and revealed a sex ratio of 1:1. Mature eggs and sperm plates were observed every month and the results indicated that spawning occurred throughout the year. S. nudus specimens from Mod Tanoy Beach, Thailand did not show a pattern of an annual reproductive cycle unlike S. nudus in China and other species of peanut worm which exhibited strong spawning patterns during the spring and summer months.