Annual reproductive cycle of the acorn worm Ptychodera flava in Penghu, Taiwan

• Main Authors: Ching-Yi Lin, 林靖益
• Other Authors: Jr-Kai Yu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/85567864368853821114

碩士 === 國立臺灣大學 === 海洋研究所 === 99 === Acorn worm are worm-like benthic marine invertebrate which belong to phylum Hemichordata and Subclass Enteropneusta. This research focused on the population feature and the reproduction biology of the acorn worm Ptychodera flava at Chito, Penghu, Taiwan. I have studied the population densities on July 2009, November 2009, April 2010 and October 2010. I also examined monthly gonad developments by histological section and measured the body size of this species from July 2009 to December 2010. The localization of carbohydrate and lipid in gonad was studied by various histochemical staining methods. My results indicated that the density of population and average gill length changed with time. The total number of specimen collected in entire research period was 1005, include 140 females, 207 males and 658 sex unknown individuals. The total sex ratio of those specimens was different from 1:1, and the number of males specimens were more than females. Furthermore, male was dominant in the group of gill length in 0~10 mm, and female was dominant when gill length is in 20~25 mm, indicate sexual dimorphism in body size. In addition, the minimum gill length of mature male was 2.25 mm, and mature female was 5.19 mm, suggesting the minimum maturation body size was also different between sexes. The results of histochemical staining showed that carbohydrate and lipid may accumulate in the yolk cells in the gonads. I also found that carbohydrate may also accumulate in the structures in the genital wings in both sexes. These structures existed in the periphery of the gonads and attached to the gonads. Because this structures had not been described before, I named it carbohydrate body in this study. In sum, my data of the gonad development stages suggest that there is one annul reproductive period of the acorn worm P. flava at Chito. and the period was around September to December in both two years.