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Vol. 40 No. 3, 2001
Distribution and Sexual Reproduction of a Seagrass-bed-inhabiting Actiniarian, Phymanthus strandesi (Cnidaria: Anthozoa: Actiniaria: Phymanthidae), at Hsiao-Liuchiu Island, Taiwan
Ming-Doun Lin1,2, Chaolun Allen Chen1,3,* and Lee-Sing Fang4
1Institute of Zoology, Academia Sinica, Taipei, Taiwan 115
2Institute of Marine Resources, National Sun Yat-sen University, Kaohsiung, Taiwan 804
3Institute of Oceanography, National Taiwan University, Taipei, Taiwan 106
4National Museum of Marine Biology and Aquarium, Hengchun, Taiwan 944
Ming-Doun Lin, Chaolun Allen Chen and Lee-Sing Fang (2001) Distribution and sexual reproduction of the seagrass-inhabiting actiniarian, Phymanthus strandesi, was investigated at Gerban, Hsiao-Liuchiu, Taiwan from July 1997 to June 1998. P. strandesi
was distributed in the shallow intertidal zone of the reef flats with a
mean density of 511 individuals/m2 . The distribution pattern of P. strandesi was contagious, and was significantly correlated with the presence of the seagrasses, Thalassia hemprichii and Halodule uninervis. P. strandesi is
a small dioecious actiniarian with a mean pedal disc diameter of 0.32
cm. A high proportion of the anemones were sexually indeterminate,
whose sizes were significantly smaller than those of both males and
females. The mean fecundity of females was 294 eggs/individual. The
released eggs were 500 to 560 µm in diameter. Gametogenesis examined by
paraffin section showed no distinct developmental pattern among monthly
samples, suggesting that P. strandesi might
reproduce continuously throughout the year. Although with a small body
size and low fecundity, the large eggs, continual gametogenesis, and
contagious aggregation in the seagrass bed might ensure the successful
sexual reproduction of P. strandesi.
Key words: Actiniarian, Sexual reproduction, Distribution, Gametogensis, Seagrass bed.
*Correspondence: Tel: 886-2-27899549. Fax: 886-2-27858059. E-mail: cac@sinica.edu.tw
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