二胚中生蟲( Dicyemid mesozoan )為底棲頭足類之內寄生生物，其過去之研究多著重在分類學領域，且多在溫帶及亞熱帶水域，而自Cavolini於1787年發現這種動物以來，其生活史仍然是個謎！故此研究之目的即以台灣西南海域為模式地，於2001至2002年間調查熱帶水域之中生蟲物種及其專一性，並對中生蟲感染章魚及生活史發展時期之影響因子作分析，以期進一步了解中生蟲之生活史。研究結果顯示，自東港漁市共採集324隻章魚，包含13個種，3個屬，且感染中生蟲之章魚為9種，其中感染14種中生蟲，包含2個屬。中生蟲種類於寄主章魚種類間，並無重疊，顯示中生蟲之感染具有高度專一性。而在調查區域內之寄主章魚，具有各種不同中生蟲感染率，Cistopus indicus之91%為最高，而Octopus luteus之20%為最低。在C. indicus之分析中可發現，中生蟲之感染與季節有關，有性幼體於秋、冬季自寄主章魚體內擴散至外界，並於春、夏季大量進入寄主，接著在寄主體內發展，每一次生活史之時期轉變，伴隨著感染強度之驟降，直至成熟之菱形體時期，大量有性幼體出現腎腔中，至秋季有性幼體隨寄主尿液排至外界，下一個生活史之循環接著開始。然而Octopus marginatus的中生蟲感染則與寄主體型相關。無論於C. indicus或是O. marginatus之分析中可發現，中生蟲於同一隻寄主章魚個體內之左右腎發展程度顯著不同，故其由分開之路徑進入寄主之左右腎，而進入之先後次序則隨機而定。

Dicyemid mesozoans are endoparasites inhabited in benthic cephalopod molluscs. Previous studies of dicyemids were mostly concentrated on their taxonomy. The life cycle remains a mystery since Cavolini observed this animal in 1787. The purpose of this study is to investigate further on the dicyemid life cycle building on the limited knowledge from previous studies, and investigate the infection of dicyemid in octopuses in tropical waters, using the area in the southwestern Taiwan as a model. A total of 324 octopus hosts was collected，including 3 genera and 13 species from DungGang Fish Market from 2001 to 2002. There were 9 host species detected with dicyemid mesozoans including 14 species within 2 genera. Moreover, there is no dicyemid species overlap among the octopus species indicating high host-specificity. There is large range of the dicyemid infection prevalence among octopod hosts. Cistopis indicus has the highest prevalence (91%) and Octopus luteus the lowest (20%) in this study. In C. indicus, the infected mechanism correlated with season. The infusoriform larvae of dicyemid mesozoan dispersal from the host to sea water in the autumn and winter, then entering host in the spring and summer. The change of dicyemid life cycle stage in the C. indicus kidney correlates with the sharp decrease of infection intensity. However, the dicyemid infection in Octopus marginatus correlates with body size, not with season. Besides, there is significant difference of dicyemid development between two kidneys of the same individual, both in the analysis of C. indicus and O. marginatus. It indicates the separated way of dicyemid infection into two sides of kidneys.

謝辭 Ⅰ
中文摘要Ⅱ
英文摘要 Ⅲ
目錄 Ⅳ
圖目錄 Ⅵ
表目錄 Ⅷ
附錄目錄 Ⅸ

壹. 前言 頁次
1.1 二胚中生蟲與頭足類寄主……………………………………………………..1
1.2 中生蟲在台灣的研究現況…………………………………………………….6
1.3 實驗目的……………………………………………………………………….6

貳. 材料與方法
2.1 採集頭足類寄主……………………………………………………………….8
2.2 檢查二胚中生蟲……………………………………………………………..11
2.3 抹片的製作…………………………………………………………………..11
2.4 二胚中生蟲的分類…………………………………………………………..13
2.5 二胚中生蟲與寄主章魚、季節關係之研究
2.5.1 測量之生態因子項目…………………………………………………..13
2.5.2 測試方法………………………………………………………………..15

參. 結果 頁次
3.1 二胚中生蟲物種調查與寄主專一性………………………………………..16
3.2 章魚寄主採集族群之變因及季節，與其內相互關係之分析……………..17
3.3 中生蟲於季主章魚之感染率與感染因子之分析…………………………..18
3.4 中生蟲於寄主章魚左右腎發展程度之顯著性測驗………………………..19
3.5 中生蟲於寄主章魚之生活史發展時期及感染強度之關係………………..20
3.6 中生蟲於寄主章魚之發展成熟度，及其與寄主變因及季節之分析……..21

肆. 討論
4.1 二胚中生蟲物種調查與寄主專一性………………………………………..22
4.2 中生蟲於寄主章魚之感染率與緯度趨勢…………………………………..24
4.3 中生蟲之感染機制…………………………………………………………..25
4.4 中生蟲於寄主章魚左右腎之發展程度不同………………………………..27
4.5 中生蟲於寄主章魚腎腔內生活史之變態…………………………………..28
4.6 中生蟲之腐解………………………………………………………………..29
4.7 滴蟲型幼體由菱形體個體產出之觀察………………………..…………. 30

伍. 結論……………………………………………………………………………31

陸. 參考文獻……………………………………………………………………..32

圖………………………………………………………………………………….41
表………………………………………………………………………………….61
附錄……………………………………………………………………………….67
個人履歷………………………………………………………………………….68

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