Post-settlement Diet Shift of Chlorurus sordidus and Scarus schlegeli (Pisces: Scaridae)

白斑鸚哥魚（Chlorurus sordidus）和史氏鸚哥魚（Scarus schlegeli）(Pisces:Scaridae鸚哥魚科）定棲後食性之轉變

陳麗淑(Li-Shu Chen)

《Zoological Studies》 41卷1期 (2002/01) Pp. 47-58

摘要

本研究探討澳洲大堡礁北部蜥蜴島（Lizard Island）體長從15-30 mm之白斑鸚哥魚（Chlorurus sordidus）和史氏鸚哥魚（Scarus schlegeli）仔魚由雜食性轉變為草食性其消化系的發育，包括牙齒以及腸子盤旋的形式的改變。這兩種魚最初有獨立的犬齒，但成長後就消失了；腸子從簡單的一個轉折，改變為複雜的兩次轉折。體長在15 mm 以下的仔魚，胃內含物主要為小型底棲甲殼類和有孔蟲；但隨著成長，藻類及沙子的比率都跟著增加。在棲所利用方面，這兩種仔魚都在死珊瑚和碎石上取食，但體長小於20 mm時，他們則以取食藻叢中的甲殼類為主。比較結果，他們食性變化的時機隨著消化器官形狀的改變決定，而非所利用棲所不同所造成。

關鍵字

消化系統 ； 鸚哥魚 ； 攝食場所 ； 功能形態學 ； 覓食

並列摘要

Ontogenetic changes in the development of feeding structures and feeding habits of juvenile parrotfishes Chlorurus sordidus and Scarus schlegeli (Family: Scaridae) were examined at Lizard Island on the northern Great Barrier Reef, Australia. A shift from omnivorous feeding to feeding on plant materials was observed, and this occurred over the size range of 15-30 mm TL. Ontogenetic changes were observed in teeth as well as in gut coiling patterns. Individual teeth were present in newly settled scarids (10 mm TL) but were totally lost when size increased to 26 mm TL. The change in gut coiling patterns occurred mainly in the mid-intestine, from being non-constricted to having a constricted ilial wall. The tracts also changed from 1 sinistral loop to 2 loops by the end of the observation period. The difference in gut length between the 2 species was caused by the different coiling patterns. Small individuals (15 mm TL) of both species were omnivorous with diets dominated by crustaceans and foraminifera. Significant increases in the amounts of algal material and sediment taken were seen as fish grew. With respect to microhabitat utilization, both species fed mainly on dead coral and rocky substratum. Algae, with their associated high density of crustaceans, were used by both species as a feeding substratum when individuals were small (TL ＜ 20 mm). Dietary changes of post-settled C. sordidus and S. schlegeli were directly related to morphological changes in the alimentary tract rather than the differences of habitat utilization.

並列關鍵字

Digestive system ； Parrotfish ； Feeding habitats ； Functional morphology ； Foraging