Assessment of structural and functional similarities and differences between caeca of the bluegill

Bluegill Lepomis macrochirus possess six to eight gastrointestinal caeca, >70% having seven. The terminal caeca toward abdominal edge (C6, C7) were always larger than the terminal caeca toward the vertebral column (C1, C2) and middle caeca (C3, C4, C5). The caeca varied in relative thickness of the histological layers and lumen space. The terminal caeca (C1, C2, C6, C7) have anatomical positional advantage over, and possess more contents, than the middle ones (C3, C4, C5) in both field and laboratory conditions. Hence, all caeca in bluegill may have the same function but their functional potentials are not the same. Two factors, size of caeca and anatomical position of caeca, apparently work synergistically to cause variation in their functional efficiency.