Biological study of the Acrossocheilus paradoxus(Gunther)

• Main Authors: Chiou, Tsyr-Huei, 邱慈暉
• Other Authors: Wang Jing-Ping
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/84716977129196776906

碩士 === 國立成功大學 === 生物學系 === 84 === The sexual dimorphism, osteology, histology, feeding behavior and morphometric study of the Acrossocheilus paradoxus are described. The existance of protuberances on the anal fin and the epidermis around the anal fin can be used as a character to distinguish between the male and the female Acrossocheilus paradoxus. The branchial arches of Acrossocheilus paradoxus contain basibranchials, hypobranchials, ceratobranchials, epibranchials, and pharyngeobranchial, which are lacking in the common carp, Cyprinus carpio, but are present in most of the other cyprinid fishes. The presence of metazygapophysis between body vertebrae can protect the spinal cord of Acrossocheilus paradoxus from injury when the fish is swimming in fast water. Besides, there are ligments connecting the end of the 12th ribs and the bases of the outer most ventral fin rays in Acrossocheilus paradoxus. This connection can increase the maneuverability of the pelvic fins, hence, increase its moving ability. Acrossocheilus paradoxus has three rows of canine pharyngeal teeth on the fifth brachial arches. The external muscle layer of the digestive tract is not well developed, however, the mucosal layer are well developed and heavily folded in Acrossocheilus paradoxus. The histology of digestive system in the Acrossocheilus paradoxus is similar to that of the other carnivorus fishes. The spermatogonia in Acrossocheilus paradoxus distributed along the entire length of the testicular tubules, indicating the fish can breed repetitively within one breeding season. The number of the photoreceptors are greater than the olfactory receptors, suggesting the optic system of the Acrossocheilus paradoxus are better developed than the olfactory system. This may have great help in catching prey in clear water. There are three types of tail development, including upward growing, symmetric growing and downward growing. These three kinds of growing patterns are related to neither collection sites nor sex. The causes of different growth of the tail remain to be studied. The intestinal contents include many chitinous exoskeleton of water insects, fiberous algae, and diatoms, excluding snails, mussels, and other fishes. The digestive contents and the digestive histology suggest that Acrossocheilus paradoxus is carnivorous.