嘉陵江下游蛇肠道形态结构及其异速生长模式

Morphological structure and allometric growth pattern of Saurogobio dabryi intestine in the lower reaches of Jialing River

  • 摘要: 对2015—2016年间采自嘉陵江下游合川江段的233尾蛇样本进行肠道形态结构的研究,分析蛇肠道生长模式的特点,并从功能差异的角度探讨其对个体能量需求的适应。结果显示,蛇肠道为Z型盘曲模式,比肠长(RGL)为0.612 8,属肉食性鱼类肠道类型;蛇肠道可分为前肠、中肠和后肠3个分区,各分区在外部形态、内部结构以及肠道指数方面均存在较为明显的差异。Segmented结果分析表明,蛇肠道属异速生长,整体肠道于2龄时出现生长拐点(TL=145.07 mm),拐点前为快速生长,拐点后为等速生长。同时,肠道各分区的生长模式不尽相同,前肠和中肠始终保持等速生长,仅后肠从快速生长经拐点转换为等速生长。蛇肠道各分区生长模式的差异可能与其功能分化有关,在拐点前,蛇通过后肠的快速增长来提高摄食频率,从而满足其大量的能量需求。本研究不仅能为今后开展蛇的人工养殖提供重要理论依据,同时为探讨鱼类肠道异速生长与食性间关系进行了有益的尝试。

     

    Abstract: To study the intestinal structure characteristics and the relationship with its growth pattern of Saurogobio dabryi, a total of 233 individuals were collected from the lower reaches of the Jialing River (Hechuan section) from 2015 to 2016. Morphological observation results showed that the intestinal structure of S. dabryi was Z-shaped, and belonged to carnivorous fish gut according to its relative short gut length (RGL) index (0.612 8). Based on its morphological structure, the intestine could be divided into three parts, the foreintestine, the midintestine and the hindintestine, with obvious difference in external morphology, internal structure and intestinal index. The growth pattern of S. dabryi intestine was allometry, with 2-year growth inflexion age and 145.07 mm corresponding fish total length (TL). Before and after the inflection point, there was different growth pattern of intestine, i.e., from the fast growth stage to slow growth stage. Meanwhile, the growth pattern of intestine was different between each part. In addition, the results of segmented analysis with R software showed that all of the inflexion points among three parts appeared at the age of 2 years, and their TL were 126.00 mm, 169.00 mm, 148.16 mm respectively; there were obvious differences in intestinal growth pattern among the three parts, with isokinetic growth in the foreintestine and the midintestine, but with significant allometric growth in the hindintestine, which had a fast growth stage before growth inflexion point and then changed to isokinetic growth pattern, based on the growth indices difference analysis between two stages. Thus, the difference of growth pattern of S. dabryi among the three parts of intestine might be related to their functional differentiation. Before the inflection point, the S. dabryi might improve their feeding frequency by the fast growth stage of the hindintestine, to meet the great demand for energy during the initial growth stage. The results obtained from this research can not only provide important scientific evidence for artificial cultivation of S. dabryi, but also offer a new example for studying the relationship between the growth pattern of fish intestine and its feeding habits.

     

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