苏氏(鱼芒)的鳔的形态结构和气呼吸习性

THE MORPHOLOGICAL STRUCTURE OF THE SWIM BLADDER OF PANGASIUS SUTCHI AND ITS AIR-BREATHING

本文研究了苏氏(鱼芒)的鳔的形态结构和气呼吸习性。苏氏(鱼芒)的鳔呈高度血管化和具有密集的类似肺泡的泡囊状呼吸小室。通过水面的气呼吸活动获得氧气。在水温为25.2—25.8℃、溶氧量0.57—0.65mg/l时,气呼吸频数为17.2—17.5次/鱼/小时。呼吸频数随溶氧量升高而下降。在高溶氧量的水体中(3.45—5.46mg/l)仍具有进行水面气呼吸,但频数较低。在阻碍气呼吸进行时,窒息点为0.95—1.06mg/l,这一窒息点大大高于气呼吸时正常生活所允许的最低溶氧量(约0.6mg/l)。实验证实了鳔是苏氏(鱼芒)的重要辅助呼吸器官。

The present paper deals with the morphological structure of the swim bladder and air-breathing in Pangasius sutchi (Fowler), a freshwater catfish introduced from Thailand into China in 1978. The swim bladder of P. sutchi is a well vascularized vesicular organ with closely concentre respiratory cells like lung-aviolus. In normal condition, the fish goes to the water surface and exchanges gases with the atmosphere to get oxygen at intervals. The air-breathing frequency is determined to be 17.2-17.5 per fish. hr. when the dissolved oxygen content is 0.57-0.65 mg/l, temperature is 25.2-25.8℃, The frequency decreases as the level of dissolved oxygen content in water increases. At high level of dissolved oxygen content in water (3.45 -5.46 mg/1), air-breathing still exists, but less frequently. When surfacing activity is prevented, the suffocation point is 0.95-1.06 mg/1, which much higher than the lowest dissolved oxygen content to sustain life as air-breathing is kept. The swim bladder is confirmed to be an important accessory respiratory organ which makes the fish great adaptability to the circumstances. Such a special organ is scarely found in catfish.