摘要
在实验条件下观察了克氏原螯虾的幼体发育。详细描述了第一至第三龄幼体发育的形态特征。
Procambarus clarkii originated in the north of Mexico and the south of America, was introduced into China by Japanese in the 1930s, and now distributes in more than 10 provinces. In some regions, it has become a predominant species and is one of the main aquatic products of China. This paper describes the larwal development of this orayfish under laboratory condition from February 1992 to July 1993. The changes in the morphological features from the first to the third instar wre observed and detailed illustrations including their appendages are shown. The body segments of the crayfish have basically accomplished their development in the egg stage. So, there is no metamorphosis in the larval development. The first instar larva has a body length of about 46mm. The cephalothorax is very large, occupying over one half of the body length, and contains rich yolk inside. Eyes are sessile and immobile. There are neither first and fifth aabdominal appendage nor the uropod. The second instar larva is about 67mm long. The cephalothorax is much less swollen, retaining a little yolk. Stalked eyes can move freely. The uropods are present and protrude, making the telson distinctly trilobed. It can walk and swim and begins to feed. The third instar larva is about 92mm long and looks like an adult. The first abdominal appendages are present. At this stage of development the larva is fully capable of living apart from the mother. Based on the observation that the third instar larva has basically accomplished the development of external structures completely absorbed the yolk, and begins to move freely and feed, it is reasonable to consider development before the third instar as larval development, whereas that from 4 11th instar as juvenile crayfish development. The duration of larval development is affected by water temperature. In normal condition (about 25 ℃), the first instar about 5 days, the second instar 7 days,and the third instar 8 days. However, below 15 ℃, the larva hardly grows and develops. Besides water temparature,forage also affects the duration of larvaldevelopment. Rich feed can accelerate growth and development of the larva, and vice versa.
出处
《动物学报》
SCIE
CAS
CSCD
1997年第4期372-381,共10页
ACTA ZOOLOGICA SINICA
