Laboratory observation on spawning,fecundity and larval development of amphioxus (Branchiostoma belcheri Tsingtaunese)

Although amphioxus is widespread in temperate and tropical seas, its population is diminishing because of environmental pollution. To keep the population of this evolutionarily important animal from diminishing, study on its reproduction and development is necessary. The main findings in this study on the spawning and fecundity of the amphioxus reared in laboratory and its larval development are as follows. 1. Water temperature markedly affected the spawning. It spawned only when water temperature reached 21°C. 2. Spawning of the amphioxus in laboratory was markedly extended. Initially, the amphioxus spawned at about 7:00 PM, but spawning time was postponed as spawning days went on. 3. The number of eggs produced by a female ranged from 1400 to 12800, average of 5800. This also represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time. 4. During the first few months of life of the amphioxus, its growth rate changed seasonally. The growth rate in summer and fall was greater than that in winter. 5. The pelagic larva became a benthic adult after 50 days. 6. The amphioxus reared in laboratory from fertilized eggs could produce fertile eggs and sperms. These findings can be a foundation for measures to address the problem of diminishing amphioxus population. Contribution No. 2274 from the Institute of Oceanology, Chinese Academy of Sciences This work was supported by CNNSF, and Chinese Academy of Sciences.     

Artificial culture of amphioxus (Branchiostoma belcheri tsingtauense)

Mature amphioxus (Branchiostoma belcheri tsingtauense) collected by trawl in June, 1994 from Qingdao Shazikou sea area bottom sands, were cultured under controlled indoor conditions, where they spawned and their eggs were fertilized and hatched into larvae which gradually settled at the bottom and dug into the sands after 40-50 days culture in a water trough outdoors. The total survival rate of the larvae(LSR)was 5.5% before they went into the sands, 1.9% in 4 months, 0.7% in 10 months. The survival rate of the young fish which had dug into the sands (YSR) was 35.6% in 4 months, and 12.6% in 10 months. The amphioxus number tended to be constant from the 11th month on. In the first five months after incubation, the amphioxus body length increased by an average of about 1.5 mm a month, and about 0.4 mm a month from Dec. to May of next year. The maximum length after ten months was 24 mm; the average was about 11 mm. After two years culture in the water trough, the maximum length could reach 34-35 mm, when the amphioxus gonads began to develop.     

海鞘与文昌鱼谁更接近脊椎动物的始祖

脊椎动物的起源是进化生物学研究的核心问题之一,目前人们普遍认为脊椎动物与无脊椎动物中的脊索动物起源于同一个原始祖先。头索动物文昌鱼和尾索动物海鞘是现存的无脊椎动物中和脊椎动物亲缘关系最近的类群,是研究胚胎发育机制和脊索动物统进化的典型材料。长期以来,文昌鱼一直被认为是脊椎动物的姊妹类群,比尾索动物海鞘更接近于脊椎动物。但最近的研究却有了相反的观点,这导致了脊索动物进化历程之争,引起人们广泛的兴趣和关注。本文介绍这两类原索动物的研究现状,并对它们的进化地位以及作为研究脊椎动物起源的模型进行了探讨。     

温度和盐度对青岛文昌鱼胚胎发育的影响

青岛文昌鱼的胚胎在 18℃以上才能正常发育 ,并随着温度的升高而加快 ,但超过34℃胚胎解体 ,低于 14℃发育受阻。正常胚胎发育的盐度范围是 2 1～ 33,最适盐度为 2 4 .5～ 30 .2。     

昌黎县海洋环境承载力评估研究

选取昌黎县海岸线人工化指数、海域开发资源效应指数、海水水质等指标构建昌黎县海洋资源环境承载力评价指标体系,采用专项评价和综合评价相结合的方法,对河北省昌黎县资源环境承载力进行评估研究。结果表明,受入海悬沙量变化和入海污染物的影响文昌鱼栖息地遭到严重破坏,海洋生态承载状况为严重超载,因此需要采取控制污染源,加强监管等手段来改善文昌鱼生长环境压力。     

厦门国家级自然保护区厦门文昌鱼资源及其保护

根据2001年4月－2002年3月在厦门文昌鱼（Branchiostoma belcheri)自然保护区进行4个季度月的文昌鱼资源调查资料，估算保护区内文昌鱼现有资源量约有27.6t，分析了影响文昌鱼生存的不利因素，并对保护区管理与保护提出建议。     

厦门文昌鱼自然保护区的生态环境特点

根据2001年4月～2002年3月在厦门文昌鱼（Branchiostoma belcheri）自然保护区进行4个季度月的环境监测资料整理而成。结果：本调查海域水动力相对较强,水体中溶解氧、化学耗氧量、pH值等项目的测定结果均符合一类海水水质标准。表层沉积物属氧化的沉积环境,未受有机质污染。分析了保护区内环境现状,为保护区的管理和保护提出若干建议。     

从无脊椎动物到脊椎动物的纽带——头索动物文昌鱼

头索动物文昌鱼是现存的最接近脊椎动物的无脊椎动物,它的形体结构简单却具有脊索动物的基本特征,而且其没有经过大规模复制的基因组结构与脊椎动物的始祖很接近。文昌鱼占据着重要的进化地位,并且长期以来在进化生物学和发育生物学等研究领城中一直作为模式动物,本文从文昌鱼的发现、形态结构、物种及分布、生活习性和胚胎发育等方面作以阐述。     

LABORATORY OBSERVATION ON SPAWNING,FECUNDITY AND LARVAL DEVELOPMENT OF AMPHIOXUS (BRANCHIOSTOMA BELCHERI TSINGTAUNESE)

Although amphioxus is widespread in temperate and tropical seas,its population is diminishing be-cause of environmental pollution.To keep the population of this evolutionarily important animal fromdiminishing,study on its reproduction and development is necessary.The main findings in this study onthe spawning and fecundity of the amphioxus reared in laboratory and its larval development are as fol-lows.1.Water temperature markedly affected the spawning.It spawned only when water temperature reached 21℃.2.Spawning of the amphioxus in laboratory was markedly extended.Initially,the amphioxus spawned at about 7:00 PM,but spawning time was postponed as spawning days went on.3.The number of eggs produced by a female ranged from 1400 to 12800,average of 5800.This al-so represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time.4.During the first few months of life of the amphioxus,its growth rate changed seasonally.Thegrowth rate in summer and fall was greater than that in     

Production of fertile eggs and sperms in laboratory-reared amphioxusBranchiostoma belcheri tsingtaunese

Althoug hamphioxus has been studied embryologically for over 130 years, little is known concerning the gonadal development of the laboratory-reared animal. The present study in which the amphioxus were sucessfully maintained in the laboratory for more than one year showed that they could produce fertile eggs and sperms like their wild counterparts. Project (39470091) supported by NSFC and partially by Shandong Natural Science Foundation Grant 93D0140.