| The wild T.septentrionalis were taken as the research object in this article,we analyzed its external form and sperm ultrastructure,The experiment takes the larvae of T.septentrionalis as sample to observe and record its morphologic change.At the same time,we refer to the anthropometric data of the juvenile fish breeded in factory farming pond for guidence.In the last,we make and analyzed the karyotype of T.septentrionalis.Aimed at providing basis data of T.septentrionalis' development characteristics and the information of fish species' form.Experiment 1 A total number of 131 T.septentrionalis(total length20.20~36.55 cm,weight range 88.82~806.30g)were collected from Yellow Sea as experimental samples.We then observed its external form and drew the description in vivo.We then measured the outer form of the fish body,and The linear regrassion analysis of morphological features were carried out,The number of dorsal fin rays,caudal fin rays,anal fin rays,pectoral fin rays were also counted;we then prepared its chromosome specimens by hot titration method,and then analyze the chromosome karyotype.The results indicated that: First,T.septentrionalis has a flat oval body.When alive,the head and back of the body is in pewter and the abdomen is in a whitish turquoise color.After death,the color of the T.septentrionalis darkens into a dark green,The fins remain turquoise is the obvious feature of their external morphology.Second,Body length is 1.5~3.3 times as long as body height;Body length is 3.1~4.9 times as long as head length;The head length is 1.1~1.6 times as long as Proboscis length;Third,the variation of total length/standard length was minimum and the difference between female and male was the lowest,the correlation equation was Sl = 0.0203Tl2-0.1539 Tl +12.76(R2 =0.96),which had the best linear correlation coefficient,female: Sl = 0.0066 Tl2+ 0.499 Tl + 5.0597(R2 =0.96),male: Sl=0.0279Tl2-0.5034Tl+16.73(R2=0.96).The calculation of Caudal length/Caudal depth,Standard length/Caudal length,Head length/Eye diameter and Head length/Eye interal had the lowest linear correlation coefficient,and the variation and difference between female and male were the highest.Fourth,The general correlation equation of standard length and weight is W = 0.3351Sl2+ 14.699Sl-261.59(R2 = 0.72);W =-0.1729Sl2 + 33.919Sl-444.47(R2=0.73)for male ones,W=2.5919Sl2-78.288 Sl + 694.91(R2=0.80)for female ones.Fifth,Fin type: dorsal fin?,36~39;Anal fins 34~37;Tail fins 14~15;The pelvic fin degenerate into pelvic fin spines.Sixth,The surface of the body is covered with a variety of fleece scales,each piece of scale consists of a base plate and a bony bulge;Lateral lines are composed of trunk line infraorbital line.Experiment 2 To study the ultrastructure of the spermatozoa of T.septentrionali,its external form and Crosscutting structure were observed by scanning and transmission electron microscopy.The spermatozoa of T.septentrionali consisted of a head and a tail.The head,without acrosome,is shell-shaped,of which the main structure was nucleus.Its caudal end there was an implantation fossa.The implantation fossa was deep,with the depth of 5/6 to the head length.The nucleus consisted of electron dense chromatin materials,with a head pit and nuclear vacuole whose chromatin was free.The centriolar compound of midpiece is situated in the implantation fossa which consists of three parts: the proximal centriole,the intercentriolar and basal body.The proximal centriole and the basal body were arranged at an orthogonal,and in“T” structure,while the basal body was parallelled to the spermatozoa.The sleeve was very deep,the deepest point was just 1/3 to the head.The implantation fossa shaped like a rod.The sleeve is behind the nucleus which contains five to six mitochondria arranged in a circle.There were few of ellipse vesicles in the sleeve outside mitochondrion.The structure of the flagellum was accommodated for the spermatozoa move.The main structure of the tail was axoneme,which was slim and long.The structure of the tail was of the typical “9+2” model.The flagella was fine,and there were none lateral fins on the flagellum.This paper reveals the morphological structure of its spermatozoa,in order to enrich the physiological contents of teleosts,and provide the basis for the identification of the fish species.Experiment 3 Take the larvae of T.septentrionalis as the sample,which hatched in the same season.We then observe and record its morphologic change.In the meanwhile,we record the growth characteristics of T.septentrionalis' larvae under industrial farming conditions.Based on ecological method,one month old juvenile filefish were cultured for 10 months with sea water temperature at 11.08?~26.32?.In the meantime,growth features of juvenile filefish were recorded.The results indicatedthat: First,the average body weight and average total body length of the one month old juveniles increased from(0.07±0.02)g and(1.59±0.33)cm to(143.20±10.32)g and(20.31±0.67)cm,with the maximum average weight gain(44.15±5.74)g/month,average weight gain(0.48±0.04)g/d.Second,there was a linear relationship between the total length and days age: L= 0.0693x+0.3017(R2= 0.9468),with the body length instantaneous growth ratio of 0.008.There was a power function relationship between body weight and total length: W= 0.014L3.0479(R2=0.9968),with the power close to3.0,which indicated that body weight was positively related to the cube of total length and the juveniles performed isometric growth.Both the length of the first dorsal fin and body height had a linear relationship with the total length.Fourth,under industrial farming conditions,the body weight gain and instantaneous growth ratio were in concordance with the fluctuation of sea water temperature,The increment of body weight was high at 18.52~26.32?.The study indicated that T.septentrionalis has better growth performance in warm sea water.It is a promising high-grade warm water aquaculture species.Experiment 4 30 tail of T.septentrionalis' larvae(Total length 9.0cm)were take as the experimental samples,We then prepared the T.septentrionalis chromosome specimens by hot titration method,and then analyzed the chromosome karyotype,also discussed the evolution degree of T.septentrionalis.Set up three repeating group,each group of ten fish.Fry with 0.0075% colchicine final concentration of seawater temporarily keep 4 h,each group randomly take 3 tails,shearing pectoral gills the preparation of chromosome specimen.In the end,the chromosome karyotype analysis showed that T.septentrionalis chromosome number is 2n=40,karyotype is 2n=40T. |
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