Studies On Reproductive Development And Fluorescent Marking Technology Of Cuttlefish Sepia Esculenta (Cephalopoda: Sepiidae)

This paper reviewed the recent literatures on the biology and enhancement technique of Sepia esculenta, including morphology, fishery biology, behavior ecology, and genetics. The domestication and propagation behaviour in artificial environment, the histology observations on gonad and oogenesis, the growth and digestive enzymes, the development of retina, the feeding behavior in different environmental factors, the fluorescent marking technology were studied in this paper. The most results are summarized as follow.1 Studies on the domestication and the propagation behaviour in cuttlefish, Sepia esculenta (Cephalopoda:Sepiidae)S.esculenta were collected from Rizhao Lanshan as researchful object in this paper. The matching and reproduction behaviour of mature S. esculenta were observed in breeding pond, the effect of different spawning substrate were studied, the relationship between the mantle length and body weight of S.esculenta and fecundity was analyzed, the spawning rhythm of mature S.esculenta was founded. The investigation results showed that the courtship behaviour, chasing behaviour, matching behaviour, spawning behaviour were obviously observed in the process of mating; there were significantly differences-between different spawning substrate, compared with the Kochia scoparia substrate, The fishing net substrate and Tamarix chinensis substrate are better; there were no founction relation between the fecundity and he mantle length and body weight of S.esculenta, the fecundity was mostly between 500 and 1500, and the average was 1114;the spawning time was very disciplinarian and mostly between 21:00 and the next day 03:00.2 Histology observations on gonad and oogenesis in cuttlefish, Sepia esculenta (Cephalopoda:Sepiidae)Sepia esculenta, is a most commercially important species of coastal fishes in China and Japan,however, little is known about the mature reproductive system, the gonadal development and the oogenesis of cultured juveniles. To determine the histological character of the mature reproductive system and the juveniles size at gonadal differentiation, five adults (3 females,2 males) cuttlefish and 39 cultured juveniles ranging from 1 to 88 d old after hatching are used in this experiment. The results show that S.esculenta is gonochorism and the genital system of the males consists of spermary, spermaduct, vesicular seminalis, prostate gland and Needham's Sac.The Needham's Sac is completely filled with tightly packed and well developed spermatophores. The spermatophore is shaped like a baseball bat and consists of an elongated sperm mass, a cement body, a coiled spring-like ejaculatory organ, and a cap. Sperm mass are "V"-like stored in the cavity of spermatophore from longitudinal section. From the transverse section, they are seen spirally stored in the spermatophore especially near to the centre. The genital system of the females consists of ovary, oviduct, albumen gland and affiliated gland.The time that gonads are differentiated into ovaries in juveniles is at about 7th d after hatching when the gonads contained some staining gonocytes. Eight stages of oocytes were indicated basing upon the degree of formation and development of the oocytes and associated follicle cells via the histological observation.3 Studies on growth and digestive enzymes of juvenile cuttlefish, Sepia esculenta (Cephalopoda:Sepiidae)The S.esculenta were collected from Rizhao Lanshan as researchful object in this paper, the oosperms of natural collection and manul collection were hatched under the artificial condition, the hatchlings were reared with superfluous food everyday, the developmental characteristic of S.esculenta was studied and the relation between age and developmental parametey was analyzed.The investigation results showed that the temperature significantly affected the oosperm hatching time; the oosperm hatching rate was not significantly affected by temperature, but significantly affected by salinity; the survival rate of S.esculenta was 81.4% in small water, and 100% in big water; the autotomy was not appearance when the foods were eough, the size of S.esculenta was in order and the density of S.esculenta was low; the hatchlings grow rapidly with the development. The acid protease activity and the activity of lipase of S.esculenta were increasing with ages, which werel58.3 U/mL and 183.2 U/mL respectively when they were 210d old after hatching. 4 Development of the retina in the cuttlefish, Sepia esculenta (Cephalopoda: Sepiidae)To provide morphological bases for functional studies, the development of the photoreceptor cells in the retina of a cuttlefish, Sepia esculenta from newly hatched juveniles to the adults, was examined by light-and electron-microscopy. Four layers can be distinguished in the retina according to the observation.1),rhabdomeric layer. Which increases in thickness gradually during the development. On the lateral surface of the growing apical processes in the rhabdomeric layer, microvilli increase in length and regularity.In longitudinal sections of the apical processes, the microvilli are arranged at right angles to the long axis of each apical process, but the top of the apical process is often free from microvilli. In cross-sections, the microvilli arise radially in all directions from the round circumference of the apical process. Usually the pigment granules coming from microvilli are crowded near the distal end and base of the process, gradually increase in number, often form a large aggregation. Some microvilli start to decay as more and more vesicles coming from microvilli. 2), sub-rhabdomeric layer. There exist numerous pigment granules, a few mitochondria, sparsely scattered small vesicles of various shapes, golgi apparatuses, and myeloid bodies. At first they are very few and small, and then increase in number,In the eyes of newly hatched juveniles, the number of the nucleus in the sub-rhabdomeric layer is very large, but decreases much with the development as they ceaselessly pass through the basal lamina into the inner-segment. The supporting cells increase in number and send out very long microvilli into the rhabdomeric layer, the electron-lucent of the whole the sub-rhabdomeric layer is increasing.3), inner segmental layer. They are rich in membranous organelles. The cytoplasm contains microtubules and numerous free ribosomes. Mitochondria increase in number remarkably.4),plexiform layer. Which consists of the receptor cell axons, nerve fibers, mitochondria, golgi apparatuses, and the glial cells. With the development of the retina, the structure of plexiform layer become stronger. Morphometric data on the rhabdomeric microvilli from the newly hatched to the adult retinas are presented. The thickness of the rhabdomeric layer and the total surface area of the rhabdomeric microvilli present beneath a unit surface area of the retina show a logarithmic increase with developmental days, the diameter of lens shows a linear increase with days. The results of our research show that the visual acuity and sensitivity of S.esculenta continuously increased with the development.5 Effects of different environmental factors on feeding behavior of juvenile cuttlefish, Sepia esculenta (Cephalopoda:Sepiidae)This paper investigated the effects of substrate(glass substrate,sand substrate),visual angle(frontage,above,below) on feeding behavior of sepia escul-enta. The results in the present study indicated that substrate significantly affected the feeding behavior of Sepia esculenta,and covert behavior could easily be seen in the process of Sepia esculenta's feeding behavior in sand substrate. There were no significant differences between 2501x and 0.11x; the chance of successfully preying the shrimp which is above the view is about 20% lower than o-ther bearings; the reaction distance of Sepia esculenta(doral mantle length, DML (43mm,48mm,56mm))is 130.0cm,135.5cm,143.1cm respectively in 2501x;and 115.0cm,120.6cm,126.3cm in 0.11x.6 The study of fluorescent marking technology in cuttlefish Sepia esculenta (Cephalopoda:Sepiidae)It is very important to establish a kind of simple and useful marking method to evaluate multiplication and releasing effect and the current situation of fisheries resource. The golden cuttlefish were chosen to be the study matieral in this article. The larval golden cuttlefish hached after 15d were immersed in 6.0～8.0×10-3% alizarin complexone(ALC)for 24h. The tagged group and control group were reared in 1.5m×1.5m×1.5m indoor pond for 30d, and then they were removed to 2667m2 outdoor pond. After 60d, their mean doral mantle length grew to 91.4mm (control group) and 87.6mm (tagged group) respectively, they were removed to indoor pond for over winter. During 210d experiment, the golden cuttlefish were sampled randomly in order to examine the growth and the dye-retention of the tagged cuttlebone after tagged 15,30,45,60,90,210d. The results of the experiment showed that this marking method is very effective, and the survival rate of the tagged golden cuttlefish is 100%. There are no significant differences between the growth of the tagged group and the control group (P>0.05). The half tagged lavender ring is very clear in the cuttlebone even after tagged 210d. Additionally, according to this method, we could tag lots of samples easily in one time, and the retention of marker can last long period. Due to the maneuverability and easy to distinguish tagged ones, it is suggested that this method could be a good marking method for golden cuttlefish.