| Summary: | 碩士 === 國立海洋大學 === 漁業研究所 === 77 ===
1.By the marphological and ecological characteristics, the development it larval Sparus sarba were divided into thrse stages: (1)Prelarvae stage(TL:3-4mm)(2)Postlarvae stage(TL:4-11mm) (3)Juvenils stage(TL:11-25mm)
2.The survival rate of the starved larvae was decreased with age after their mouths opened. All larvae died at the 9th day, and their PHK(point of no return) was between the 6th and the 7th day. Loconotion duration of the fed and unfed groups began to show the differences at the end of yolk-sac stage. Total lengths of these two groups showed significant differences after their oil gloubles were absorbed. Start feeding at the 3rd day had the highest survival rate.
3.Before the netanorphosis it was pure-cone retina. (Rods were not identified until the 40th day). The larvae showed negative phototactis at 28 days old. The density ratio of total photoreceptor nuclei to the cone numbers in the was greater than 1 at the age of 35 days old. It is likely that the rods appeared before metamorphosis. The newly hatched larvae have unpigmented and presumably functionlass retinae. On the 3rd day there was sparse pigment distributed. The retinomotor responses of the pigment aigration was synchronized with the period of their netanorphosis. The acuity of larvae depended on the focal length (which increases linearly with age) and on the density of cones. During the metamorphosis, the resolving angle decrease significantly. As the larvae grew, the acuity improved.
4.The effects of light intensity on feeding behavior as follows: (1)The higher of light intensity, the higher feeding rations in larvae and juveniles, (2)Under the natural photoperiod, continuous illumination and reverse photoperiod (illumination at night). The juveniles(TL:12-15 mm) fed artenias, the young (TL:30- 40mm) fed shriap meat. Both of their feeding amount were higher in light-period, and the feeding period was changed by light. It indicated that the larvae was "visual feeder", and the activity pattern was diurnal. (3)The growth rate reared in long photoperiods (L/D=16/8) was greater than those in the short photoperiods(L/D). (4)The juveniles(TL:12-15mm) under dark adaption, feeding artemias by chance and the young(TL:28-39mm) feeding without vision was not by chance alone.
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