Blood glucose in marine Penaeid Prawns. III. Variation in relation to ovarian growth in Parapenaeopsis Hardwickii (Miers) (Crustacea,Decapoda, Penaeidae)

In the present study on female Parapenaeopsis hardwickii information is presented concerning the variation in blood glucose concentration during the different stages (I to V) of ovarian growth. A direct proportionality was found between blood glucose level and ovary growth. There was an incessant hike in blood glucose level as ovary development proceeds from stage I to IV but a drastic downfall was noticed in stage V, i.e. in the spawned prawns. Physiological significance of these findings are discussed.This study was supported by I.C.A.R., New Delhi, India through a Project on Reproductive Endocrinology of Edible Prawns     

Studies on the behaviour and substratum preference in juveniles of the marine prawn,Metapenaeus monoceros (Fabricius)

Circadian rhythmicity in the behaviour of the marine prawn, Metapenaeus monoceros (Fab) and its substratum preference has been observed under laboratory conditions. In the morning at 9. a.m. 80% prawns remain buried and in the afternoon at 3 p.m. 60% burrowing was observed. A contrasting situation was observed in the night i.e. 17% burrowing at 9 p.m. and 30% burrowing at 3 a.m. was registered. In the second set of experiments juveniles were subjected to four types of substrata viz. mud, black fine sand, white coarse sand and stones. It was noted that M. monoceros showed more affinity towards the mud and less preference to other substrata. The obtained results are discussed to provide clues for prawn fishing.This work was supported by I.C.A.R., New Delhi through a project on Reprod. Endocr. Edible prawns.     

Observations on the hatching process and salt and water regulation in the embryos of the freshwater snail Indoplanorbis exustus

The freshwater snail Indoplanorbis exustus laid its eggs in triple layers in a gelatinous, ribbon shaped matrix. Hatching was by mechanical means. The capsular membrane of the embryos was more permeable to water than to other organic and inorganic ions.     

Survival of the marine crab,scylla serrata exposed to thermal shock under different experimental conditions

Survival of the edible crab, Scylla serrata Subjected to endocrinological and pharmacological procedures, was examined after exposing them to 40°C for 3 hr. Only normal, intact crabs could withstand the thermal shock but not reserpinized intact, eyestalkless, sinus glandectomised (SGE), SGE and reserpinized (RSP), SGE injected with sinus gland homogenate and SGE injected with SG homogenate and reserpinized crabs. The possible involvement of endocrine centres in S. serrata in sustaining the environmental thermal shock is discussed.     

Role of brain hormone in oogenesis of the Indian freshwater leech,Poecilobdella viridis (Blanchard) during the annual reproductive cycle

The possible role of a brain hormone in oogenesis of Poecilobdella viridis has been investigated by brain extirpation and brain extract injections during non-reproductive (November to January) and reproductive (March to May) periods. Brain extirpation during the non-reproductive period ceased maturation of the ovary. It is inferred that brain secretion bears possibly a gonadotropic principle which governs and regulates the oogenesis during the annual reproductive cycle.     

Reproductive ecology of the marine pulmonate,onchidium verruculatum

O. verruculatum shows aggregated spatial dispersion during the pre-reproductive and reproductive period, which appears to be closely related with propagative requirements. Analysis of the stomach contents and laboratory observations indicate that O. verruculatum feeds on marine sea weeds (Padina and Ulva).     

Reproductive biology of the indian freshwater leech,Poecilobdella viridis (Blanchard)

Annual reproductive cycle of the protandrous hermaphroditic freshwater leech, Poecilobdella viridis has been traced from August 1974 to July 1975. Spermatogenesis initiated a little earlier than oogenesis. The reproductive programme is as follows; commencement of spermatogenesis in February followed by oogenesis in March. Breeding begins in late March extending upto late May and early June while breeding terminated towards late June. From August to January reproductive quiescence was observed. Among the environmental factors temperature, possibly coupled with photoperiod, plays a key role in synchronising the reproductive cycle.