Yolk utilization and hatching time in the Canadian lobster Homarus americanus

During the course of its embryonic development, the Canadian lobster Homarus americanusMilne-Edwards exhibits steady increases in water content (56.2 to 86.8%) and ash (5.8 to 21.2%), and a progressive decrease in energy content from 6636 to 4292 cal/g dry weight. Mean dry weight of a single egg is 965 μg, equivalent to 6.4 cal; a freshly hatched egg. The lobster hatches about 1,500 larvae per night over a period of 4 to 5 days. Dry weight, ash and calorific contents of larvae hatched on different days show considerable variations. After larvae hatch on the first day, continuous salt absorption by eggs to hatch on subsequent days leads to a steady increase in ash content from 143 μg/larva hatched on the first day to 255 μg/larva hatched on the fourth day, and consequently, to an increase in dry weight from 854 to 956 μg/larva. Metabolism of embryos (0.1 cal/day), which are yet to be hatched on subsequent days, depletes the calorific content per unit weight (from 4637 to 3837 cal/g dry weight) as well as per larva (from 3.98 to 3.67 cal)

Scope for commercial culture of tilapia

The suitability of tilapia species for fish culture and the potential for the development of commercial culture operations in India are discussed. Sex regulation, monosex tilapia polyculture, chromosome manipulation and sex reversal, nutrition and feed formulation are examined in detail

Ecological energetics of the grasshopperPoecilocerus pictus in Bangalore fields

The structure and biomass ofPoecilocerus pictus population in four fields in Bangalore were estimated by direct observation method. Results on the density ofP. pictus, the survivorship curve of the grasshopper and the growth of the population are reported. The data on feeding rates, assimilation and conversion obtained in the laboratory were applied to the size and structure of theP. pictus populations in the different fields to estimate the rate and efficiency of energy flow through the population. The results indicate the defensive mechanism developed by the plant against predation. Efficiencies of exploitation, assimilation and production by the populations averaged 3·4, 34 and 15% respectively. Factors like predation, food and space do not appear to regulate the size of the population. Probably it is controlled by intrinsic population factors

Ecological energetics of the grasshopper Poecilocerus pictus in Bangalore fields

The structure and biomass of Poecilocerus pictus population in four fields in Bangalore were estimated by direct observation method. Results on the density of P. pictus, the survivorship curve of the grasshopper and the growth of the population are reported. The data on feeding rates, assimilation and conversion obtained in the laboratory were applied to the size and structure of the P. pictus populations in the different fields to estimate the rate and efficiency of energy flow through the population. The results indicate the defensive mechanism developed by the plant against predation. Efficiencies of exploitation, assimilation and production by the populations averaged 3·4, 34 and 15 respectively. Factors like predation, food and space do not appear to regulate the size of the population. Probably it is controlled by intrinsic population factors. © 1979 Indian Academy of Sciences

Freshwater prawn farming trials in Bangladesh

Details are given of pond trials conducted in Bangladesh regarding the culture of freshwater prawn (Macrobrachium rosenbergii ). Integrated rice and prawn farming systems were also experimented and results indicated that the prawn could be a suitable species for such integration. Such systems, pond or integrated, are suggested to be best practiced in the southeastern and southwestern areas of the country where there is tidal water exchange and post-larvae are naturally available

Techniques to produce 100 percent male tilapia

A discussion is presented on endocrine sex reversal and chromosome manipulation techniques for producing 1005 male tilapia. Details are given of methods for the administration of steroids and the induction of ploidy

Techniques to produce 100 percent male tilapia

Sex reversal, Hormones Oreochromis aureus, Oreochromis mossambicus

Freshwater prawn farming trials in Bangladesh

Prawn culture, Aquaculture techniques, Integrated farming, Bangladesh, Macrobrachium rosenbergii

Unknown metabolic inhibitor contained in the brain of starved frog Rana hexadactyla

The O consumption of brains from frogs starved for 60 days was examd. Brain and liver from well-​fed frogs consumed 400.8 and 309.9 μl of 0​/g​/hr, resp. The resp. values for starved subjects were 213.8 and 67.7 μl. of 0​/g​/hr. Adding exts. of starved tissue to well-​fed tissue decreased greatly the O consumption of the latter. Exts. from well-​fed brain added to starved ext. increased the activity of the latter significantly. Thus, there may be a metabolic inhibitor in the brain of starved frogs and a stimulating factor in the brain of well-​fed frogs

Genetic, abiotic and social influences on sex differentiation in cichlid fishes and the evolution of sequential hermaphroditism

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73799/1/j.1467-2979.2005.00184.x.pd