Morphometric features and proximate body composition of rocky freshwater prawn (Caridina africana, Kingsley 1882) at Erin-Ijesa waterfalls, Osun State Nigeria

An investigation was conducted on the morphometric features and proximate body composition of rocky freshwater prawn, Caridina africana occurring at Erin-Ijesa Waterfalls in Osun State, Nigeria. The adult prawns were collected at the first layer of the Waterfalls using scoop nets and locally fabricated sieves because of the shallow nature of the water body and tiny size of the species. Morphometric features were measured using measuring board and Vernier calipers while the proximate analysis was determined by atomic absorption spectrophotometry in the laboratory. The morphometric variables placed the species correctly into the Infra order Caridea and family Atyidae because the first and second chelipeds were shorter than the remaining three pairs of walking legs. Male prawns were significantly bigger (p<0.05). than the females as revealed in the morphometric features. The proximate analysis showed that C. africana is composed of 58.79% protein, 5.42% lipid, 11.56% carbohydrate, 14.7% ash and 0.21 % crude fibre. The micro-nutrient composition included iron, zinc, copper, nickel and cadmium. The values for these nutrients make the study to suggest that C. africana could be a nutritive food bio-material for humans and other livestock nutrition especially the fin-fish aquaculture programme

Economy of mate attraction in the Cassin's finch

Mate attraction can be costly. Thus, individuals should modulate it according to its probable benefits. Specifically, individuals should modulate mate-attraction efforts based on their need for, the probability of attracting, and the reproductive competence of prospective mates. We tested these predictions by monitoring song output in laboratory-housed male Cassin's finches (Carpodacus cassinii) before, during and after brief female exposure following variable periods of isolation from females. We inferred individual reproductive competence from the product of season and reproductive schedule, the latter estimated from moult progress. Males produced little song in the presence of a female but robustly elevated song output in response to female loss. However, mere absence of a female did not elevate song output in males unaccustomed to female proximity. Furthermore, song output in response to female loss increased with her reproductive competence. We suggest that individuals modulate mate-attraction effort based on the benefits such efforts are likely to yield