IDENTIFICATION OF INLAND FRESHWATER CRAB SPECIES NICHE AND BIOLOGY: A CASE STLDV OF WETLANDAVATERSHED AREA IN MINNA ENVIRONS

Abstract

ABSTRACT Survey was carried out to identify burrows/holes of crabs in three (3) sites covering three hectares of watershed field in the Main campus of Federal University of Technology, Minna. Two hundred and seven (207) burrows/holes of crabs were identified and 60 were dugged out to collect the crabs, 20 holes per site and 5 holes per sampling in each site, the length of burrows measured between 21.1-95 cm deep. Fifty- five (55) crabs were collected, the size of crab varies comprising of (nymphs (10), juvenile (10) and adult (35(fifteen male, twenty female)) indicating their reproductive and growth activities. The crabs were observed resting at the entrance of the burrows at dawn and dusk (6- Sam and 6-8pm). They withdrew to the hole quickly on perceiving any strange sound or movement. Standard chart was used to identify the species. Species identified is Afrithelphosa monodoso Matured male were morphologically different from female, though the size and shape are the same, female have club on their antenna and possess porch at the anterior end. The matured females were gravid between April-May, with oval small eggs of 10 cm diameter, orange in color 10-20 eggs, clustered and stringed in each porch. The eggs were laid in between May and June, in late June, female porches were emptied indicating the egg were laid. At commencement of rains, the eggs hatched under favorable conditions of more rainfall which provided moist and reduces temperature of the soil. The soil became water logged and burrows filled with water. The commencement of rainfall motivates them to bring out fresh soil cast outside the entrance of the burrows indicating there is a crab residing in that burrow in most cases. They feed vigorously during rainy season and hibernate in dry season. This study shows that crabs ecology and biology has the potentials of being cultured for their great nutritional and resourceful value. Keywords: Crabs, Wetlands, Niche and Biology.