Md. Rabiul Islam*
Department of Zoology, A.N. College, Dumka, Jharkhand, India
Received : 21st May, 2023 ; Revised : 24th June, 2023
DOI:-https://doi.org/10.5281/zenodo.12640568
Abstract– The freshwater crab, Paratelphusa spinigera is abundantly found in/on the mud soil of the bank of Kawar Lake Wetland. These crabs live in the coastal littoral zone of the wetland having shallow water. These are not only aquatic but also terrestrial in habit and crawl on the land and take their food. These animals are not only aquatic but also terrestrial in habit and respire bimodally. The respiratory circulation was investigated in the bimodally breathing crab Paratelphusa spinigera by analysis of the distribution of carmine solution injected into the haemocoel. The gills and branchial membrane (branchiostegite and membranous thoracic walls), both trap this carmine solution. The main blood supply to the branchiostegites is from the venous sinuses, which shows its involvement in gas exchange. In the air-breathing crab a greater proportion of the total venous return is directed to the branchiostegite. The air- haemolymph barrier in the branchiostegite was found to be 3.232 μm. Paratelphusa spinigera has seven pairs of phyllobranchiate gills contained in the branchial chamber. From central axis of the gills arise bilaterally situated thin flaps, the lamellae. The afferent branchial vessel (the epibranchial vessel) is located on the dorsal side of the gill arch and the efferent vessel (the hypobranchial vessel) on the ventral side. Between these two blood vessels the blood percolates through the lamellar vascular channels, where it is oxygenated. The lamellae consist of an epithelial cell layer covered by thin cuticle. The epithelial cells approach each other at regular intervals and fuse in the middle of lamellar sinus delineating the vascular channels.
Key words: Freshwater crab, Paratelphusa spinigera, branchiostegite membrane, counter current principle\
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