Gas Exchange

Water enters the gill chamber at the base of the cheliped like in all other crabs. The water that passes through this entrance is filtered by setae which sit at the base of the chelipeds, a feature that all benthic crabs have to remove sediments from the inhalant flow. A current is created by the gill bailer which pulls water into the inhalant chamber. Once there, water flows across the gill filaments and then through to the exhalant chamber. The water then exits anteriorly through exhalant apertures. In summary the water that passes through the branchial chamber follows a U shape, entering in the posterior direction and exiting anteriorly after passing through the gill filaments, (see Figure 17.) Gas exchange occurs by diffusion across a very thin cuticle, to the deoxygenated blood supplied by veins. Clibanarius longitarus in particular, like many other anomurans, have plate-like lamellae gill filaments, (see Figure 17.) The gill filaments in decapods are cleaned by elongated epiopods of the three maxillipeds, which sweep the filaments of any foreign particles, (Ruppert, Fox & Barnes, 2004.)

Figure 17- (left) Diagram showing the flow direction of water through the gill chamber. (right) Diagram of the gill lamellae found in in the Blue striped hermit crab. (Diagrams modified from Ruppert, Fox & Barnes, 2004, by Author, 2014)