© 1988 by The Society for Integrative and Comparative Biology
Systemic Respiratory Adaptations to Air Exposure in Intertidal Decapod Crustaceans1
Department of Biology, George Mason University Fairfax, Virginia 22030
SYNOPSIS: The responses of intertidal decapods to emersion are closely related to the particular conditions of emersion, yet all members of this group of animals face the problems of water shortage and internal hypoxia during air exposure. Several species exhibit modification of normal ventilatory activity and this response seems to enable these crabs to take up seawater from the substrate. Other crabs have specific morphological adaptations permitting recirculation of water from the exhalent apertures back into the gill chamber. The hemocyanin of some species has a higher affinity for oxygen, and this difference may be more prevalent in tropical animals. The higher oxygen affinity undoubtedly compensates in part for the lower internal oxygen tensions during air exposure. Structural specialization of the branchial apparatus may prevent the gill lamellae from adhering together, a process which reduces the surface available for gas exchange. There is a wide range of responses to emersion and yet relatively few specific adaptations. Some species are able to merely tolerate air exposure, while others are able to more fully exploit the habitat.