Published online by Cambridge University Press: 05 June 2012
Introduction
Most vertebrates cannot survive more than a few minutes without any oxygen. As pointed out in Chapter 1, the high intrinsic rate of oxygen consumption of the brain makes it one of the first organs to fail in anoxia. While medical science struggles to find ways to counteract anoxic tissue damage, unfortunately with quite limited success, evolution has solved this problem a few times, as revealed by the few vertebrates that can survive months without any oxygen. The best-studied examples of such anoxia-tolerant vertebrates are the crucian carp (Carassius carassius) and some North American freshwater turtles in the genera Trachemys and Chrysemys.
It is not a coincidence that these extremely anoxia-tolerant vertebrates are aquatic. The access to oxygen may be temporarily halted in many aquatic habitats, either because water oxygen content becomes severely depleted (see Chapters 1 and 5), or because lung breathers such as turtles lose their access to air for long periods, especially during overwintering. A particularly longlasting and extreme oxygen depletion occurs in many small, ice-covered lakes and ponds in the northern hemisphere. Due to a thick ice cover, which blocks oxygen diffusion as well as light needed for photosynthesis, these waters may become anoxic for several months (Holopainen and Hyvärinen, 1985; Ultsch, 1989). It is under such conditions that crucian carp and turtles have evolved their ability to survive long periods of anoxia.
To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.