Fresh water eels adaptation to Salt water

[nautica]

Anybody have any ideas on where I could find some info on this. It is for a comparitive physiology course and I believe our book was written for 3rd graders (Schmit-Neilsen, Knut) so it is not much help.

Our school library is pretty worthless, also.

Thanks
Nautica

 

[nautica]

^^^^^^^^^^^^^^^^^^^^^^

 

[Adrian]

"Most fish are confined entirely to fresh water (FW) or seawater (SW) and cannot live in or adapt to the other environment. What may be surprising is that the internal salts and organic molecules (solutes) in the blood of all bony fishes are maintained in an "intermediate" concentration (which is actually similar to that in mammals). In other words, fish in salt water may suffer stress because they are living in a medium about 3 times as salty as their blood and therefore must "pump out" extra salt that is ingested. This requires molecular transport proteins (such as the sodium/potassium pump and other ion pumps and channels). FW fish, on the other hand, face the problem of becoming "waterlogged". In other words, the higher concentrations of salts in their tissues and blood cause the fish to gain water by diffusion (also called osmosis). These fish must rid themselves of the extra water and conserve salts. They do this by using molecular transport proteins. In general the control of internal salt and water balance (osmoregulation) requires significant metabolic energy to power it. As most people know, a small number of fish like salmon and eels spend a part of their life in FW and part of their life in SW. These fish literally switchover from the FW metabolism to the SW metabolism, a process that may be metabolically stressful. (...)"
from: http://www.fastlane.nsf.gov/servlet/showaward?award=0111860

Just google for "eels osmoregulation" or "fresh salt water osmoregulation fish" ;)

 

[Adrian]

http://www.csuchico.edu/~pmaslin/ichthy/xcrtn.html

That's a nice overview over osmoregulation, with two basic sketches halfway down the page.

 

[nautica]

cool, thanks