Osmoregulation in Adelie Penguins

     Adelie Penguins (shown in video below) live in Antarctica, with no access to fresh water.  Their diet is largely made up of marine invertebrates, mostly krill.  Because these penguins require lower salt concentrations in their bodies than their surroundings, they need to regulate the levels of salt and water in their cells, or their osmotic concentration.  This is called osmoregulation.

       An Adelie penguin's salt levels are lower than that of its environment, and this causes a concentration gradient that favors the influx of salt.  They also must drink salt water to obtain the water they need.  In order to get rid of the extra salt, the penguins developed a mechanism called the salt gland.  The salt gland lies in the skull of the penguins.

     This picture from http://digimorph.org/specimens/Pygoscelis_adeliae/ shows where the salt glands are located in the skull of the Adelie Penguin.  Salt diffuses into blood cells, and salt ions (Na⁺ and Cl^-) in the blood are removed by the sodium transport mechanism (the sodium potassium pump).  These salt ions are moved to the salt glands where they are secreted into a highly concentrated salty solution and "sneezed out" by the penguins.
     Salt glands are also found in other marine birds, marine reptiles, and sharks.  Without them these organisms would not be able to drink saltwater without becoming dehydrated. 


Information from:
https://elibrary.unm.edu/sora/Auk/v114n03/p0488-p0495.pdf
http://www.cartage.org.lb/en/themes/sciences/zoology/animalphysiology/osmoregulation/osmoregulation.htm