QUESTION:
How can penguins dive as far as they can, and withstand the pressure?

        Mike P., 15
        Lewiston Alternative Middle School
        Lewiston Idaho

ANSWER from Donna Patterson, Research Assistant, Dr. Fraser's Team
            Palmer Station, Antarctica
            Sun, 9 Mar 1997 14:24:34 -0500

Hello Mike, 

Penguins are able to dive as deep as they can by using a number of 
adaptations that are specific to feeding in the sea.   Most Antarctic 
penguin species dive to depths of 100 meters, although Emperors 
can dive as deep as 300-500 meters.   As you descend from the surface, 
the pressure increases and has a compressing effect on the birds.   
Their bodies are adapted to allow for this compression:  gas  within 
the lungs will compress and  abdominal air sacs will also shrink without 
harming the penguin.   Penguins have also changed the way that they 
use oxygen underwater which helps keep nitrogen levels low enough 
that they do not have problems that people do when coming up from the 
dives (the "bends").

Thanks for your question!
Donna