Subject: Whale, Eye size
Tue, 11 Mar 1997 11:13:46 GMT+1200

Date:          Sun, 9 Mar 1997 17:15:31 -0500 (EST)
To:  ,,
Subject:       Blue Whale Eyes

My daughter is researching whales for a project in school.  She would like to
know the size of a blue whale's eye.  Thank you.

I don't study physiology but I'll give it my best shot.  Vision generally doesn't play an 
important a role in whales because visibility under water is so much poorer than on land.  
Thus, whales have relatively small eyes compared to their body size.  Nevertheless their 
eyes are pretty big.  Right whale eyes are about the size of an orange, while blue whales 
eyes are probably  one and a half times bigger.   

To function at all, whale and dolphin eyes have to undergo adaptations to their aquatic 
environment.  For instance, they don't need to keep their eyeballs wet (because they are 
already in water) so they lack lacrymal glands (those glands that produce tears).  In other 
words whales can't cry.  They also need not worry about dust  and so don't have eyelashes.  
The smallest cetacean eye is that of the Ganges river dolphin.  This dolphin feeds off the 
muddy bottom of rivers where eyesight doesn't help much.  Its eye is really small, about as 
big as a pea.  

Nathalie Patenaude
Molecular Ecology and Evolution Group
School of Biological Sciences
Private Bag 92019
University of Auckland
Auckland, New Zealand

Ph:  649 373 7599 ext 4588
Fax: 649 373 7417