java Template for class fields -

i have 3 classes different fields:

class cow(){ private integer legs; private integer eyes;}  class fish(){ private integer fins; private integer eyes;}  class pinguin(){ private integer legs; private integer fins; private integer eyes;} 

i want make sure fields valid / allowed fields. there design pattern ? if use inheritance animal() cow may have fins want avoid. want fins called fins , not 'fin' or 'fiins' in subclass. suggestion ?

this basic object oriented design. follow real world close possible. create base class animal() subclasses birds(), mammals(), insects() , on. go further down in tree.