Simplify the following text for a Grade 11 native English-speaking person.
Original: The fur of most species is brownish in color , often with a white underbelly , but many other patterns exist , especially in the cricetine and arvicoline subfamilies .
Simplified: Most species have brown fur , with a white colored underbelly , but there are also many other patterns , especially in the cricetine and arvicoline subfamilies .