Answer:
Mutualism
Explanation:
Mutualism: is a relationship between individuals of different species in which both individuals benefit from each other without causing no harm. Example is the nitrogen-fixing bacteria and plants. 
 
        
             
        
        
        
Answer: Some mammals live in water all have hair or fur.
Explanation:
 
        
                    
             
        
        
        
In terms of function, bird wings are used to flap transversely, whereas butterfly wings are used to flap laterally. In terms of structure, bird wings are filled with hollow bones for easier flight, whereas butterfly wings are structured by scales and tiny hairs.