This could be two answers Water or Oxygen. I would go with water because it contains oxygen therefore making it a possible answer. Hope I helped. :)  
        
                    
             
        
        
        
The action or process of fertilizing an egg, female animal, or plant, involving the fusion of male and female gametes to form a zygote. The gametes that participate in fertilisation of plants are the sperm (male), and the egg cell, and in flowering plants a second fertilisation event involves another sperm cell and the central cell which is a second female gamete. In flowering plants there are two sperm from each pollen grain.
        
             
        
        
        
Answer:
Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.
 
        
                    
             
        
        
        
No they can not unlike humans and animal