parshanut torah comment - Inconsistency in listing creeping things in Noach's Ark's population

The animal population of Noach's Ark is commanded/listed six times in Parashat Noach:

1. 
   

   Genesis 6:19-20 (Initial command)

   
   


2. 
   
   

   Genesis 7:2-3 (Reiteration of command)

   
   


3. 
   

   Genesis 7:8-9 (Entry to the Ark)

   
   


4. 
   

   Genesis 7:14-16 (Reiteration of entry)

   
   


5. 
   

   Genesis 8:17 (Command to exit)

   
   
   


6. 
   

   Genesis 8:19 (Exit)

   
   

Each of these lists include animals, birds, and creeping things, except the second, which omits creeping things. Why?

Answer

The second one which does not mention creeping things is dividing the types into pure and impure, where pure animals and pure birds were brought in pairs of seven, and impure animals and impure birds were brought in twos. Creeping things were not so divided. Although there are pure creeping things none are appropriate (or really practical) as sacrifices which was the point of the extra amounts of pure fauna.