1)
What are "Dalsei Panav"?
1.
'Rashi': Its lips. When it closes its mouth, who can open it?!
2.
Ibn Ezra: Its mouth.
3.
Malbim: Its lips and jaws.
2)
What fear is around its teeth?
1.
'Rashi': No creation can approach its teeth, due to fear of it.


