Who looks to Hashem for food?
Radak: All lower creations. You created them and their food. Even so, every day they look to You to give to them their food - "Nosen Lechem l'Chol Basar" (136:25), through a chain of causes. You can give to them or withhold from them. Even though they do not have Da'as to know Who gives and prepares, their nature is to look for their daily rations. We know that they look to You, for You give and prepare.
Why does it say "b'Ito" (singular)?
Kesuvos 67b: "Atah Nosen Lahem Es Achlam b'Ito 1 " (145:15) teaches that Hashem gives to each one his food in his time.
Radak: Each species has a known time at which Hashem prepares its food.
Malbim: He gives to each when it needs it.
That is a different verse, but presumably we can derive this also from our verse. (PF)
