This helps to deaden the sound of air rushing over the feathers while the bird is in flight. Also the front edge of the first primary or wing feather is toothed like a hand saw. This helps wind pass over the wings and keep the bird's flight noiseless. Some biological supply houses sell sterilized owl pellets for classroom use. These are a great way for students to investigate what types of foods owls eat.
Owls have a third, opaque eye membrane, called the nictating membrane.
This membrane helps to clean the eye of material and protect the eye from the brightness of day or foreign objects at night. Owls have four toes on each foot, like most birds. Instead of having three toes in front and one in back, an owl's outer toe is reversible - it can rotate so that there are two toes in front and two in back. At night an owl needs all the advantages they can muster to capture prey. The owl's facial disk is shaped like a shallow bowl.