Question

When birds dive into water to catch fish, they usually dive straight down. Explain why.

Answer 1

To catch fish, birds usually dive straight down to avoid misconception of vision due to refraction.

When light passes from a rarer to a denser medium, it bends away from the normal. Due to this, the fish would not appear to be at the position where they really are, instead, they would appear raised or bent. However, when the fish are viewed from an angle of 90° (from the normal), their position visible would be accurate. Hence, to catch their prey with precision, birds dive straight down.