I WONDER - Why Do Birds Have Hollow Bones? Me Pregunto - Por Qué Las Aves Tienen Huesos Huecos?

The video explains how hollow bones make birds lighter and aid in flight, while also being part of the respiratory system for efficient breathing. Despite being hollow, bird bones are strong and dense, allowing them to withstand flight movements. Penguins, however, have dense bones to help them dive, as they do not fly.

In what way are the bones of birds described as strong despite being hollow?

Why do some birds, like penguins, not have hollow bones?