Did you know that the ostrich is the largest and heaviest living bird in the world? It can weigh up to 150 kg and stand up to 2.8 m tall. That's taller than most humans! Ostriches are also very fast runners, reaching speeds of up to 70 km/h. They can't fly, but they have powerful legs that can kick predators and help them escape. Ostriches belong to a group of birds called ratites, which also includes emus, cassowaries, kiwis and rheas. Ratites have flat breastbones that lack the keel that anchors the flight muscles of flying birds. They also have small wings and feathers that are…