The hippopotamus, despite its stocky appearance and short legs, is actually one of the most dangerous animals in Africa. Weighing up to 4,000 pounds (1,800 kg), these massive semi-aquatic mammals can run surprisingly fast—up to 30 km/h (19 mph) on land for short bursts. They are highly territorial in water and can be extremely aggressive, often attacking boats and even crocodiles. Despite being herbivores, they have powerful jaws capable of opening up to 150 degrees, delivering a bite force of about 1,800 psi—stronger than a lion's.