Sea lions are sea mammals characterized by external ear flaps, long foreflippers, the ability to walk on all fours, and short, thick hair. They have an average lifespan of 20–30 years. A male California sea lion weighs on average about 300kg and is about 2.4m long, while the female sea lion weighs 100kg and is 1.8m long. The largest sea lion is Steller's sea lion, which can weigh 1000kg and grow to a length of 3.0m.