their muscles are always at a temperature for maximum performance... 肌肉始终保持在最佳性能的温度
Mammals had a long way to go to become masters of the world's oceans, 哺乳动物想要成为海洋的主宰 还有很长的路要走
Twice the length of a great white shark. 身长是大白鲨的两倍
The mammals' journey into the oceans was a gradual one. 哺乳动物进入海洋的过程是渐进式的
these fruit bats are in a race to return to the roost... 这些果蝠竞相返回巢穴