that continuously pumps blood across their lungs... 能够持续将血液送至肺部
as it was for their prehistoric ancestors. 对于其史前祖先也是如此
Crocodiles can slow their heart rate to just two beats a minute... 鳄鱼能够将心跳降至每分钟两次
...wildebeest come to quench their thirst. 对危险毫无知觉
and find the perfect spot to lay their eggs. 并找到完美的产蛋地点
they come together in their thousands. 它们成千上万结伴而来
adult females must still return to dry land to lay their eggs. 每年仍要返回干燥的陆地上产卵
turtles went back to the seas their ancestors left, 海龟回到了祖先曾离开的大海
was when some of them turned their back on the land 也许是其中一些动物放弃陆地