1
00:00:02,040 --> 00:00:07,040
Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,

2
00:00:07,080 --> 00:00:09,360
Speaker 1: I'm Lauren folk Bomb, and you and I can complain

3
00:00:09,400 --> 00:00:11,680
Speaker 1: about seasonal chills all we want, but at the end

4
00:00:11,680 --> 00:00:15,840
Speaker 1: of the day, we're basically walking furnaces. Humans are endotherms,

5
00:00:15,880 --> 00:00:19,280
Speaker 1: meaning that our bodies produce heat internally. We're also able

6
00:00:19,280 --> 00:00:22,040
Speaker 1: to maintain a body temperature that stays more or less constant,

7
00:00:22,400 --> 00:00:24,959
Speaker 1: so we should count our blessings. Not all animals have

8
00:00:25,079 --> 00:00:28,639
Speaker 1: these physiological advantages. Apart from a handful of species like

9
00:00:28,680 --> 00:00:32,280
Speaker 1: the monstrously big leather back sea turtle, very few reptiles

10
00:00:32,360 --> 00:00:34,440
Speaker 1: or amphibians are able to keep their bodies at a

11
00:00:34,440 --> 00:00:38,000
Speaker 1: constant temperature, and since they can't warm themselves up, these

12
00:00:38,000 --> 00:00:41,960
Speaker 1: creatures must extract heat from their environment. But what happens

13
00:00:42,000 --> 00:00:45,120
Speaker 1: when that environment gets colder? How to frogs, snakes, and

14
00:00:45,120 --> 00:00:47,199
Speaker 1: turtles make it through the winter months in places that

15
00:00:47,240 --> 00:00:50,720
Speaker 1: see blankets of snow, iced over lakes and subfreezing temperatures

16
00:00:50,800 --> 00:00:54,720
Speaker 1: year after year. A lot of reptiles and amphibians undergo

17
00:00:54,800 --> 00:00:59,040
Speaker 1: periods of extreme seasonal inactivity. When the weather gets colder.

18
00:00:59,200 --> 00:01:02,440
Speaker 1: They may experience decreased heart rates, slowed metabolisms, and lower

19
00:01:02,520 --> 00:01:06,679
Speaker 1: overall body temperatures. Scientists disagree over what to call this state.

20
00:01:06,920 --> 00:01:09,559
Speaker 1: Everyone accepts that it's some kind of dormancy, but while

21
00:01:09,640 --> 00:01:12,640
Speaker 1: some experts classify it as hibernation, others referred to it

22
00:01:12,680 --> 00:01:17,600
Speaker 1: as brumation. Dormant snakes generally hold themselves up in winter dens.

23
00:01:17,640 --> 00:01:20,360
Speaker 1: These shelters may take the form of an abandoned rodent burrow,

24
00:01:20,560 --> 00:01:23,319
Speaker 1: an exposed crevice on a rock face, or some naturally

25
00:01:23,319 --> 00:01:26,800
Speaker 1: occurring hole underneath a tree. Various snakes have also been

26
00:01:26,840 --> 00:01:30,840
Speaker 1: known to turnhousehold basements or garages into winter lodges in

27
00:01:30,880 --> 00:01:34,040
Speaker 1: seasonally cold areas like Canada and the northern United States.

28
00:01:34,240 --> 00:01:37,840
Speaker 1: Snakes must choose their dens with care. Ideally, a winter

29
00:01:37,880 --> 00:01:40,920
Speaker 1: hangout spot will descend below the local frost line, the

30
00:01:41,000 --> 00:01:44,600
Speaker 1: maximum depth beneath the ground at which soil freezes. Hiding

31
00:01:44,600 --> 00:01:47,240
Speaker 1: out underground is the survival strategy of choice for lots

32
00:01:47,240 --> 00:01:50,360
Speaker 1: of tortoises and turtles as well. Some species, such as

33
00:01:50,400 --> 00:01:52,960
Speaker 1: the gopher tortoise, dig their own burrows, but it's not

34
00:01:53,040 --> 00:01:56,800
Speaker 1: uncommon to find the shelled reptiles occupying pre dug unoccupied

35
00:01:56,920 --> 00:02:01,080
Speaker 1: rodent holes. Now, a hibernating lack bear can sleep for

36
00:02:01,120 --> 00:02:03,600
Speaker 1: more than one hundred days straight without consuming any food

37
00:02:03,680 --> 00:02:07,120
Speaker 1: or water. Reptiles tend to be more active during hybernation

38
00:02:07,320 --> 00:02:10,880
Speaker 1: or romation. When a midwinter warm spell comes along, they'll

39
00:02:10,960 --> 00:02:13,200
Speaker 1: use it as an opportunity to crawl up to the surface,

40
00:02:13,280 --> 00:02:15,240
Speaker 1: bask in the sunlight for a little while, and maybe

41
00:02:15,240 --> 00:02:18,720
Speaker 1: grab a quick drink. Reptiles are perceived as loaners, a

42
00:02:18,760 --> 00:02:23,200
Speaker 1: reputation that isn't entirely deserved. Consider the Eastern diamond back rattler,

43
00:02:23,400 --> 00:02:26,800
Speaker 1: who doesn't seem to mind collaborating with gopher tortoises. Members

44
00:02:26,840 --> 00:02:29,359
Speaker 1: of both species will sometimes go dormant together inside the

45
00:02:29,400 --> 00:02:34,000
Speaker 1: same burrow. Likewise, snakes often share their dens with other snakes.

46
00:02:34,440 --> 00:02:37,200
Speaker 1: Garter snakes are famous for hibernating in huge groups that

47
00:02:37,240 --> 00:02:40,560
Speaker 1: may consist of hundreds or even thousands of individuals. One

48
00:02:40,600 --> 00:02:44,160
Speaker 1: Canadian den reportedly contained no fewer than eight thousand snakes.

49
00:02:44,639 --> 00:02:47,079
Speaker 1: Indiana Jones and other videophiles will want to keep their

50
00:02:47,080 --> 00:02:51,799
Speaker 1: distance as snakes go. Garters are remarkably cold tolerant. One

51
00:02:51,840 --> 00:02:55,720
Speaker 1: species can even survive the unbelievable experience of having of

52
00:02:55,720 --> 00:02:59,080
Speaker 1: the liquid water inside its body freeze solid, but only

53
00:02:59,080 --> 00:03:01,200
Speaker 1: if it's allowed to thaw out after a few hours,

54
00:03:02,080 --> 00:03:04,600
Speaker 1: but the wood frog takes freeze tolerance to a whole

55
00:03:04,600 --> 00:03:07,920
Speaker 1: new level. A North American native, this cold weather warrior

56
00:03:08,000 --> 00:03:10,360
Speaker 1: has the distinction of being the only amphibian in the

57
00:03:10,360 --> 00:03:15,280
Speaker 1: Western hemisphere whose range extends into the Arctic Circle. Every autumn,

58
00:03:15,280 --> 00:03:18,000
Speaker 1: wood frogs bury themselves under a thin blanket of leaf

59
00:03:18,080 --> 00:03:21,079
Speaker 1: litter on the forest floor. There they will remain dormant

60
00:03:21,120 --> 00:03:24,040
Speaker 1: for up to eight months. In the process, the heart

61
00:03:24,040 --> 00:03:26,880
Speaker 1: temporarily stops beating and the frogs enter a state of

62
00:03:26,919 --> 00:03:30,160
Speaker 1: suspended animation. Left to the mercy of the elements, the

63
00:03:30,160 --> 00:03:34,640
Speaker 1: amphibians freeze at temperate and polar latitudes. Fortunately, the liver

64
00:03:34,720 --> 00:03:37,440
Speaker 1: pumps loads of glucose into the bloodstream, while urine is

65
00:03:37,480 --> 00:03:40,320
Speaker 1: retained within the body. All that helps keep the cells

66
00:03:40,320 --> 00:03:42,839
Speaker 1: from drying out, which is what would normally happen during

67
00:03:42,840 --> 00:03:47,840
Speaker 1: the freezing process. Therefore, a full six of all the

68
00:03:47,840 --> 00:03:50,360
Speaker 1: water in a wood frog's body can become frozen, and

69
00:03:50,400 --> 00:03:54,120
Speaker 1: the amphibian will still live to rib it another day. Moreover,

70
00:03:54,240 --> 00:03:56,800
Speaker 1: the frog may be kept frozen at negative eighteen degrees

71
00:03:56,800 --> 00:03:59,720
Speaker 1: celsius or about zero degrees fahrenheit, for as long as

72
00:03:59,760 --> 00:04:04,680
Speaker 1: two hundred and eighteen days. Another example of this cool

73
00:04:04,680 --> 00:04:07,880
Speaker 1: survival strategy can be found in far North Russia. The

74
00:04:07,920 --> 00:04:11,360
Speaker 1: Siberian salamander lives in areas that get temperatures of negative

75
00:04:11,400 --> 00:04:14,800
Speaker 1: fifty degrees celsius that's negative fifty eight fahrenheit or lower.

76
00:04:15,400 --> 00:04:18,920
Speaker 1: To stay alive, it hibernates underneath logs, vegetation, and snow banks.

77
00:04:19,520 --> 00:04:22,160
Speaker 1: A compound in their bloodstream keeps the critters alive when

78
00:04:22,160 --> 00:04:26,120
Speaker 1: the majority of its body water turns to ice. Terrestrial

79
00:04:26,160 --> 00:04:29,360
Speaker 1: amphibians with poor digging skills, like the wood frog, tend

80
00:04:29,400 --> 00:04:32,360
Speaker 1: to either hibernate in pre existing burrows or fine shelter

81
00:04:32,440 --> 00:04:35,919
Speaker 1: at ground level. Good burrowers, such as the American toad

82
00:04:35,960 --> 00:04:39,400
Speaker 1: and spotted salamander, proactively dig winter holes from themselves that

83
00:04:39,440 --> 00:04:44,360
Speaker 1: extend below the frost line. For aquatically inclined amphibians, there's

84
00:04:44,360 --> 00:04:48,000
Speaker 1: another option. Bullfrogs are lake and pond denizens who find

85
00:04:48,000 --> 00:04:51,080
Speaker 1: oxygen rich bodies of water and spend their winters imprisoned

86
00:04:51,160 --> 00:04:54,480
Speaker 1: under the surface of ice that forms there. Painted turtles

87
00:04:54,480 --> 00:04:58,279
Speaker 1: employ a similar strategy. Reptiles generally use their lungs to breathe,

88
00:04:58,440 --> 00:05:02,000
Speaker 1: but some semi aquatic turtles can also absorb waterborne oxygen

89
00:05:02,120 --> 00:05:06,520
Speaker 1: through their skin over wintering. Painted turtles do this extremely well,

90
00:05:06,920 --> 00:05:09,120
Speaker 1: Plus they can lower their metabolic rates to the tune

91
00:05:09,160 --> 00:05:13,720
Speaker 1: of each winter. That's how they stay alive with the

92
00:05:13,880 --> 00:05:17,040
Speaker 1: thick sheets of lake ice for months on end. Sometimes

93
00:05:17,040 --> 00:05:19,760
Speaker 1: you can even see them swimming around under the frozen barriers.

94
00:05:20,960 --> 00:05:23,440
Speaker 1: But why go through the hassle of skin breathing when

95
00:05:23,520 --> 00:05:27,160
Speaker 1: you can turn your snout into a snarkle. In January,

96
00:05:27,640 --> 00:05:30,800
Speaker 1: the Internet was greatly amused by some North Carolina alligators

97
00:05:30,960 --> 00:05:33,680
Speaker 1: whose noses were seen poking up out of a frozen pond.

98
00:05:34,360 --> 00:05:36,880
Speaker 1: Gators can't survive being trapped in icy water for much

99
00:05:36,920 --> 00:05:39,880
Speaker 1: longer than a week or so. For long term winter lodgings,

100
00:05:39,880 --> 00:05:48,080
Speaker 1: they construct deep burrows out of waterside mud. Today's episode

101
00:05:48,080 --> 00:05:50,479
Speaker 1: was written by Mark Nancini and produced by Tyler Clang.

102
00:05:50,760 --> 00:05:52,839
Speaker 1: For more on this and lots of other warm topics,

103
00:05:52,920 --> 00:06:06,520
Speaker 1: visit our home planet, how Stuff Works dot com