1
00:00:00,430 --> 00:00:05,769
In this video we are going to learn about cold-blooded and warm-blooded animals.

2
00:00:08,480 --> 00:00:15,000
Cold-blooded animals are those that have a body temperature that is the same as the temperature of the environment.

3
00:00:15,800 --> 00:00:20,500
For instance, this snake is in a place at 10 degrees Celsius.

4
00:00:21,559 --> 00:00:26,079
This means the body temperature of the snake will be also 10 degrees Celsius.

5
00:00:26,079 --> 00:00:31,079
If I take the snake to a place at 50 degrees,

6
00:00:31,079 --> 00:00:35,079
now the snake will change the body temperature,

7
00:00:35,079 --> 00:00:37,079
it will be affected by the environment,

8
00:00:37,079 --> 00:00:42,079
and with time the snake will also be at a body temperature of 50 degrees.

9
00:00:42,079 --> 00:00:46,079
But then this means that the snake,

10
00:00:46,079 --> 00:00:49,079
being at the same temperature as the environment,

11
00:00:49,079 --> 00:00:52,079
may be extremely warm.

12
00:00:52,079 --> 00:01:00,119
So, cold-blooded animals have a body temperature like that of the environment, and this means they are not always cold.

13
00:01:01,140 --> 00:01:05,760
This means cold-blooded is not an appropriate term for these animals.

14
00:01:05,980 --> 00:01:08,879
Scientists prefer to call them ectotherms.

15
00:01:09,560 --> 00:01:11,400
Ecto means outside.

16
00:01:12,099 --> 00:01:16,819
This means the temperature of these animals is like the temperature of the outside.

17
00:01:17,659 --> 00:01:20,760
Most animals are ectotherms.

18
00:01:20,760 --> 00:01:26,099
The animals that are not ectotherms are birds and mammals.

19
00:01:27,099 --> 00:01:30,719
Birds and mammals are warm-blooded animals.

20
00:01:31,459 --> 00:01:39,900
Warm-blooded means that their body temperature may be different from the temperature of the environment.

21
00:01:41,260 --> 00:01:48,120
So, as an example, here we have an eagle in a place at a temperature of 10 degrees Celsius.

22
00:01:48,120 --> 00:01:53,120
But the body temperature of the eagle is going to be 40 degrees.

23
00:01:53,120 --> 00:01:57,120
That is the normal temperature for a bird, 40 degrees.

24
00:01:57,120 --> 00:02:02,120
It does not matter it is in a place at 10 degrees Celsius.

25
00:02:02,120 --> 00:02:09,120
It is a warm-blooded animal and it means its body may keep a temperature independent from the place.

26
00:02:09,120 --> 00:02:17,120
So if the place is at 10 degrees, the body temperature may still be at 40 degrees.

27
00:02:17,120 --> 00:02:25,620
If I take the eagle to a place at 50 degrees, the eagle is able to keep its body temperature.

28
00:02:25,620 --> 00:02:30,419
This means the body temperature of the eagle will stay at 40 degrees.

29
00:02:30,419 --> 00:02:37,419
Even if the place is at 50 degrees, the eagle keeps a body temperature of 40 degrees

30
00:02:37,419 --> 00:02:44,419
because these animals may keep a temperature different from that of the environment.

31
00:02:44,419 --> 00:02:52,539
This means that scientists prefer to call warm-blooded animals endotherms.

32
00:02:53,219 --> 00:03:02,639
Endo means inside, so the temperature does not depend on the outside, it only depends on the inside.

33
00:03:03,680 --> 00:03:10,340
And, as I said before, the only animals that are endotherms are birds and mammals.

34
00:03:10,340 --> 00:03:18,759
Now, what is the advantage and disadvantage of all this?

35
00:03:18,759 --> 00:03:26,759
So, endotherms, and remember this means birds and mammals, always have a very good body temperature.

36
00:03:26,759 --> 00:03:28,759
They have the body temperature that they need.

37
00:03:28,759 --> 00:03:33,759
In case of birds, they need 40 degrees and their body is always at 40 degrees.

38
00:03:33,759 --> 00:03:37,759
We mammals do not need such high temperature.

39
00:03:37,759 --> 00:03:41,759
For us, 36-37 degrees is okay.

40
00:03:41,759 --> 00:03:50,759
So these animals, birds and mammals, always have a very good body temperature but the problem is that this requires a lot of energy.

41
00:03:50,759 --> 00:03:56,759
Birds and mammals need a lot of energy and this means they need a lot of food.

42
00:03:56,759 --> 00:03:59,759
Birds and mammals need a lot of food.

43
00:03:59,759 --> 00:04:08,759
The animals that are cold-blooded and the proper term is ectotherms, this means all the other animals that are not birds and mammals,

44
00:04:08,759 --> 00:04:15,759
These animals, the ectotherms, need to be in an environment with the appropriate temperature.

45
00:04:15,759 --> 00:04:20,759
Since their temperature cannot be different from that of the environment,

46
00:04:20,759 --> 00:04:24,759
what they do is they move to the environment that has the appropriate temperature.

47
00:04:24,759 --> 00:04:28,759
If they do not find such an environment, they will not have a good temperature.

48
00:04:28,759 --> 00:04:34,759
Perhaps their body will not be able to move properly, because the cells will not be at a good temperature.

49
00:04:34,759 --> 00:04:40,759
But they have an advantage. The advantage is that they consume very little energy.

50
00:04:40,759 --> 00:04:47,759
And this means that they need much less food in comparison to endotherms.

51
00:04:47,759 --> 00:04:55,759
So the eagle is an endotherm. It is a warm-blooded animal. It needs a lot of energy.

52
00:04:55,759 --> 00:05:00,759
Its temperature is always good, independently from the temperature of the environment.

53
00:05:00,759 --> 00:05:04,759
But it needs a lot of food. Eagles need to eat every day.

54
00:05:04,759 --> 00:05:09,759
The snake is a cold-blooded animal. The snake is an ectothern.

55
00:05:09,759 --> 00:05:17,759
This means it needs to move to the appropriate environment always to have a good temperature.

56
00:05:17,759 --> 00:05:20,759
But it consumes very little energy.

57
00:05:20,759 --> 00:05:27,759
Snakes need very little food. Many snakes eat only once every three months.

58
00:05:27,759 --> 00:05:34,660
only okay so the eagle needs to eat every day the snake does not need to eat

59
00:05:34,660 --> 00:05:41,560
every day if there is no food the eagle is going to die much earlier than the

60
00:05:41,560 --> 00:05:43,860
snake