The sneakiest tricksters of the animal kingdom - Eldridge Adams

643,903 views ・ 2018-12-18

TED-Ed


Please double-click on the English subtitles below to play the video.

00:07
A male firefly glows above a field on a summer’s night,
0
7001
3920
00:10
emitting a series of enticing flashes.
1
10921
3030
00:13
He hopes a nearby female will respond with her own lightshow
2
13951
3560
00:17
and mate with him.
3
17511
1230
00:18
Sadly for this male,
4
18741
1660
00:20
it won’t turn out quite the way he plans.
5
20401
3100
00:23
A female from a different species mimics his pulsing patterns:
6
23501
4570
00:28
by tricking the male with her promise of partnership,
7
28071
3020
00:31
she lures him in–
8
31091
1510
00:32
and turns him into an easy meal.
9
32601
2460
00:35
He’s been deceived.
10
35061
2220
00:37
Behavioral biologists have identified three defining hallmarks of deception
11
37281
5005
00:42
by non-human animals:
12
42286
2220
00:44
it must mislead the receiver,
13
44506
2070
00:46
the deceiver must benefit,
14
46576
1970
00:48
and it can’t simply be an accident.
15
48546
2740
00:51
In this case we know that the predatory firefly’s signal isn’t an accident
16
51286
4524
00:55
because she flexibly adjusts her flash pattern
17
55810
3180
00:58
to match males of different species.
18
58990
3090
01:02
Based on this definition,
19
62080
1570
01:03
where is animal deception seen in nature?
20
63650
3590
01:07
Camouflage is a good starting point–
21
67240
2250
01:09
and one of the most familiar examples of animal trickery.
22
69490
3870
01:13
The leaf-tailed gecko and the octopus fool viewers
23
73360
3700
01:17
by blending into the surfaces on which they rest.
24
77060
3370
01:20
Other animals use mimicry to protect themselves.
25
80430
3185
01:23
Harmless scarlet kingsnakes have evolved red, yellow, and black patterns
26
83615
4760
01:28
resembling those of the venomous eastern coral snake
27
88375
3570
01:31
to benefit from the protective warnings these markings convey.
28
91945
4530
01:36
Even some plants use mimicry:
29
96475
2008
01:38
there are orchids that look and smell like female wasps to attract hapless males,
30
98483
5870
01:44
who end up pollinating the plant.
31
104353
2880
01:47
Some of these animals benefit by having fixed characteristics
32
107233
3490
01:50
that are evolutionary suited to their environments.
33
110723
3440
01:54
But in other cases,
34
114163
1310
01:55
the deceiver seems to anticipate the reactions of other animals
35
115473
4080
01:59
and to adjust its behavior accordingly.
36
119553
2890
02:02
Sensing a threat,
37
122443
1100
02:03
the octopus will rapidly change its colors to match its surroundings.
38
123543
4560
02:08
Dwarf chameleons color-match their environments more closely
39
128103
3709
02:11
when they see a bird predator rather than a snake–
40
131812
3140
02:14
birds, after all, have better color vision.
41
134952
3440
02:18
One of the more fascinating examples of animal deception
42
138392
3000
02:21
comes from the fork-tailed drongo.
43
141392
2820
02:24
This bird sits atop tall trees in the Kalahari Desert,
44
144212
3850
02:28
surveying the landscape for predators and calling when it senses a threat.
45
148062
4550
02:32
That sends meerkats, pied babblers, and others dashing for cover.
46
152612
5010
02:37
But the drongo will also sound a false alarm
47
157622
2810
02:40
when those other species have captured prey.
48
160432
3020
02:43
As the meerkats and babblers flee,
49
163452
2480
02:45
the drongo swoops down to steal their catches.
50
165932
3680
02:49
This tactic works about half the time–
51
169612
2410
02:52
and it provides drongos with much of their food.
52
172022
3580
02:55
There are fewer solid cases
53
175602
1360
02:56
of animals using signals to trick members of their own species,
54
176962
4094
03:01
but that happens too.
55
181056
1840
03:02
Consider the mantis shrimp.
56
182896
2049
03:04
Like other crustaceans,
57
184945
1402
03:06
it molts as it grows,
58
186347
1760
03:08
which leaves its soft body vulnerable to attack.
59
188107
3440
03:11
But it’s still driven to protect its home against rivals.
60
191547
3900
03:15
So it has become a masterful bluffer.
61
195447
3180
03:18
Despite being fragile,
62
198627
1580
03:20
a newly molted shrimp is actually more likely to threaten intruders,
63
200207
4790
03:24
spreading the large limbs it usually uses to strike or stab its opponents.
64
204997
5511
03:30
And that works –
65
210508
1213
03:31
bluffers are more likely to keep their homes than non-bluffers.
66
211721
4740
03:36
In its softened condition,
67
216461
1515
03:37
a mantis shrimp couldn’t withstand a fight–
68
217976
2520
03:40
which is why we can be confident
69
220496
1840
03:42
that its behavior is a bluff.
70
222336
2170
03:44
Biologists have even noticed that its bluffs are tactical:
71
224506
3966
03:48
newly molted mantis shrimp are more likely to bluff against smaller rivals,
72
228472
5030
03:53
who are especially likely to be driven away.
73
233502
3530
03:57
It would seem that instead of just threatening reflexively,
74
237032
3270
04:00
the mantis shrimp is swiftly gauging the situation and predicting others’ behavior,
75
240302
4890
04:05
to get the best result.
76
245192
2080
04:07
So we know that animals can deceive,
77
247282
2090
04:09
but do they do so with intent?
78
249372
2000
04:11
That’s a difficult question,
79
251372
1610
04:12
and many scientists think we'll never be able to answer it.
80
252982
3350
04:16
We can't observe animals’ internal thoughts.
81
256332
2780
04:19
But we don’t need to know what an animal is thinking in order to detect deception.
82
259112
4930
04:24
By watching behavior and its outcomes,
83
264042
2430
04:25
we learn that animals manipulate predators, prey, and rivals,
84
265885
4760
04:30
and that their capacity for deception
85
270645
2120
04:32
can be surprisingly complex.
86
272765
3050
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7