ABOUT THE SPEAKER
Prosanta Chakrabarty - Ichthyologist
Prosanta Chakrabarty studies fish to help explain the evolution of human beings and our planet.

Why you should listen

Dr. Prosanta Chakrabarty is an Associate Professor and Curator of Fishes at the Museum of Natural Science and Department of Biological Science at Louisiana State University.

Chakrabarty is a systematist and an ichthyologist studying the evolution and biogeography of both freshwater and marine fishes. His work includes studies of Neotropical (Central and South America, Caribbean) and Indo-West Pacific (Indian and Western Pacific Ocean) fishes. His natural history collecting efforts include trips to Japan, Australia, Taiwan, Madagascar, Panama, Kuwait and many other countries. He has discovered over a dozen new species including new anglerfishes and cavefishes.

The LSU Museum of Natural Science fish collection that Chakrabarty oversees includes nearly half a million fish specimens and nearly 10,000 DNA samples covering most major groups of fishes. He earned his PhD at the University of Michigan and his undergraduate degree is from McGill University in Montreal. He has written two books including A Guide to Academia: Getting into and Surviving Grad School, Postdocs and a Research Job. He is also a former Program Director at the National Science Foundation. He was named a TED Fellow in 2016 and a TED Senior Fellow in 2018.

More profile about the speaker
Prosanta Chakrabarty | Speaker | TED.com
TED2016

Prosanta Chakrabarty: Clues to prehistoric times, found in blind cavefish

Filmed:
1,220,884 views

TED Fellow Prosanta Chakrabarty explores hidden parts of the world in search of new species of cave-dwelling fish. These subterranean creatures have developed fascinating adaptations, and they provide biological insights into blindness as well as geological clues about how the continents broke apart million of years ago. Contemplate deep time in this short talk.
- Ichthyologist
Prosanta Chakrabarty studies fish to help explain the evolution of human beings and our planet. Full bio

Double-click the English transcript below to play the video.

00:12
Ichthyology,
0
992
1612
00:14
the study of fishes.
1
2628
1460
00:16
It looks like a big, boring word,
2
4112
2858
00:18
but it's actually quite exciting,
3
6994
2181
00:21
because ichthyology is the only "ology"
4
9199
2973
00:24
with "YOLO" in it.
5
12196
1331
00:25
(Laughter)
6
13551
1784
00:27
Now, to the cool kids in the audience,
7
15359
1826
00:29
you already know, YOLO stands for
"you only live once,"
8
17209
4177
00:33
and because I only have one life,
9
21410
1662
00:35
I'm going to spend it doing
what I always dreamt of doing:
10
23096
2763
00:37
seeing the hidden wonders of the world
and discovering new species.
11
25883
3160
00:41
And that's what I get to do.
12
29068
1498
00:42
Now, in recent years, I really focused
on caves for finding new species.
13
30873
4455
00:47
And it turns out, there's lots of new
cavefish species out there.
14
35352
3266
00:50
You just have to know where to look,
15
38642
1783
00:52
and to maybe be a little thin.
16
40449
2209
00:54
(Laughter)
17
42682
1094
00:55
Now, cavefishes can tell me
a lot about biology and geology.
18
43800
4025
01:00
They can tell me how the landmasses
around them have changed and moved
19
48214
3983
01:04
by being stuck in these little holes,
20
52221
2218
01:06
and they can tell me about
the evolution of sight, by being blind.
21
54463
3563
01:11
Now, fish have eyes
that are essentially the same as ours.
22
59193
3277
01:14
All vertebrates do, and each time
a fish species starts to adapt
23
62494
3828
01:18
to this dark, cold, cave environment,
24
66346
2412
01:20
over many, many generations,
they lose their eyes and their eyesight
25
68782
3937
01:24
until the end up like an eyeless
cavefish like this one here.
26
72743
3150
01:27
Now, each cavefish species
has evolved in a slightly different way,
27
75917
3837
01:31
and each one has a unique geological
and biological story to tell us,
28
79778
4072
01:35
and that's why it's so exciting
when we find a new species.
29
83874
2927
01:39
So this is a new species
we described, from southern Indiana.
30
87217
3437
01:43
We named it Amblyopsis hoosieri,
the Hoosier cavefish.
31
91075
3897
01:46
(Laughter)
32
94996
1061
01:48
Its closest relatives
are cavefishes in Kentucky,
33
96081
2929
01:51
in the Mammoth Cave system.
34
99034
1602
01:52
And they start to diverge
when the Ohio River split them
35
100660
3033
01:55
a few million years ago.
36
103717
1285
01:57
And in that time they developed
these subtle differences
37
105419
2743
02:00
in the genetic architecture
behind their blindness.
38
108186
2761
02:03
There's this gene called rhodopsin
that's super-critical for sight.
39
111289
3516
02:06
We have it, and these species have it too,
40
114829
2397
02:09
except one species has lost
all function in that gene,
41
117250
2873
02:12
and the other one maintains it.
42
120147
1674
02:14
So this sets up this beautiful
natural experiment
43
122234
4023
02:18
where we can look at the genes
behind our vision,
44
126281
2964
02:21
and at the very roots of how we can see.
45
129269
2659
02:25
But the genes in these cavefishes
46
133047
1714
02:26
can also tell us
about deep geological time,
47
134785
2786
02:29
maybe no more so
than in this species here.
48
137595
2460
02:32
This is a new species
we described from Madagascar
49
140079
2817
02:34
that we named Typhleotris mararybe.
50
142920
3301
02:38
That means "big sickness" in Malagasy,
51
146245
3265
02:41
for how sick we got trying
to collect this species.
52
149534
2549
02:44
Now, believe it or not,
53
152614
1578
02:46
swimming around sinkholes
full of dead things
54
154216
2590
02:48
and cave full of bat poop
55
156830
1883
02:50
isn't the smartest thing you could
be doing with your life,
56
158737
2809
02:53
but YOLO.
57
161570
1509
02:55
(Laughter)
58
163103
3795
02:58
Now, I love this species despite the fact
that it tried to kill us,
59
166922
4174
03:03
and that's because
this species in Madagascar,
60
171120
2795
03:05
its closest relatives
are 6,000 kilometers away,
61
173939
2824
03:08
cavefishes in Australia.
62
176787
1364
03:10
Now, there's no way a three-inch-long
freshwater cavefish
63
178701
3635
03:14
can swim across the Indian Ocean,
64
182360
2039
03:16
so what we found when we compared
the DNA of these species
65
184423
2831
03:19
is that they've been separated
for more than 100 million years,
66
187278
3297
03:22
or about the time that the southern
continents were last together.
67
190599
4339
03:27
So in fact, these species
didn't move at all.
68
195875
2206
03:30
It's the continents that moved them.
69
198105
1801
03:31
And so they give us, through their DNA,
70
199930
2023
03:33
this precise model and measure
71
201977
2421
03:36
of how to date and time
these ancient geological events.
72
204422
3158
03:41
Now, this species here is so new
73
209064
2232
03:43
I'm not even allowed
to tell you its name yet,
74
211320
2483
03:45
but I can tell you
it's a new species from Mexico,
75
213827
2662
03:48
and it's probably already extinct.
76
216513
1751
03:50
It's probably extinct because
the only known cave system it's from
77
218667
3347
03:54
was destroyed when a dam was built nearby.
78
222038
2652
03:56
Unfortunately for cavefishes,
79
224714
1962
03:58
their groundwater habitat
80
226700
1580
04:00
is also our main source of drinking water.
81
228304
2196
04:03
Now, we actually don't know
this species' closest relative, yet.
82
231103
4698
04:07
It doesn't appear to be
anything else in Mexico,
83
235825
2650
04:10
so maybe it's something in Cuba,
84
238499
1700
04:12
or Florida, or India.
85
240223
2022
04:14
But whatever it is, it might tell us
something new about the geology
86
242830
4505
04:19
of the Caribbean, or the biology
of how to better diagnose
87
247359
3208
04:22
certain types of blindness.
88
250591
2121
04:24
But I hope we discover this species
before it goes extinct too.
89
252736
3410
04:28
And I'm going to spend my one life
90
256733
1915
04:30
as an ichthyologist
trying to discover and save
91
258672
3529
04:34
these humble little blind cavefishes
92
262233
2570
04:36
that can tell us so much
about the geology of the planet
93
264827
3466
04:40
and the biology of how we see.
94
268317
1816
04:42
Thank you.
95
270672
1151
04:43
(Applause)
96
271847
4359

▲Back to top

ABOUT THE SPEAKER
Prosanta Chakrabarty - Ichthyologist
Prosanta Chakrabarty studies fish to help explain the evolution of human beings and our planet.

Why you should listen

Dr. Prosanta Chakrabarty is an Associate Professor and Curator of Fishes at the Museum of Natural Science and Department of Biological Science at Louisiana State University.

Chakrabarty is a systematist and an ichthyologist studying the evolution and biogeography of both freshwater and marine fishes. His work includes studies of Neotropical (Central and South America, Caribbean) and Indo-West Pacific (Indian and Western Pacific Ocean) fishes. His natural history collecting efforts include trips to Japan, Australia, Taiwan, Madagascar, Panama, Kuwait and many other countries. He has discovered over a dozen new species including new anglerfishes and cavefishes.

The LSU Museum of Natural Science fish collection that Chakrabarty oversees includes nearly half a million fish specimens and nearly 10,000 DNA samples covering most major groups of fishes. He earned his PhD at the University of Michigan and his undergraduate degree is from McGill University in Montreal. He has written two books including A Guide to Academia: Getting into and Surviving Grad School, Postdocs and a Research Job. He is also a former Program Director at the National Science Foundation. He was named a TED Fellow in 2016 and a TED Senior Fellow in 2018.

More profile about the speaker
Prosanta Chakrabarty | Speaker | TED.com