Sloths! The strange life of the world's slowest mammal | Lucy Cooke — Transcript

Full transcript

1. 0:12Hello.
2. 0:14Well, I'm here to talk to you about my animal muse:
3. 0:19the sloth.
4. 0:20(Laughter)
5. 0:23I've been documenting the strange lives of the world's slowest mammal
6. 0:27for the last 10 years.
7. 0:29I still remember the first time I saw one.
8. 0:31I was fascinated by their freaky biology.
9. 0:36I mean, what's not to love about an animal that's born
10. 0:39with a fixed grin on its face?
11. 0:41(Laughter)
12. 0:43And the need to hug.
13. 0:45Audience: Awww.
14. 0:47But sloths are massively misunderstood.
15. 0:52They've been saddled with a name that speaks of sin
16. 0:55and damned for their languorous lifestyle,
17. 0:58which people seem to think has no place amongst the fittest
18. 1:02in the fast-paced race for survival.
19. 1:05Well, I'm here to tell you that we've got this animal all wrong --
20. 1:10and how understanding the truth about the sloth
21. 1:13may help save us and this planet we both call home.
22. 1:19I traced sloth-based slander
23. 1:22back to a Spanish conquistador called Valdés,
24. 1:26who gave the first description of a sloth in his encyclopedia of the New World.
25. 1:31He said the sloth was
26. 1:33"the stupidest animal that can be found in the world ...
27. 1:36I have never seen such an ugly animal or one that is more useless."
28. 1:42(Laughter)
29. 1:43Tell us what you really think, Valdés.
30. 1:45(Laughter)
31. 1:47I'd like to have a word about Valdés's drawing skills.
32. 1:51(Laughter)
33. 1:53I mean, what is that?
34. 1:56(Laughter)
35. 1:58I've never seen an illustration of a sloth that's more useless.
36. 2:01(Laughter)
37. 2:02But I mean, on the plus side,
38. 2:04he has given the sloth a remarkably humanlike face,
39. 2:06and sloths do have remarkably humanlike faces.
40. 2:10This sloth I photographed in Costa Rica, I think looks a lot like Ringo Starr.
41. 2:16(Laughter)
42. 2:17But then, sloths do bear an uncanny resemblance to the The Beatles.
43. 2:22(Laughter)
44. 2:26Particularly pleased with Paul, actually, on there.
45. 2:31But like The Beatles, sloths are also extremely successful.
46. 2:36They come from an ancient line of mammals, and there were once dozens of species
47. 2:40including the giant ground sloth, which was the size of a small elephant
48. 2:44and one of the only animals big enough to eat avocado pits whole
49. 2:49and disperse them.
50. 2:51So ... (Laughter)
51. 2:53Some of you have worked it out already.
52. 2:55(Laughter)
53. 2:56That means that without sloths,
54. 2:58there might be no avocado on toast today,
55. 3:01leaving hipsters everywhere totally bereft at breakfast.
56. 3:05(Laughter)
57. 3:07(Applause)
58. 3:13Today, there are six surviving species, and they fall into two groups.
59. 3:17You've got your Bradypus three-toed sloths,
60. 3:19they're the ones with the Beatles haircuts and the Mona Lisa smiles.
61. 3:24Then, there are the two-toed sloths.
62. 3:27They look a little bit more like a cross between a Wookiee and a pig.
63. 3:31They live in the jungles of Central and South America,
64. 3:34and they're extremely prolific.
65. 3:36There was a survey that was done in the 1970s
66. 3:39in a Panamanian tropical forest
67. 3:41that found that sloths were the most numerically abundant large animal.
68. 3:46They took up one quarter of the mammalian biomass.
69. 3:50Now, that's an awful lot of sloths
70. 3:53and suggests they're doing something very right indeed.
71. 3:58So what if, rather than deriding the sloth for being different,
72. 4:05we tried to learn from it instead?
73. 4:09We humans are obsessed with speed.
74. 4:13Busyness is a badge of honor,
75. 4:15and convenience trumps quality in our quest for quick.
76. 4:20Our addiction to the express life is choking us and the planet.
77. 4:26We idolize animals like the cheetah, the "Ferrari of the animal kingdom,"
78. 4:32capable of doing naught to 60 in three seconds flat.
79. 4:36Well, so what?
80. 4:38(Laughter)
81. 4:42(Applause)
82. 4:46So what?
83. 4:47The sloth, on the other hand,
84. 4:48can reach a leisurely 17 feet a minute
85. 4:52with the wind behind it.
86. 4:54(Laughter)
87. 4:57But being fast is costly.
88. 4:59The cheetah is speedy, but at the expense of strength.
89. 5:03They can't risk getting in a fight,
90. 5:05so they lose one in nine kills to tougher predators like hyenas.
91. 5:09No wonder they're laughing.
92. 5:11(Laughter)
93. 5:12The sloth, on the other hand,
94. 5:13has taken a more stealthy approach to dinner.
95. 5:16They survive by capturing and consuming
96. 5:20static leaves.
97. 5:22(Laughter)
98. 5:24But you see, leaves don't want to be eaten any more than antelope do,
99. 5:27so they're loaded full of toxins and very hard to digest.
100. 5:31So in order to consume them,
101. 5:32the sloth has also had to become an athlete --
102. 5:36a digesting athlete.
103. 5:38(Laughter)
104. 5:39The sloth's secret weapon is a four-chambered stomach
105. 5:42and plenty of time.
106. 5:44They have the slowest digestion rate of any mammal.
107. 5:47And it can take up to a month to process a single leaf,
108. 5:51which gives their liver plenty of time to process those toxins.
109. 5:55So, sloths aren't lazy.
110. 6:00No, they're busy.
111. 6:02Digesting.
112. 6:04(Laughter)
113. 6:05Yeah, really busy.
114. 6:07(Laughter)
115. 6:09Hard at work, that sloth, very hard at work.
116. 6:12And of course, leaves have little calorific value,
117. 6:15so sloths have evolved to spend as little energy as possible.
118. 6:19They do about 10 percent of the work of a similar-sized mammal
119. 6:23and survive on as little as 100 calories a day,
120. 6:27thanks to some ingenious adaptations.
121. 6:31The Bradypus, three-toed sloths,
122. 6:32they've got more neck bones than any other mammal,
123. 6:35even a giraffe.
124. 6:36Which means they can turn their head through 270 degrees
125. 6:41and graze all around them,
126. 6:43without having to actually bother with the effort of moving their body.
127. 6:47(Laughter)
128. 6:50It also means that they are surprisingly good swimmers.
129. 6:53Sloths can bob along in water
130. 6:56three times faster than they can move on land,
131. 6:59kept afloat by ...
132. 7:01trapped wind.
133. 7:03(Laughter)
134. 7:05So --
135. 7:06(Laughter)
136. 7:07sloths are the only mammal that we know of that don't do flatulence.
137. 7:11When they need to expel gas,
138. 7:13it's actually reabsorbed into their bloodstream
139. 7:16and expelled orally as a sort of mouth fart.
140. 7:19(Laughter)
141. 7:23Turning their lives upside down saves further energy.
142. 7:27They have about half the skeletal muscle of a terrestrial mammal.
143. 7:31They don't really have so many of the extensor muscles
144. 7:35that are the weight-bearing muscles;
145. 7:37instead, they rely on retractor muscles to pull themselves along.
146. 7:41They have long, hooked claws and a high fatigue resistance,
147. 7:45so they can literally hook on and hang like a happy, hairy hammock
148. 7:50for hours on end.
149. 7:52And sloths can do almost anything in this inverted position.
150. 7:56They sleep, eat and even give birth.
151. 7:59Their throat and blood vessels are uniquely adapted
152. 8:02to pump blood and to swallow food against the force of gravity.
153. 8:06They have sticky bits on their ribs
154. 8:09that prevent their enormous stomach from crushing their lungs.
155. 8:13And their fur grows the opposite direction,
156. 8:16so they can drip dry after a tropical drenching.
157. 8:20The only problem is, if you turn a sloth the other way up,
158. 8:25gravity removes its dignity.
159. 8:28Audience: Awww.
160. 8:30They can't hold themselves upright.
161. 8:32And so they drag their bodies along as if mountaineering on a flat surface.
162. 8:37And I think this is why the early explorers like Valdés
163. 8:40thought so poorly of them,
164. 8:42because they were observing sloths the wrong way up and out of context.
165. 8:48I've spent many happy hours mesmerized by moving sloths.
166. 8:53Their lack of muscle hasn't impeded their strength or agility.
167. 8:57Nature's zen masters of mellow move like "Swan Lake" in slow mo --
168. 9:03(Laughter)
169. 9:04with the core control of a tai chi master.
170. 9:08This one has fallen asleep mid-move, which is not uncommon.
171. 9:13(Laughter)
172. 9:17But you're probably wondering:
173. 9:19How does a dangling bag of digesting leaves avoid being eaten?
174. 9:23Good question.
175. 9:24Well, this is one of the sloth's main predators.
176. 9:26It's the harpy eagle.
177. 9:28It can fly at speeds of up to 50 miles per hour,
178. 9:31has talons the size of a grizzly bear's,
179. 9:34razor-sharp eyesight,
180. 9:35and that ring of feathers focuses sound
181. 9:38so that it can hear the slightest leaf rustle.
182. 9:41The sloth, on the other hand, has poor hearing, bad eyesight,
183. 9:46and running from danger is clearly not an option.
184. 9:50No, they survive by wearing an invisibility cloak
185. 9:54worthy of Harry Potter.
186. 9:56Their fur has grooves that attract moisture
187. 10:00and act as tiny hydroponic gardens for algae,
188. 10:03and they also attract a host of invertebrates.
189. 10:06So they are their own slow-moving, miniature ecosystem.
190. 10:10They become one with the trees.
191. 10:13And we think that their movements are so slow,
192. 10:16they slip under the radar of the monstrous harpy
193. 10:18as it's flying about the canopy, scanning for action.
194. 10:23Sloths are stealth ninjas,
195. 10:25and they rarely leave the safety of the canopy --
196. 10:28except to defecate,
197. 10:30which they do about once a week at the base of a tree.
198. 10:34Now, this risky and energetic behavior has long been a mystery,
199. 10:38and there are lots of theories as to why they do it.
200. 10:41But I think they're leaving surreptitious scented messages for potential mates.
201. 10:48Because, you see, sloths are generally silent, solitary creatures,
202. 10:53except for when the female is in heat.
203. 10:56She will climb to the top of a tree and scream for sex.
204. 11:01In D-sharp.
205. 11:02(Laughter)
206. 11:04Don't believe me?
207. 11:07(Sound of sloth scream)
208. 11:09D-sharp.
209. 11:11This and only this note will get the male's attention.
210. 11:14It mimics the sound of the kiskadee flycatcher.
211. 11:16So the female remains covert,
212. 11:18even when yodeling for sex at the top of her lungs.
213. 11:22Her clandestine booty calls will carry for miles across the canopy,
214. 11:27and males will beat a slow path towards her.
215. 11:30(Laughter)
216. 11:35I think scented messages in her dung will help send Romeo up the right tree
217. 11:40so that he doesn't waste precious energy scaling the wrong one.
218. 11:44Sex, by the way, is the only thing that sloths do swiftly.
219. 11:48I've seen them do it in the wild,
220. 11:49and it's over and done with in a matter of seconds.
221. 11:53But then, why waste precious energy on it,
222. 11:56particularly after that journey?
223. 11:58(Laughter)
224. 11:59Unlike other mammals,
225. 12:01sloths don't also waste time maintaining a constant warm body temperature.
226. 12:06Energy from the sun is free,
227. 12:08so they bask in the sun like lizards
228. 12:10and wear an unusually thick coat for the tropics to keep that heat in.
229. 12:15Sloths have a freakishly low metabolism.
230. 12:19And we think that this might be one of the reasons
231. 12:22that they can sometimes recover from injuries
232. 12:24that would kill most animals.
233. 12:27This sloth recovered from a double amputation,
234. 12:30and I've known sloths that have managed to survive
235. 12:34even power line electrocutions.
236. 12:36And we now think that a low metabolism may well be key to surviving extinction.
237. 12:42Researchers at Kansas University who were studying mollusks
238. 12:46found that a high metabolism predicted which species of mollusk
239. 12:50had gone extinct.
240. 12:53Sloths have been around on this planet in one shape or another
241. 12:56for over 40 million years.
242. 12:59The secret to their success is their slothful nature.
243. 13:04They are energy-saving icons.
244. 13:09And I founded the Sloth Appreciation Society
245. 13:11to both promote and protect their slow, steady, sustainable lives.
246. 13:18I'm a pretty speedy character.
247. 13:21I'm sure you've guessed.
248. 13:22And the sloths have taught me a lot about slowing down.
249. 13:26And I think that the planet would benefit
250. 13:29if we all took a slowly digested leaf out of their book.
251. 13:34How about we all embrace our inner sloth
252. 13:38by slowing down,
253. 13:40being more mindful,
254. 13:41reducing wasteful convenience,
255. 13:44being economical with our energy,
256. 13:47recycling creatively
257. 13:49and reconnecting with nature.
258. 13:52Otherwise, I fear,
259. 13:55it will be us humans that turn out to be
260. 13:58"the stupidest animals that can be found in the world."
261. 14:03Thank you very much.
262. 14:05May the sloth be with you!
263. 14:06(Applause)