| Recorded at | July 26, 2022 |
|---|---|
| Event | TED-Ed |
| Duration (min:sec) | 04:39 |
| Video Type | TED-Ed Original |
| Words per minute | 164.45 slow |
| Readability (FK) | 45.5 difficult |
| Speaker | Kenny Coogan |
Official TED page for this talk
Synopsis
In the middle of Florida's Apalachicola National Forest, a bizarre, almost magical scene is unraveling. Sliding a metal strip over a wooden stake, a master summoner is sending deep croaking noises reverberating throughout the area. And, as if in a trance, hundreds of earthworms begin emerging from the soil. What's going on? Kenny Coogan explores the tradition known as worm grunting. [Directed by Martina Meštrović, narrated by Alexandra Panzer, music by Marko First].
| 1 | 00:07 | In the middle of Florida’s Apalachicola National Forest, a bizarre, almost magical scene is unraveling. | ||
| 2 | 00:15 | Sliding a metal strip over a wooden stake, a master summoner is sending deep croaking noises reverberating through the area. | ||
| 3 | 00:23 | And, as if in a trance, hundreds of earthworms begin emerging from the soil. | ||
| 4 | 00:30 | This is worm grunting, also called worm charming or fiddling. | ||
| 5 | 00:34 | It’s a tradition that’s been practiced for more than a century, but its inner workings were a mystery until only recently. | ||
| 6 | 00:42 | Worms collectively undertaking an underground exodus seems especially unbelievable when you consider how vulnerable this makes them. | ||
| 7 | 00:50 | So why is surfacing worth the risk? | ||
| 8 | 00:54 | Over the years, people have proposed a number of imaginative hypotheses. | ||
| 9 | 00:59 | One was that worms were somehow charmed by the noise, like the rats from the medieval Pied Piper legend. | ||
| 10 | 01:05 | Okay, sounds fun, but how would the worms actually become bewitched? | ||
| 11 | 01:11 | Another hypothesis was that worm grunting tickled their bodies, so they emerged to end the aggravation. | ||
| 12 | 01:18 | Whimsical! | ||
| 13 | 01:20 | But worm grunting vibrates the ground’s surface. | ||
| 14 | 01:23 | If worms were evading the vibrations, wouldn't they burrow deeper instead? | ||
| 15 | 01:28 | Perhaps the most popular hypothesis was that worm grunting mimicked falling rain and the worms fled to avoid drowning. | ||
| 16 | 01:36 | In 2008, biologist Kenneth Catania tested this hypothesis, setting up three arenas filled with soil and 300 individuals of the large species of earthworm found in the Florida Panhandle. | ||
| 17 | 01:47 | After an hour of rain, water had pooled at the surface, but only two earthworms emerged. | ||
| 18 | 01:53 | The rest remained buried and healthy. | ||
| 19 | 01:56 | So, unlike those containers, this hypothesis just didn’t hold water. | ||
| 20 | 02:02 | Catania decided to explore another route of inquiry. | ||
| 21 | 02:05 | In 1881, Charles Darwin published his final work, a bestseller that rivaled his most well-known books at the time: “The Formation of Vegetable Mould, Through the Action of Worms, with Observations on their Habits.” | ||
| 22 | 02:20 | Yes, it was literally called that— and it was the culmination of 40 years of earthworm investigations. | ||
| 23 | 02:26 | Within it, Darwin noted that worms sometimes left their burrows when the ground trembled and mentioned an interesting hypothesis: maybe they flee because they believe they’re being pursued by moles. | ||
| 24 | 02:39 | Catania got to work testing this hypothesis himself. | ||
| 25 | 02:43 | He found that Eastern moles had astounding tracking abilities, could eat their weight in worms every day, and were abundant in the Florida Panhandle. | ||
| 26 | 02:52 | When Catania released a single mole into worm- and soil-filled arenas, about 30% of the worms crawled to the surface in the first hour— a markedly different result from the control and rain trials. | ||
| 27 | 03:06 | And when he recorded the vibrations produced by worm grunters and moles digging, their frequencies overlapped substantially. | ||
| 28 | 03:13 | This was it. | ||
| 29 | 03:15 | Over hundreds of thousands of years, these earthworms evolved a behavior that helped them escape a top predator. | ||
| 30 | 03:22 | Aboveground, they were immune to the moles, which usually stayed subterranean. | ||
| 31 | 03:26 | But then humans came along. | ||
| 32 | 03:29 | And, funnily enough, we aren’t even the only ones that take advantage of this behavior. | ||
| 33 | 03:34 | Herring gulls and wood turtles also sometimes drum their feet on the earth to summon worms. | ||
| 34 | 03:39 | So then why does this behavior persist? | ||
| 35 | 03:42 | Scientists think it’s beneficial for a prey species to maintain its adaptations against a more frequent predator, even if it makes it more vulnerable to a rarer one. | ||
| 36 | 03:52 | Many insects, for example, use flight to avoid predation. | ||
| 37 | 03:56 | But painted redstarts take advantage of this: they boldly flash their colorful tail and wing feathers to elicit this response, then catch the insects as they try to fly away. | ||
| 38 | 04:07 | It seems the prey species’ response remains simply because it’s beneficial most of the time. | ||
| 39 | 04:13 | For over a century, humans in the southern US, the UK, and elsewhere have been unknowingly exploiting the worm’s escape response. | ||
| 40 | 04:22 | The current world record for “most worms charmed” was set by a 10-year-old British girl in 2009. | ||
| 41 | 04:28 | Wiggling a fork in the ground and hitting it with a stick, she made 567 worms surface in just 30 minutes. | ||
| 42 | 04:37 | Charming, really. |