Worm grunts

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Worm charming ( at. Worm grunting ) is a method of earthworms to drive by means of vibrations from the ground in order to collect them.

Approach and dissemination

Methods of driving worms to the surface of the soil by means of vibrations are widespread. The method that has been used in the southeastern United States for generations is called worm grunt in the narrower sense . The worm hunter drives a wooden stake into the earth and sets it in vibration by rubbing a metal rod over its upper end. The vibrations cause earthworms within a radius of up to twelve meters to flee from the ground to the surface.

The collected earthworms are used as fishing bait by the collectors themselves or sold to anglers. A few people even make a living from it. A Worm Gruntin 'Festival takes place roughly annually in Sopchoppy in northwest Florida . You exchange experiences, buy worm grunt T-shirts and choose a worm grunt queen. The worm grunts in the neighboring Apalachicola National Forest became so popular in the 1960s and 1970s that the park administration feared for the existence of the local earthworm species Diplocardia mississipiensis and introduced a permit requirement for worm grunts within the park, which still exists today.

Similar methods, also in connection with competitions such as the Great Canadian Worm Charming Championship and Festival and the Devon Worm Charming Festival , are known as Worm Charming and Worm Fiddling in Canada and England. The vibrations are generated by other means than with worm grunts, and aids such as watering or acupuncture of the soil are sometimes used. There are reports from Germany of processes that use pitchforks stuck in the ground to generate suitable vibrations.

Behavioral explanation

Even Charles Darwin , the had taken place across Europe reports on the removal of worms scarecrows, suspected that the vibrations generated by human hunters similar to those of moles are caused when digging. The behavior of the earthworms is geared towards avoiding the moles, their predators , under all circumstances. Another popular theory, however, suggested that the human-generated vibrations resembled the sound of raindrops falling, and that the worms would flee from the ground to avoid drowning.

East American mole

In 2008, Kenneth Catania at Vanderbilt University was able to prove the correctness of the mole hypothesis and falsify the raindrop hypothesis. Catania initially accompanied worm grunts in their collecting activities and found a very high density of moles in the examined region. He also measured the frequency of the vibrations generated by the worm grunts and found that their frequency, at 80-200 Hertz, corresponded to the noise that East American moles make when they tear up grass roots with their powerful front shovels while digging. It recorded the moles' burial noises, used them to sound the ground, and was able to produce the same escape behavior for earthworms as the worm grunts with their vibrating sticks. He also collected a large number of earthworms, put them in a plant box full of soil, then caught a mole and put it in the plant box as well. When the mole buried itself in the ground, the earthworms began to flee to the surface.

Catania found that an East American mole eats almost its own body weight on earthworms a day; thus the mole is by far the worms' most important predator.

The raindrop hypothesis, on the other hand, is implausible, according to Catania. Worms come to the surface in large numbers even in heavy rainfall, but only when the ground is soaked with water after hours of rain, and not in the first few minutes of a heavy thunderstorm, when the drumming noise of the raindrops is particularly pronounced.

Besides humans, other predators also take advantage of the worms' escape behavior. For example, herring gulls waddle on the ground to lure worms out. The trampling of oystercatchers with both feet and the drumming of lapwing with one foot on the meadow floor can often be observed. Forest brook turtles stomp on the ground to achieve the same effect. Richard Dawkins called this phenomenon that prey animals run high risk of falling victim to other hunters due to their behavior towards the main predator , as the rare enemy effect .

swell

Web links

Individual evidence

  1. ↑ Fiddling for Fish Bait , Mother Earth News, accessed February 8, 2011
  2. ^ The War of Worms , Sunday Mirror , April 28, 1996, online article accessed February 8, 2011
  3. ↑ Darwin, Charles: The Formation of Vegetable Mold through the Action of Worms with Observation on Their Habits. New York 1882: Appleton & Company
  4. ↑ Catania, Kenneth: Worm Grunting, Fiddling, and Charming - Humans Unknowingly Mimic a Predator to Harvest Bait online article at PLOS , accessed March 1, 2011
  5. ↑ The bronze lapwing , description on the Fauna im Pantatal website , accessed on March 1, 2011