Tonic immobility facts for kids

Tonic immobility is a natural state where animals become temporarily paralyzed. People sometimes call it animal hypnosis. It's like they go into a trance.

We're not totally sure why animals do this. For some animals, like sharks, it might be linked to mating. For others, it's a way to avoid or scare off predators. This is often called playing dead or thanatosis. Imagine a small animal freezing when a bigger animal is nearby. This can help them blend in or make the predator think they are not worth eating.

Animals can be put into this state without seeming stressed. For example, you can gently stroke a certain part of a lobster's shell. Or you can focus a hen's attention on a line drawn on the ground.

Sharks and Their Trance

Some sharks can enter a special trance-like state. This paralysis usually lasts about fifteen minutes before they wake up. Scientists use this amazing ability to study sharks. For example, they test how well shark repellents work. They also figure out the right amounts to use and how long it takes for the sharks to recover.

Many sharks go into tonic immobility when they are turned upside down. For large tiger sharks, scientists can gently place their hands near the shark's eyes on its snout. This can cause the shark to become still. Scientists think this state might be connected to mating in sharks. Female sharks seem to respond more easily than males. When a shark is in this trance, its dorsal fin (the one on its back) straightens. Its breathing and muscle movements also become calm and steady.

Great White Sharks are harder to put into this state than other sharks. There's an interesting story from California. A female orca was seen holding a great white shark upside down. The orca kept the shark still for fifteen minutes. This caused the shark to suffocate and die. This was the first time anyone saw an orca hunting a great white shark in the wild. Orcas have also been seen doing this to stingrays in New Zealand. The orcas turn themselves upside down, grab the stingrays, then quickly flip over. This flips the stingray, putting it into a trance. This makes the stingray an easy meal.

Chicken Hypnosis

You can "hypnotize" a chicken and put it into a trance. To do this, gently hold its head down against the ground. Then, draw a straight line on the ground with a stick or your finger. Start the line at the chicken's beak and draw it straight out in front of it. The chicken will stay still for 15 seconds to 30 minutes, staring at the line. Some people think this trance is caused by fear. It might be a way for the chicken to pretend to be dead.

The first time this method was written down was in 1646. It was in a book called Mirabile Experimentum de Imaginatione Gallinae by Athanasius Kircher.

How to Hypnotize a Chicken

One way to hypnotize a chicken is to hold it on its back, facing up. Then, gently run your finger down its body. Start from its wattles (the fleshy bits under its beak) to just above its vent. This makes the chicken's feet easy to reach. This is helpful for putting medicine on its feet if it has mites. To wake the chicken up, just clap your hands or give it a gentle nudge.

Another way is to make the chicken feel like it's sleeping. Chickens often sleep with their head tucked under their wing. So, hold the bird gently and place its head under its wing. Then, rock the chicken back and forth softly. Carefully set it down on the ground. It should stay in that position for about 30 seconds. One record shows a chicken stayed hypnotized for 3 hours and 47 minutes!

Trout Tickling

Trout tickling is a fun trick to catch a trout. You gently rub the underbelly of the fish with your fingers. If you do it just right, the trout will go into a trance-like state after about a minute. Once it's in this state, you can easily pick it up and put it on dry land.

Why Scientists Study Tonic Immobility

Scientists use tonic immobility to learn about how animals react to danger. They pretend to be a predator. This makes the animal "play dead" as a defense. The idea is that the prey animal pretends to be dead so it can escape if the predator gets distracted. For example, quail that play dead are less likely to be caught by cats.

To study this, scientists gently hold an animal on its side or back for a short time, like 15 seconds. They might do this on a flat surface or in a special holder. For animals like rodents, they might also gently pinch the skin on the back of the neck. Scientists watch how long it takes for the animal to move. They also record how long the animal stays still. This helps them understand how fearful or stressed an animal might be.

This method has shown that hens kept in cages are more fearful than those in open pens. Hens on higher levels of cages are also more fearful. Hens carried by hand are more scared than those moved by machines. And hens transported for longer times show more fear. Scientists have used this test on many animals, including mice, gerbils, guinea pigs, rats, rabbits, and pigs.