Tonic Immobility

Tonic immobility is a reflex that causes a temporary state of inactivity in an animal. Similar to hypnosis.

It occurs in a variety of different species, including many sharks and rays. This trance-like state can occur naturally. It can also be induced in sharks and rays by stimulating the tiny sensory pores located on their snout.

Tonic immobility is often used by researchers when handling sharks to subdue them. Whether in the wild, captivity, or a laboratory. Subduing them minimises their struggling and reduces the possibility of injury. When the shark is gently turned on their back, it’s thought to disorientate them, causing them to enter the state. The shark’s muscles relax and their breathing becomes deep and rhythmic. When released the shark snaps out of this state.

But why would tonic immobility be useful for sharks? Perhaps it’s a defence strategy? Playing dead could deter potential predators. But some shark species that enter tonic immobility are apex predators. So, don’t have many natural predators. They also don’t appear to enter tonic immobility in response to fear. Some scientists suggest it may be related to mating but nobody knows for sure.

We’ve still got a great deal more to learn!

Sharks usually enter tonic immobility in less than a minute. If undisturbed they can remain like this for up to 15 minutes.

Tonic immobility has been used to help test the effectiveness of chemical shark repellents.

SHARKS AND ORCAS

There's evidence to suggest that orcas use tonic immobility to prey on sharks.

In 1997, an Orca in the Farallon Islands was seen holding a White Shark upside down for 15 minutes. Whether intentional or not, the Orca likely caused the shark to enter tonic immobility. Defenceless, the shark, suffocated. This also happened again in 2000.

In New Zealand, Orcas also seem to use tonic immobility to hunt stingrays. Before attacking the orcas will turn themselves upside down. Then, holding the stingray in their mouth, they'll quickly right themselves. Flipping their prey upside down.

Love Discovering Sharks?

Why not join us today? As a member you'll receive our Shark Focus Magazine twice a year. Keeping you up to date with all the latest news about sharks and their conservation!

Join Us

General Donation

You can set up a regular, or one-off, donation in support of all our work. Your gift to sharks will then be allocated where it's needed the most. Every penny helps.

Latest

CREATURE FEATURE: DUSKY SHARK

This month we’re taking a look at the Dusky Shark, a highly migratory species with a particularly slow growth rate and late age at maturity.
Shark Month @ Royal William Yard

Shark Week is a renowned cultural phenomenon – but Plymouth is going bigger and better this summer by welcoming Shark Month to Royal William Yard this July.
#TeamSHARK take on Plymouth Half Marathon 2024

We work in shark conservation because a 1/3 of all sharks and rays are threatened with extinction. If we are able to do more, we can make sure they have a positive future! By donating, you are supporting the important work we do for sharks and rays!!
Stokes Sisters Run for Sharks

Sharks and rays are amazing. Present in our seas for 400 million years, they are vital and valuable but also vulnerable. 1/3 of all shark, skate, ray and chimaera species are threatened with extinction, largely due to the impact of unsustainable fisheries. The Shark Trust works tirelessly around the World to ensure sharks and rays are suitably protected. That's why I'm helping the Shark Trust to safeguard their future with this fundraiser. Together we can create positive change.

Shark Evolution

Most scientists believe that sharks came into existence around 400 million years ago. That's 200 million years before the dinosaurs! Find out more about the history of sharks...
Shark Taxonomy

Taxonomy is a field of science that involves classifying and naming species. It's integral to wildlife conservation, providing the bedrock for our understanding of sharks.
Shark Anatomy

Sharks have a range of adaptations that make them perfectly suited to their environment. It's no wonder they've gained a reputation for being some of the most impressive and formidable predators on the planet!
Shark Senses

Many shark species have brains as complex as mammals, which enables them to process a wide range of senses. Sharks have the same 5 senses as we do plus a couple more...
Male & Female Sharks

How do you tell the difference between a male and female shark? Click here to find out about physical and behavioural differences, as well as shark courtship...
Shark Reproduction

Sharks invest a lot of energy into producing a few, well-developed young. There are 3 main methods of reproduction: oviparity (egg-laying), ovoviviparity and vivparity (live birth).