Like every living creature, however, sharks have weaknesses that can leave them vulnerable. In fact, flipping certain shark species upside down renders them immobile for up to 15 minutes, inducing a trance-like state known as "tonic immobility." Tonic immobility can occur naturally, or it can be brought on purposely.
Sharks do not typically swim upside down. However, they do flip over on rare occasions to assume a position known as tonic immobility, according to the Shark Trust, a U.K.-based non-profit dedicated to promoting shark conservation.
While upside-down, the shark's breathing slows, muscles become lax, and the dorsal fin straightens, rendering it almost helpless.
Flipping a shark—any species of shark or ray—will put the animal in a trance-like state where they become calm and don't struggle as much. It's similar to hypnosis. When in this state, a shark's muscles relax, and they breathe deeper and more consistently.
It may surprise some people to learn that sharks can in fact be made to sleep by turning them upside down. This behavior is known as tonic immobility, and it has been observed in various shark species, including lemon, nurse, bull, and hammerhead sharks.
You may have heard that you can 'hypnotize' large predators like sharks or alligators by rubbing their bellies. There's some truth behind this. Tonic Immobility is a reflex characterized by a state of immobility and apparent paralysis.
Some species are 'hypnotised' when they are turned upside down. Sharks' noses are full of nerve endings, and rubbing them is said to scramble their sensory system.
Made of very strong and thick bone, dolphin snouts are biological battering rams. Dolphins will position themselves several yards under a shark and burst upwards jabbing their snout into the soft underbelly of the shark causing serious internal injuries. More than Peas in a Pod.
Bats. It may not seem like the ideal sleeping position to us, but, for bats, sleeping whilst hanging upside down works. It not only keeps them out the way of predators but it also means they are in the perfect position to fly away if needed.
So, while most sharks will be 100% fine if they stop swimming, a few iconic species such as great white sharks, whale sharks, hammerheads and mako sharks would suffocate without forward motion or a strong current flowing towards their mouths.
If you roll an alligator on its back and hold it there, it will exhibit a strange behavior. After 15 or 20 seconds, the alligator will go limp and become unresponsive. It's called tonic immobility and, for a phenomenon so widespread in the animal kingdom, we know surprisingly little about it.
Myth #1: Sharks Must Swim Constantly, or They Die
Some sharks must swim constantly in order to keep oxygen-rich water flowing over their gills, but others are able to pass water through their respiratory system by a pumping motion of their pharynx. This allows them to rest on the sea floor and still breathe.
When sharks float upside like this its called tonic immobility. It occurs when a shark goes into a trance-like state by a reflex that causes a temporary state of inactivity, it's very rare to catch a shark in this state.
Some sharks such as the nurse shark have spiracles that force water across their gills allowing for stationary rest. Sharks do not sleep like humans do, but instead have active and restful periods.
Megalodons succumbed to global cooling due to the shrinking of their habitat, the vanishing of their favorite prey, and competition from other predators 3.5 million years ago.
Alternatively, divers and swimmers can probably reduce the chance of an interaction with a shark by avoiding bright and highly contrasting swimwear or dive gear. We personally prefer to use dark blue or black fins, mask, tank, and wetsuit while diving.
ESDs aim to overwhelm a shark's electro-sensory system. They emit electrical pulses (each one does so in a different way) that are supposed to repel the shark. So far, ESDs have been the most effective type of personal shark repellent.
What does a shark attack feel like? While each survivor describes the experience differently, a common description from shark attack survivors is the attack feels similar to being punched or bumped. Some survivors have even recounted no pain at all!
Smaller, streamlined species are capable of higher speeds than larger, bulkier sharks like the great white shark. The general rule of thumb is that great white sharks can cruise at about 5 mph (8 kph), the speed of the fastest Olympic swimmer. If you're just a good swimmer, they have you beat.
It is commonly believed that the best way to fend off a shark attack is to punch (or stab, if you can) a shark in its nose, which is especially sensitive. The best bet, however, is to go for the eyes and gills, as Lisewski did.
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?
Decreasing the surface tension and creating a moisture film prevents fogging. So how does Spit help? Saliva acts as a surfactant. Surfactants are wetting agents that lower the surface tension of a liquid, allowing easier spreading.
It is prejudice. Sharks do not circle in the water before they attack, it is simply their way of trying to form an image of what they are confronting in the water. According to my own numerous observations this motion is a sign of pure curiosity and not an incentive to circle its prey and feed.