Yes, sharks do sleep, even though there was once a theory that sharks could only sleep for a few minutes. Incredibly, some sharks do need to swim all the time. This is so they can breathe properly. Amazingly, sharks do not sleep in the same way that we humans do. However, they do have periods of rest.
This article will take a look at whether sharks sleep, how long they sleep for, and when they sleep.
Sharks do indeed sleep, however, they tend to sleep for very short periods of time. Interestingly, Nurse sharks can sleep in a stationary position, allowing them to get the rest they need.
How do sharks sleep?
This is a question that the science world has looked at many times. Sharks obviously need to rest but it’s not always been clear as to how they do this.
Incredibly, sharks are thought to swim all the time so that they can keep breathing. In other words, they need to ensure that water is always moving over their gills. Amazingly, this is how shark’s bodies receive oxygen. What this means is that sharks need to undertake what is known as “Sleep swimming”.
Sleep swimming is thought to involve some parts of the shark’s brain being less active than others. Incredibly, some studies have shown that the shark’s brain does not control their movement while they’re sleeping.
Amazingly, the shark’s spinal cord coordinates their movements. What this means is sharks can continue to swim while they rest. They can get the sleep that they badly need while also getting the oxygen they need.
Do sharks sleep upside down?
Sharks do not sleep upside down, however, there is more to this question. When a shark is turned upside down, it goes into a state of “tonic immobility”. Interestingly, during this state, the shark’s muscle contractions and breathing start to relax. Great white sharks, however, are thought to less responsive to tonic immobility than other sharks.
How long do sharks sleep?
It’s not yet clear how long sharks sleep for. However, what we do know is that many sharks huddle alongside other sharks who are also sleeping. Interestingly, this is not the case for every breed of shark. This behavior has been detected in Whitetip Reef sharks.
There are also other sharks that sleep when they’re not moving, these are:
- Caribbean reef sharks
- Lemon sharks
- Nurse sharks and
- Wobbegong sharks
These are the breeds of sharks that will rest, often in groups as a means of protecting themselves.
Do sharks move when they sleep
Yes, as we have already seen, sharks are thought to swim all the time so that they can keep breathing. In other words, they need to ensure that water is always moving over their gills. Amazingly, this is how shark’s bodies receive oxygen. What this means is that sharks need to undertake what is known as “Sleep swimming”.
What this means is that some specific parts of the shark’s brain are less active than others. Incredibly, some studies have shown that the sharks’ brain does not control their movement while they’re sleeping. This is likely to ensure the brain gets as much rest as possible.
Amazingly, the shark’s spinal cord works to coordinate the movements. What this means is sharks can continue to swim while they rest. They can get the sleep that they badly need while also getting the oxygen they need.
When do sharks sleep?
Some scientific evidence suggests sharks sleep during the daytime. However, some species of sharks sleep whenever they wish. This typically tends to be when they have had plenty to eat and they feel safe.
If you wish to enter shark-infested waters, the safest time is during the daytime. Amazingly, this is because sharks typically hunt at sunrise or sunset.
How do sharks protect themselves while they are sleeping?
Some scientific evidence has suggested that sharks enter a deep resting cycle. Incredibly, when this happens only half of their brain is active.
Additionally, sharks can protect themselves while they sleep as their eyes are always open. Interestingly, sharks do not have eyelids which means they cannot close their eyes. However, there is a translucent membrane that can cover the eyes. This covers the shark’s eyes before they bite their prey.
What types of sharks do not sleep?
Many sharks that live in the pelagic region sleep. The pelagic region is the area of the ocean that isn’t near the coast or near the seafloor. These sharks do not appear to sleep.
Scientists call sharks such as these “Obligate ram ventilators”. What this means is they inhale water through their mouths and ram the water right through their gills. However, these sharks are likely to get some form of rest, but it is not yet clear how.
What type of sharks sleep?
Those sharks that do sleep include:
- Great white sharks
- Hammerhead sharks
- Mako sharks
- Megamouth sharks
- Thresher sharks and
- Whale sharks
As we have already seen, some studies have shown that the shark’s brain does not control their movement while they’re sleeping. This is probably to ensure the brain gets as much rest as possible.
Amazingly, the shark’s spinal cord coordinates their movements. What this means is sharks can continue to swim while they rest.
Some sharks get brief periods of rest while they are descending to the bottom of the ocean. This is known as “Yo-yo swimming”. Amazingly, they will swim to the surface of the ocean and then rest a little as they descend. However, it is not clear whether the sharks are sleeping as such, or taking a bit of a rest.
How Long do Sharks Sleep For?
It’s thought that some sharks can appear to be stationary for a number of hours. Interestingly, they sleep facing the ocean’s current so that water can make its way through their gills.
Amazingly, some sharks have “Spiracles”, these are small openings behind their eyes. The openings also known as “Nostrils” can pump the sea water over the gills. This is the case, even when the sharks in question are completely still.
Where do sharks sleep?
Some studies have shown that many sharks sleep in either shallow or deep seas. Interestingly, some sharks also sleep on the sandy bottom of the ocean or on a coral reef. Incredibly, others sleep facing the ocean’s current. As we have already seen, this is so sea water can make its way over the shark’s gills.
Do whale sharks sleep
As with many other sharks, whale sharks do not seem to sleep quite as such. Fascinatingly, they do have a period of rest whereby only half of their brain is active. This allows the brain to get the rest that it needs, while also keeping an eye out for danger.
Amazingly, whale sharks sleep when they feel safe or when they have had enough to eat.
What do sharks do when they are not sleeping?
Most sharks eat and cruise around the ocean when they’re not sleeping. Impressively, most sharks spend their time eating fish or plankton, depending on what species they are. However, when they have had their fill of fish, they are likely to find a spot to rest for a while.