Sharks are fascinating creatures that spark both fear and love. These hugely misunderstood fish are unique in many ways, and although sharks are the largest fish in the ocean, they have some major differences from other fish. One of which is the ability to swim backward.
Although sharks can move in any direction, unlike other fish, they can’t swim backward. This greatly limited their movement but has its advantages.
Let’s take a look at a shark’s anatomy and its ability to swim backward.
How Do Sharks Swim?
There are more than 500 species of shark, many of which have anatomy that is specifically adapted to their living conditions; however, there are some aspects that remain true across most of these species.
Most sharks are torpedo-shaped, making them streamlined. To swim, sharks use a side-to-side motion known as undulating.
Their pectoral fins on either side of their body are used as stabilizers and aid in rapid maneuvering.
The tail of most sharks is heterocercal (separated into two lobes, with the upper lobe being larger than the lower).
Because of the different sizes of its tail, the shark can control how its body twists and propels. Control over these two lobes in the tail gives sharks the ability to tune the angle at which they swim finely.
Why Can’t Sharks Swim Backwards?
So if sharks are so well adapted to swimming, why can’t they swim backward?
Sharks can’t swim backward because of their anatomy. Two main adaptations limit a shark’s ability to swim backward – their pectoral fins and the lack of a swim bladder.
One of the biggest limiting factors of a shark’s ability to swim backward is its inability to change the direction of its pectoral fins.
A shark’s pectoral fins are specially designed to aid in maneuvering, stabilizing, and steering the shark; however, most sharks’ pectoral fins cannot change direction.
Without the ability to change the direction of the pectoral fins, the forward thrust from the tail cannot be countered, and therefore the shark will only move forwards.
Some fish have an organ known as a swim bladder. Swim bladders are a buoyancy aid that allows the fish to remain neutrally buoyant in the water.
This bladder is filled with gas which changes the volume of the fish, thus adjusting its buoyancy. The swim bladder also aids fish in swimming forwards or backward.
Gas is added to the bladder to aid forward motion, and gas is released to help the fish sink in a backward direction.
Sharks do not have a swim bladder but are instead slightly negatively buoyant. This means that sharks need to keep swimming to stay neutral in the water.
If a shark wants to sink to the bottom of the ocean bed or float backward, it needs to stop swimming and allow gravity to do the work for them.
Are There Any Sharks That Can Move Backward?
As mentioned, sharks can’t swim backward; however, there are some unusual shark species, some of which can move slowly backward through various means.
Nurse sharks are one such exception. These small sharks spend their time navigating tight corners among rocks and coral reefs. Because of the tight spaces, the sharks often find the need to move backward out of a position.
To do this, Nurse sharks make use of a process known as “pump ventilation.” Water is actively pumped through the mouth and gills. When the water is expelled, the shark uses the added force and its tail to maneuver backward.
Not all sharks use pump ventilation for breathing. Others need to maintain forward momentum to push water through their gills.
This is also why a nurse shark can spend long periods lying still on the ocean floor.
Also known as the long-tailed carpet shark, bamboo sharks can move backward, but it is more of a “walk” than swimming.
Bamboo sharks are capable of moving in any direction by making use of their pectoral fins, pelvic fins, and sometimes their tail; these small sharks are able to crawl along the ocean floor.
That said, this is a slow movement and not their primary means of locomotion.
What Would Happen If a Shark Swims Backward?
When sharks move backward, it’s very slow and for short amounts of time. During these movements, the only effect the shark will experience, other than the backward motion, is its negative buoyancy, ultimately causing it to sink slowly.
That said, if a shark had to move quickly backward (perhaps by being pulled), it stands a chance of “drowning” from the depletion of oxygen.
For some sharks, if they don’t move forwards, they can’t breathe.
What Happens If a Shark Stops Swimming?
As mentioned above, most sharks need to keep swimming in order to push oxygen-rich water through their lungs.
If these sharks stop swimming for extended periods, they could die due to oxygen depletion.
That said, some species of shark have an alternative method of breathing. Some catsharks and nurse sharks use “buccal pumping” (the same as the aforementioned “pump ventilation”) to pull in water through their mouths and over their gills.
This allows these sharks to rest on the ocean floor for long periods without the need to move.
That said, sharks are the ultimate predators of the ocean and therefore need to move to hunt, catch prey, and survive.
If sharks can’t swim backward, how do they stop?
As most sharks need to keep moving to breathe, they don’t often stop. That said, sharks do slow down by reducing the movement of their tails and using their pectoral fins to adjust their angles.
How fast can sharks swim forwards?
The Shortfin Mako shark holds the record for the fastest fish shark in the ocean. This fish can swim up to 60 mph.
On the other hand, the slowest shark (Greenland shark) moves at only 0.76 mph due to its size and cold living conditions.
Can you drown a shark?
Although you would find it near impossible to grab a Great White by the tail and drag it fast enough and long enough to drown it, it’s technically possible.
Pelagic sharks make use of ram ventilation to breathe, so if you prevent this from happening, the shark could suffocate.
Can sharks make a U-turn?
Different sharks have different turning abilities, often closely related to their sizes. That said, thanks to the immense thrust of their tails and strong pectoral fins, most sharks can make sharp turns in little to no time.