Marine fish swim forwards, but can they also swim backward? That’s what we’re going to find out in this article!
The term “fish” usually refers to animals that live in the water such as fish, jellyfish, and starfish.
Some species of fish can move backward by undulating their bodies from side to side and use a technique known as ‘craning’ of their body (the head is slightly above the tail).
This fish then swims backward, but they can only do so for a few seconds.
Caste-like behavior is observed in some species of fish when they respond to stress by swimming backward.
It has been recorded that fish performed this behavioral trait after the death of another individual of the same species.
The fish will swim backward to avoid any possible danger and to escape from predators.
Can fish swim backwards?
Let’s find out…
Can Fish Swim Backwards?
The answer is yes! I think the reason why this is an interesting question, is because it seems to defy the natural laws of nature.
Although this behavior has been observed in some species of fish, there has not been one recorded case where a fish has been observed swimming backward for longer than a few seconds.
One theory for why this is so is that perhaps the forces exerted by water are too great to allow any creatures to swim backward.
This question could be answered by just observing the nature of water.
If you have ever been swimming and tried to move in the opposite direction of where you feel a current pulling, then you will notice that it is impossible.
Water is denser than air and much harder to move against. The longer a fish tries to swim backward, the more that it will start to sink. In most cases, fish will quickly give up attempting to swim backward.
Can All Fish Swim In Reverse?
The answer is a resounding NO! Most fish do not swim backward very well because of the nature of their bodies.
To move backward, the muscles must be stronger than the ones used to move forwards. This would require a stronger muscle that would make it harder to move forward and harder to swim backward.
Evolution has therefore selected some species that can swim both ways (because they can survive) but are unable to expand their range of movements in any other direction.
In most species, the direction that which the fish swims is dictated by the parts of the body that are used to swim.
For instance, fish with large mouths will use only their mouths to swim and consequently mainly swim forwards.
Fish without mouths, however, do not use only their mouths to swim and consequently mainly swim backward.
Some species of fish have never been observed swimming backward in cases where they have been studied.
Whether they can or cannot do it, depends on how long a particular individual has been observed swimming backward.
How Can A Fish Swim Backwards?
It is well known that fish swim forward by undulating their bodies and using their tail to propel them.
If a fish wants to swim backward, then it will have to move its body in the opposite direction of where its tail is moving.
To do this, the fish must undulate its body in the opposite direction of where it would normally do so.
If the fish is not able to move its body in the opposite direction, then it will have to use another method of moving backward.
It can do this by ‘craning’ its body in a certain way that allows it to move backward.
The cranial undulation technique involves using its pectoral fins together with its mouth so that it can generate more force than it would by using just its fins.
The force generated by this movement is directed toward the gills. As the gill muscles force water into the fish’s mouth, it will have to overcome the resistance of water to breathe.
In this way, the fish can move backward. This is why many fish perform cranial undulations when they are feeling stressed and need to escape from predators or enter a burrow.
Which Species Of Fish Can Swim Backwards?
There have been a few fish species that can swim backward.
In some cases, it has been reported that the fish can move backward for a very short period or even for only a few seconds at a time.
Species that have been observed swimming backward include:
1. Sarcastic Fringehead
This fish is a member of the family called ‘fringefishes’. They are found along the Atlantic coast of North America and have been known to swim backward.
2. The Spotted ratfish
It is considered one of the rarest species because of its ability to thrive in an environment that has very few nutrients and its fragile body makes it highly susceptible to predation.
The spotted ratfish has been seen swimming backward and forwards in a very playful manner.
3. The Opah fish
This fish is found in the Pacific Oceans but is rare to find. It was first discovered in 1879 in the North Pacific Ocean and is characterized by its large eyes, which help it to hunt at night. Its body shape also allows it to swim both forward and backward without any difficulty.
4. The Bluehead wrasse
This fish is unique in that it has been observed performing cranial undulations, but little else. It is normally a small fish with a thin body and long dorsal spines.
The bluehead wrasse is found on coral reefs in the tropical waters of the Indo-Pacific.
5. The Surgeonfish
This little fish has been named for its’ ability to use its head as a surgical instrument for removing parasites from other fishes. It has been observed performing cranial undulations in the Red Sea.
6. The Gudgeon fish
The gudgeon fish is considered a very rare species, yet it has been seen swimming backward in the Bahamas.
They are found in a small area of the western Atlantic Ocean and are characterized by their large eyes, which help them hunt at night.
7. The Tarpon fish
This fish is known as the bronze whaler due to its powerful jaw. The tarpon fish is found in the Atlantic and the Caribbean Sea and it has been observed swimming backward in Florida.
8. The Atlantic Sturgeon
The Atlantic sturgeon is one of the largest fish in the sea, with a body that can reach up to 2 meters in length. It is known as the most endangered fish in the world.
9. The Salmon
Salmon are known to swim backward during their spawning migration.
10. The Tuna fish
The tuna have been seen swimming backward, especially when it is trying to escape from predators.
10. The Angel shark
These fish are said to be able to swim backward and forwards at the same time.
They have been seen performing cranial undulations in the shallows of South Carolina. They normally inhabit tropical waters.
How Far Can A Fish Swim Backwards?
The length of the fish is one of the most important factors in determining how far it can swim backward. Smaller fish have a restricted swimming ability, but larger fish can swim longer distances backward.
When a fish performs cranial undulations, it moves backward at a speed roughly equal to its body length.
However, the speed of a fish that is swimming backward is often less than its body length. For instance, a fish of 1m in length will move backward at a speed of roughly 75cm per second.
The speed at which the fish moves backward is influenced by several factors that include the size of the fish, the surrounding water, and its health and condition.
To swim backward, the fish will have to generate enough force to overcome the resistance of the water.
Many fish have been seen swimming backward, however, it is not known whether they can swim backward for long distances.
They normally use this method of movement when they are feeling stressed or threatened by predators.
The fact that fish can swim backward proves that they are intelligent creatures. They possess the ability to maneuver backward and see what is behind them.
This ability has allowed them to develop an excellent means of escape and survival, especially when they are threatened by predators.
Hi, I’m George – the founder of MarinePatch. I created this blog as marine wildlife has been my passion for many years. I’ve spent over a decade in the marine wildlife industry and spent years out in the field conducting research. In today’s modern world, an online blog is the best place for me to share my findings and reach as many people as possible to help educate and inspire others. Enjoy your time here and you’re welcome back anytime!