The Terror of the Deep: Sawfishes

Since the dawn of mankind, we have encountered monstrosities that seemingly defy our imaginations. Some have come from legend, such as the stories of dragons or giant sea serpents. Others, however, are very much real.

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Image taken from flmnh.ufl.edu

Deep within the confines of the water lies a creature as ancient as time itself. 56 million years ago, the primitive shark underwent a drastic evolution that would eventually lead to the apex predator we know and fear today. As generations passed, multiple families arose from this evolution, and though nearly all of them are now extinct, one family has survived to modern times.

Schizorhiza stromeri nose fossil with teeth highlighted
Ancient sawfish nose

Among the sailors who have seen them and lived to tell the tale, this family is called “Pristidae“. But for those who have not seen the wrath of this beast, we call them “sawfish sharks.” They can grow up to 24 feet long with an average length of 16.4 feet. Compared to the average banana, which is between 8 or 9 inches, these sawfish are giants.

There are five species currently under the family Pristidae. However, they are all very similar to each other, and further review into their biology may reduce that number. Two of these species, the smalltooth and the largetooth sawfish (Pristis pectinata and Pristis pristis, respectfully) can be found in the United States.

Sawfish can be found in many areas of the globe, inhabiting both salt and freshwter systems as well as tropical and subtropical areas. They are even found in the south coast of the United States, along the coast of Florida.

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Areas of reported sawfish sightings

But are these sawfish truly so terrifying that its name is barely whispered in underground bars, or are they perhaps misunderstood?

The “Sawfish Shark” is a name that actually encompasses a multitude of sawfish species. The name itself is incorrect, as it implies that sawfishes are associated with another equally powerful predator, the shark. There are many characteristics that it shares with the shark, such as the ability to replace their teeth if worn down or lost. This is called polyphyodonty. The sawfish also has many differences with its ferocious cousin. One of the most noticeable features is the gills of the sawfish, which are located on its underside, like a ray.

What is most interesting about the sawfish, however, is the enormous weapon of mass destruction they wield in the front of their heads, or the rostrum. It is made of cartilage, not bone, a common feature between sawfish and sharks. The teeth that run along the sides are made of scales rather than bone, giving it a unique property. These can be replaced if they are chipped or damaged, but if they are completely lost, the sawfish cannot grow them back.

sawfish-rostrum-comparison
Both images taken from flmnh.ufl.edu

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When you look upon its countless teeth and its sheer size, even the saltiest sailor can’t help but feel a shiver in their timbers. But sawfish use their saws for much more than striking fear into the hearts of men.

It can be used for feeding:

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Sawfish having some delicious sushi

(A video can be found during my presentation.)

Sawfish enjoy feeding on small crustaceans and fish, especially those that form schools. It was previously thought that sawfish use their saws as digging tools to pry out tasty prey under the sea bottom. However, after observing a sawfish feeding in captivity, it was found to use its saw as an active hunting tool. By swinging its saw back and forth in quick movements, the sawfish can cut apart its prey without giving it a chance to escape.

But that was not the only surprising thing about the sawfish. If you have ever tried to catch or spear a fish in the water, you know that it is very difficult to do so due to the challenges of knowing where it is and where it will be. The sawfish, on the other hand, does not suffer this same problem.

There is a reason why the sawfish is the most feared predator in the seven seas, and the reason is due to its elongated saw. It is loaded with cells that can detect electrical signals of nearby fish in a three-dimentional space around its saw nose. This allows the sawfish to strike with pinpoint accuracy in any direction.

The saw can be used for defense: The sawfish can swing its nose rapidly to attack any predators or threats it perceives.

Adult sawfishes have very few predators, but when they are juveniles these sawfishes find themselves in a world of terror. Large reptiles, such as crocodiles, as well as large predatory fish, like sharks, often prey on the young sawfishes. Fortunately, sawfish do not give birth to helpless eggs, but to healthy fully developed pups that can swim from danger. This process is described as “ovoviviparous.”

A cool fun fact about the sawfish: newborn pups have saw teeth that are not fully formed so that they do not injure their mother accidentally.

On the presentation, I have given you some examples of how they can defend themselves. Be warned: it is not for the faint of heart.

And, of course, sawfish are famous for attacking Victorian era merchant ships:

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The famous sawfish attack

Well… this is only partially true.

Though they look very fearsome with their wicked toothed blade protruding from their nose, sawfishes rarely attack things larger than themselves. They are primarily bottom dwellers, preferring to feed on fish that they can fit into their small mouths. There are very few reported attacks on humans by the sawfish, and the ones that rarely occur only do so if they feel threatened.

These animals can live for up to 30 years, if they manage to reach adulthood at 10 years. However, the sawfish are facing extinction as they are overhunted for their noses while their habitats are slowly transformed to artificial beaches. Their long sharp noses can often trap the sawfish in fishing nets, where they unfortunately meet their demise. The relatively long development cycle makes them prone to environmental changes, especially ones that affect sawfish in their juvenile state. We have already seen the effects of human actions through the Floridian reduction of the smalltooth and largetooth sawfish (Pristis perotteti). Historically, smalltooth sawfish were found throughout the entire peninsula of Florida. Now, they barely cover the southern tip. In the United States, largetooth sawfish can only be found naturally in Texas. All species of sawfish have now been declared “critically endangered.”

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Caught sawfish – note the size
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This sawfish was later released with no harm

 

 

 

 

 

 

 

 

 

 

In Illinois, you can go and see a species of sawfish known as the Green sawfish, or Pristis zijsron, at the Shedd AquariumThey have named her Ginsu, and although she usually spends most of her time at the back of the tank, you might catch her during feeding time, where she was taught to take food from a long grabber tool.

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Photo of the sawfish sign at the Shedd -David

In conclusion, the previous fears we had of the sawfish may be unwarranted, as the animal poses little to no threat to us. In fact, it may be the opposite, where human influence drives the species into smaller and smaller areas. If this continues, the sawfish may truly become a thing of legend, recorded only in history books and long gone from the sea.

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