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Do Lampreys Attack Humans?

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With interests in science and nature, the author explores topics from a unique and sometimes controversial perspective.

Do lampreys attack humans? Read on to find out this and much more about the lamprey, a strange and frightening "living fossil."

Do lampreys attack humans? Read on to find out this and much more about the lamprey, a strange and frightening "living fossil."

Does the Lamprey Attack Humans?

While they prefer fish and won't come after we humans with nearly the same ferocity as they do aquatic creatures, there are accounts of lamprey attacks on humans.

In one interesting story from ancient times, a wealthy Roman named Vedius Pollio kept a pool with hungry lampreys into which he would throw incompetent servants or anyone else he didn't like so much. Whether this is true or not, even dating back to antiquity, people had some reason to fear a lamprey attack.

Despite this bizarre account, experts suggest these creatures would only attack a human out of mistaken identity. They prefer cold-blooded animals, and we humans simply aren't on the menu.

But on rare occasions, it apparently happens. On the Animal Planet show River Monsters, a long-distance swimmer recounted a story where a large sea lamprey attacked him in open water. If this is true, it's hard not to have this creature on your mind if you swim in water where they are known to lurk.

Swimmer Attacked by Lamprey

What Is a Lamprey?

The lamprey isn't an eel, although it resembles one and is often referred to as such. It's actually a species of primitive, scale-less fish. Like the bizarre Coelacanth, this creature can be considered a "living fossil." It attacks its prey by attaching to it with circular rows of fairly nasty-looking teeth. Like an aquatic vampire, it is a parasite that often leaves its victim lifeless.

One can only imagine the terror of encountering these things in their natural setting and becoming lunch for a creature that seems to have been hand-built by a horror movie producer. They're wriggly, slimy, and very mean-looking, and, given a choice, you may prefer to wrestle a great white shark.

But perception isn't always reality, especially regarding snake-like critters. As humans, we tend to have an oft-unjustified fear of long, snake-like beasts, which means the lamprey has an uphill climb if it wants to earn our affection.

On the other hand, it's a nasty blood parasite that latches onto other fish, sometimes in high numbers. With its jawless mouth, sharp teeth, and rasping tongue, it grinds away bits of its host, leaving a gaping hole when it is done. We can imagine a lamprey attack as a pretty horrible way to check out of this world.

Sounds terrible, but do you really have anything to worry about if you aren't a fish? Do lampreys really attack humans, and should we fear this monster? Or is the danger all in our imagination?

Here's a closer look at this terrifying creature.

The sea lamprey is a horrifying creature, but does it attack humans?

The sea lamprey is a horrifying creature, but does it attack humans?

Where Do Lampreys Live?

There are many species worldwide. A few are found in the United States and Canada.

  • Sea Lamprey: The sea lamprey lives in the open ocean of the North Atlantic and the Mediterranean, the Delaware River, the Great Lakes, and other large North American lakes.
  • Silver Lamprey: The silver lamprey inhabits the Great Lakes and the Mississippi River, Ohio River, and their tributaries.
  • Northern Brook Lamprey: The Northern brook lamprey is found in North America in the Great Lakes region.
  • American Brook Lamprey: The American brook lamprey occurs primarily in the Great Lakes and Mississippi River regions and as far north as the rivers of Alaska.
  • Chestnut Lamprey: The chestnut lamprey is often found in the Hudson Bay, the rivers and lakes of Northern Canada, and the Great Lakes region.

How Big Do Lampreys Get?

According to most sources, these lampreys average about two feet in length, with the largest specimens topping out over three feet. That doesn't sound too bad until you picture a three-foot, razor-toothed bloodsucker lurking in the water's dark as you merrily swim along.

Before we worry about size, we must realize that not all Lampreys are parasites. The American Brook Lamprey and the Northern Brook Lamprey pose no danger to humans or fish. While they reach a creepy half-foot in length or so, as juveniles, they are filter feeders, and as adults, they do not consume nutrition, only living a short time.

But the Sea Lamprey is known to prey on large marine fish, including sharks. Their spread across the Great Lakes region has tipped the balance of power in many areas, as they have decimated the natural predators of the area. For this reason, some consider them a pest and an undesirable species.

The sea lamprey reaches average lengths of about 2 feet, but some specimens can be double that size.

The sea lamprey reaches average lengths of about 2 feet, but some specimens can be double that size.

What Do Lampreys Eat?

Parasitic lampreys attack and latch onto other fish. Using their rows of teeth and tongue, they grind into the host and draw out blood and other fluids. Fishermen often catch fish with circular holes rasped into them from lamprey attacks or even fish with Lampreys still attached.

In the ocean, sea lampreys aren't shy about attacking much larger fish and have latched onto specimens like the massive Basking Shark.

In the Great Lakes, they have destroyed local trout and salmon populations in some areas. When they attack, they often kill their host, and even those victims who survive must spend considerable energy on recovering from their wounds.

At least some lampreys in some areas are a big problem. These guys might be your worst enemy if you are a fish, even a huge one. If this parasitic menace doesn't back down from latching onto a 30-foot behemoth like the basking shark, it is hard to imagine it would think twice about us humans.

The basking shark is a massive creature, and subject to attack by lampreys

The basking shark is a massive creature, and subject to attack by lampreys

Should You Fear the Lamprey?

Getting attacked by one of these beasts as you tread water in a lake or sea is a terrifying nightmare. Several of them coming at you at once is an almost unimaginable terror. But there are a few things to consider and a few advantages humans have over even the biggest fish.

While a lamprey latching onto you would surely be unpleasant, they do their real damage as they grate at their host's flesh for hours, days, or even weeks. As high-level primates, we have opposable thumbs, and most of us are more intelligent than fish. We have the strength and wherewithal to shuck these little monsters off as soon as they grab hold. Even if one does zero in on you, the danger is minimal. Of course, that likely won't make you feel much better at the time!

But what about a situation where perhaps dozens of them attack a single human in deep water? Or, what if there are even larger lamprey species out there that we could not overpower? The mind reels, but fortunately, there are no such documented encounters.

The lamprey is a creepy bloodsucker but ultimately poses little threat to humans. But if you encounter one in the dark waters of a cold lake or ocean, you aren't likely to forget it.


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


Fish expert on June 24, 2020:

I live near lake Ontario in New York where sea lampreys are a huge problem for native game fish popunations.

Obama on November 19, 2019:

All i have ti say is you are wrong, the reaskn they have sucker mouths is for feeding, they attach directly to fish, i have personally seen then do it

Nicole on September 04, 2018:

I just got home from a canoeing trip in the boundary waters canoe area wilderness where my youngest daughter accidentally snagged a nice sized lamprey with crazy looking teeth on lake Agnes. I’ve never seen them before and it’s really a creepy looking fish! I was unaware they existed in the northern lakes until this year. However, it didn’t stop us from going into the lakes to clean off, as there are no other means of washing up, even if there’s an occasional attack on humans.

Tamarajo on January 20, 2018:

I'm presently hanging out by the shore of Lake Superior, as I have done for many years. I had absolutely no idea about these terrifying creatures until a friend told me about them and stumbled on to your article. I will take note from here on out and wear waders in the water. Eek!!

KF on February 09, 2016:

I'm from Ontario, Canada and had an unpleasant encounter 2 years ago at Wasaga Beach. I was making my way out of the water when I felt something brush my foot, I tried to kick it off, but it was still there, so I tried to push it off with my other foot and it felt slimy. Assuming seaweed had gotten wrapped on my foot, I pull my foot up and reached down to pull it off - it was not seaweed and it was clearly attached to my foot. It was about a foot long. I panicked, screamed and grabbed whatever the heck it was as hard as I could, and ripped it off. I ran back to shore and realized my foot was bleeding. It wasn't until I got home and talked to my dad that I even found out what a lamprey was. I won't go swimming at the beach ever again.

cryptid (author) from USA on June 01, 2015:

That is a creepy story! Yikes!

TheBlaggert on May 31, 2015:

Interesting article. In N.Ireland where I'm from, I did a lot of freshwater fishing as a kid (salmon/trout) and one day we saw a pretty huge lamprey. The river is pretty small, around 10-15 meters at its widest point.

We'd never seen one before and I'd say it was around 3 feet long. Over the course of the days fishing we covered about 4 miles of river and every few minutes we'd spot the same lamprey surfacing as if it was following us.

Later a friend found a great spot close to the rivers edge and waded about a metre out, and the lamprey actually surfaced and knocked against his wader with its mouth as if it was attacking him. Needless to say he high-tailed it back onto dry land as quick as he could! Makes you think though. Did it actually follow us or was it coincidence?

They're interesting creatures for sure, and I personally find them creepy as hell

Ben l on March 21, 2015:

Very cool facts and right now I'm watching a movie with lamprey called blood lake

cryptid (author) from USA on March 21, 2015:

Thanks Kristen!

Kristen Howe from Northeast Ohio on March 21, 2015:

Another interesting hub from you, Cryptid. I never heard of a lamprey or the silver basking shark before. Very creepy. Voted up!

cryptid (author) from USA on March 11, 2015:

Lamprey are creepy, Court, but there is really no reason to fear them. I can see how you'd be shaken by that though!

court on March 10, 2015:

i was sitting on a rock in the water and got out of the water. 2 seconds later i saw a lamprey slither/swim to the exact spot i was just sitting at and latch on! ive been so fearful of them since and that experience ruined my favourite swimming spot :p

cryptid (author) from USA on February 21, 2015:

@K: There may be a possibility you are taking this way too seriously. This post, as are most of my others, are meant to be entertaining and to get people thinking about strange creatures and "what if" scenarios. Nothing more to it than that.

K on February 20, 2015:

This was one of the most riddiculous pages I have ever read. Especially amusing is how much you try to hype the Danger of the Lamprey even though you have to admit in the end that such danger is almost non-existent. The only thing pages like this one does is make other species than our own appear as something horrifying and undesireable, not interesting and valuable in their own right and I think that poses a bigger danger to us and the ecosystems that surrounds us than any lamprey does to a human.

CT11231 on September 18, 2014:

At least I don't live in michigan!!

that is where I go for vacation...

cryptid (author) from USA on July 23, 2014:

Hi Jumbo. From my reading it appears they can move freely from host to host as fast as they can swim, which is fairly quickly in normal temp water. They do not appear to be limited once they begin feeding, and can disengage and attach to a new host at will.

jumbo fish on July 22, 2014:

Was wondering how fast can they go from one host to another I've only caught one ice fishing and he wasn't very active granted it was only 20degrees outside. any input on the question would be cool thanks

cryptid (author) from USA on May 27, 2014:

Thanks eubug and Hezekiah!

Hezekiah from Japan on May 26, 2014:

Interesting article. I'd never heard of them before .

Eugene Brennan from Ireland on May 26, 2014:

Interesting and voted up! I must remember not to wear my shark fancy dress costume while venturing out into the water... I don't want to be a victim of mistaken identity....

cryptid (author) from USA on May 07, 2014:

Thanks Peggy! Where would we be without our thumbs and brains? :-)

Peggy Woods from Houston, Texas on May 07, 2014:

What an interesting article! I don't swim where most lampreys are to be found but nice to know that we could undoubtedly survive an unlikely attack by them since we have thumbs and brains. Ha! UUI votes and pinning to my fish board.

cryptid (author) from USA on May 07, 2014:

I agree the risk is very small, but I think the "creepy" factor makes Lampreys something people are going to worry about more than they ought to.

CMHypno from Other Side of the Sun on May 07, 2014:

I saw the River Monsters episode and although there is a risk to humans, it really is very small. It's funny how we stress about being hurt or killed by 'monsters' when more people get killed by domestic animals or mundane objects. There was recently an article in a newspaper over here in the UK that pointed out that more people get killed by farm cows every year than they do by sharks, but I don't know many people who are terrified of seeing a cow in a field

sheilamyers on May 03, 2014:

cryptid: You're so right! Why go through life fearing everything. The only thing I'm a little afraid of in the water are jellyfish. They don't attack on purpose, but I always worry a little I'll swim into one.

cryptid (author) from USA on May 03, 2014:

Thanks Sheila! I agree with your perspective on the sea. Personally, I love the ocean and enjoy swimming and snorkeling. Of course I always have it in the back of my mind that something might be out there, but we can't go through life afraid of everything, right? Even Lampreys!

sheilamyers on May 02, 2014:

Thanks for the great information. I saw that episode of "River Monsters" and learned a few things about lamprey's and now I've learned some more from you. I rarely go swimming anywhere other than a pool, but I don't worry about being bitten by fish if I do. I've heard people are more likely to get struck by lightning than to be attacked by a shark or other marine predator even if there are a lot of them around you. I tend to believe that.