What is Ancient Jawless Fish: Evolution of Lampreys and Their Arrival in Oregon

What is Ancient Jawless Fish: Evolution of Lampreys and Their Arrival in Oregon

1. What are ancient jawless fish?

• Ancient jawless fish belong to a group called Agnatha (“without jaws”).

• They are some of the earliest vertebrates, appearing more than 500 million years ago in the Cambrian and Ordovician periods.

• Instead of jaws, they had round, sucker-like mouths, sometimes lined with keratin “teeth.”

• Many were covered in bony armor plates (like ostracoderms), while others were more eel-like.

• Today, the only living jawless fish are lampreys and hagfish.

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2. Jawless fish with razor-sharp teeth in Oregon

This likely refers to sea lampreys (Petromyzon marinus).

• Appearance: Sea lampreys are eel-like, jawless fish with a circular mouth full of sharp, keratinized teeth. They use this to latch onto other fish and suck their blood.

• Ancient lineage: They are considered “living fossils” because their body plan has changed very little since ancient jawless fish of the Devonian period (~360 million years ago).

• Arrival in Oregon:

  • Sea lampreys are native to the Pacific Northwest, including Oregon rivers like the Columbia and Willamette.

  • They have lived there for millions of years, long before humans arrived.

  • However, in the Great Lakes region (not Oregon), sea lampreys were invasive, arriving in the early 20th century through shipping canals. They devastated local fish populations.

  • In Oregon, they are actually ecologically important, not invasive. They provide food for wildlife, help cycle nutrients, and are significant in Indigenous cultures.

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3. Why they seem “ancient and terrifying”

• The toothed, suction-cup mouth looks like something out of a horror movie.

• They are among the oldest vertebrate designs still surviving.

• Their feeding method (boring into fish and sucking blood) is gruesome compared to modern fish.

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✅ In summary:

The “ancient jawless fish with razor-sharp teeth” you’re asking about is the sea lamprey. It is a living descendant of early jawless fishes, native to Oregon rivers, and has existed for hundreds of millions of years. While invasive in other parts of North America, in Oregon it is a natural and vital part of the ecosystem.

Also show you a visual timeline of jawless fish evolution leading to the lamprey, so you can see how ancient they are compared to modern fish? 

 

Diagram comparing lampreys to their ancient armored relatives (ostracoderms) so you can see the difference?