The Pacific Lamprey

Lampreys are one of the first kinds of fish to evolve, first being found around 450 million years ago, and they have barely changed since then. There are a few different kinds of lamprey, but today I will tell you about pacific lampreys. Pacific lampreys are found around the Pacific Rim, as far south as Mexico and as far north as Alaska. They are parasitic, using their large mouths to latch on to fish and rasp a hole in the side of them with their tongue to drink blood. You have probably heard of lampreys from them invading the Great Lakes, but did you know that in addition to the invasive sea lamprey there are four native species of lamprey found there, two of which aren’t even parasitic! In fact the majority of fresh water lamprey species aren’t parasitic. However, the pacific lamprey that I have been talking about is parasitic and is not in the Great Lakes.

Lampreys are a scaleless, boneless fish resembling an eel, but are more closely related to humans than to eels. Their closest relative is called a hagfish, which is shown below. They are unlike other fish because they lack paired fins, vertebrae and a swim bladder.

They swim like a snake moves, by undulating side to side, or by clinging to things and shooting forward. They have only one nostril that sticks straight up out of their heads. It may seem that they use their teeth to eat, but actually the only thing they use them for is to grip on. The thing they actually use to cut holes is their tongue.

Pacific lampreys are anadromous, which means after a few years in the ocean adults come back to freshwater to spawn, don’t eat for the entire migration, and then die, similar to salmon. After the eggs hatch, the babies, called Ammocoetes, drift downstream for a bit before burying themselves in silt and being a filter feeder for 3-7 years. Once they emerge they head toward to the ocean. Once they reach the ocean they begin to develop teeth to feed on fish. Unlike salmon, pacific lampreys do not go back to the stream where they were born, instead they just pick any suitable spawning stream.

The first time I saw a lamprey was on River Monsters. There was an episode about invasive species, and one of the animals featured on the show was the sea lamprey. The rest of the show mostly featured how much damage the sea lampreys were doing, and not really on anything else about them, which is understandable as that was the topic of the show. However, because of that I mostly forgot about them until we visited a dam and looked at their fish ladder, which was full of pacific lampreys migrating to their spawning grounds. It was really cool looking at all of them latched on to the glass, and thus my interest was reborn.