.jpeg)
When you read the word “lamprey”, odds are you have either one of two reactions; one “what is a lamprey?” or two, “ugh, lampreys are gross!” Regardless of your first impressions of this group of fishes, I hope after reading this, you will view this eel-like parasite in a whole new light.
For those unfamiliar with the lamprey family, let me introduce you to them. Lampreys belong to a branch of the evolutionary tree called “jawless fish”. It is in this branch that the backbone evolved, and from fossil findings that date back to over 360 million years ago, we know that the lamprey was one of the first lineages that had this trait. These fossils also show us that the lamprey has remained almost unchanged morphologically since before the age of dinosaurs. Their vertebrae were made from cartilage, and they had the characteristic round sucker mouth with sharp teeth, just like we observe today.
The tooth-filled sucker mouth has been important for the lampreys, as many of the species within this group are parasites. The way they feed is by attaching themselves behind the gills of larger fish, to tear up their flesh, and suck their blood. To do this without contracting any diseases, they need a robust immune system. The lamprey’s immune system is similar to ours, in that it creates antibodies to combat microorganisms, such as viruses and bacteria. However, where the vertebrate immune system including the human uses T- and B-cells, the lamprey uses a different group of immune cells, that are hook-like, and have developed through convergent evolution. This means that when “the Tree of Life” branched, and parted ways into jawed- and jawless fish, the lampreys managed to find their own alternative solution, which is just as complex as our own adaptive immune system.
This is not the only area where lampreys display great complexity, as they are a group of fishes with very varying life histories. While some lamprey species can travel to the ocean to live as parasites, such as the river lamprey, others live in freshwater their entire lives, and never drink a drop of blood. This is true for the brook lamprey, and although the river lamprey and brook lamprey seem quite different at first glance, our research has uncovered that they are far more similar than you would think.
We have created the first whole-genome assemblies for the river lamprey and the brook lamprey. We were able to separate the maternally and paternally inherited DNA, in a process called haplotype resolution, or phasing. When we compared the phased whole-genome assemblies we found a great degree of genetic similarity between the two species. So much so that the same sequences were found in the same chromosomal regions in both fish, across their entire genomes. However, although the river lamprey and brook lamprey are very similar, we also found a significant number of structural differences, and large inversions that separate the two species. Perhaps these are the keys to understand why the river lamprey and brook lamprey lead such different lives?
So, the next time you come across a lamprey, I hope you see past its fear-inducing maw, and think about the complexity of this ancient, amazing organism.