They go from fresh water to the open ocean
It may sound unbelievable, but a remarkable lineage began over 450 million years ago and still exists today. The Pacific lamprey is a substantial eel‑like parasite that uses a suction‑cup mouth and sharp teeth to attach to hosts and drink blood. This ancient creature lived in Earth’s waters long before dinosaurs roamed, earning it the status of a living fossil.
The Pacific lamprey, scientifically known as Entosphenus tridentatus, typically reaches about half a meter in length, though larger individuals are observed on occasion. Its body shows a mix of primitive and adaptive features, including a cartilaginous skeleton rather than true bones and a specialized organ on the top of its head that detects light. These traits mark a continuous thread from its jawless ancestors to modern lampreys.
Most commonly found along the northern coasts of the Pacific, this species embodies a remarkable time capsule of life on Earth. Its origins trace back to the Ordovician period, roughly 450 million years ago, which makes it one of the oldest vertebrate lineages still in existence.
What makes the lamprey’s life story especially fascinating is its migratory journey. The species begins life in freshwater rivers and streams, then travels to the Pacific Ocean to mature. The epic migration does not end there, because to reproduce, lampreys must return to the freshwater system where they began. The process involves extensive physiological and morphological changes that help them cope with shifts in salinity as they move between saltwater and freshwater environments.
The ability to transition between distinct aquatic habitats is part of what allows lampreys to complete their life cycle. They rely on chemical cues released by their own larvae to navigate back toward their natal rivers, guiding them through miles of coastline to the streams where they were born. Adults may spawn in several places, yet unlike some other migratory fish, lampreys do not always return to the exact same spawning site.
They feed on blood
Lampreys have a distinctive diet. They attach to their prey with a suction mouth that is ringed with rows of sharp teeth. Once attached, they siphon blood and other bodily fluids from their hosts. While lampreys are known to feed on certain fish such as Pacific salmon and other species, they are not strictly herbivores or carnivores alone; their feeding can also extend to birds and marine mammals when opportunities arise. The act of feeding leaves circular wounds on hosts, yet lampreys rely on their hosts to survive since their own life depends on continuing access to a suitable host.
Across the globe, lampreys are part of a broader group of about 40 species that share a jawless ancestry. This lineage has endured several mass extinction events, reflecting a remarkable resilience and an evolutionary patience that has allowed lampreys to persist through deep time.
In modern diets and studies, lampreys are often cited as a powerful reminder of Earth’s ancient biodiversity. Their fatty tissues carry high caloric value and offer a window into the energy dynamics of ancient ecosystems. Scientists continue to explore their biology to understand how a simple, jawless fish could survive so many drastic planetary changes and what that can tell us about resilience in marine life.
For those curious about the broader environmental context, lampreys contribute to the intricate balance of river and coast ecosystems. Their presence signals healthy migratory passages and intact freshwater habitats, underscoring the importance of conserving river systems that support these ancient travelers as they complete their life cycles.