06/16/2026
We’re celebrating Pacific lamprey all week by exploring some of their amazing features! Lamprey have seven gills.
Unlike most modern fish that have a single gill covering, lamprey have seven simple structures, called gill pores. Most cartilaginous fish, like lamprey and sharks, have multiple gill slits (vs. a single operculum, or gill covering, which is found on fish with bones, like salmon and trout). These seven gills are a sign that lamprey have been on the planet for a VERY long time!
Their gills work in both fresh and salt water and serve different roles during different stages of their life cycle:
🌊 During their larval, river stage – Gills allow them to breathe, as well as act as filter feeders, pulling water in through their open, jawless mouth and out through their gills.
🌊 During their Juvenile and Adult Stages – Gills are used to breathe in fresh and salt water. When their mouth is sealed on a host, they switch to what is called tidal ventilation. This involves muscular contractions which compress and expand, drawing water in and expelling it back out through the same external gill slits in a back-and-forth, or tidal-like, motion. This allows them to stay attached to their host while still breathing.
Photo Credit: Wild Fish Conservancy, CGowell-20220718-08309
