Water pumps

We know we’ve posted on lamprey in the past, but we think it’s worth sharing this close-up photo of a Pacific lamprey’s gill ducts. Lamprey are different from most fishes that respire by taking water in through their mouth, passing it over their gills arches and expelling it out through gill slits. Because lamprey spend most of their adult lives attached by their mouths to a host organism, they must respire by pumping water in and out of their gill pouches. By contracting extensive musculature surrounding the gill pouches they can pump water in and out of their 7 pairs of external gill ducts, allowing respiration to occur while they are latched onto their next meal.