Science is messy. It’s just a fact. The study of salmon is no exception, especially when it comes to what’s inside. Many people never bother to look past the fillet, but there’s so much more to these fish than that! With the help of longtime volunteer and dissection artist Chris Brown and fellow AmeriCorps member Keelin Maurmann, my mission in October was to bring salmon anatomy into the classroom. Our Junior Stream Stewards spent the month squealing with both delight and disgust as they watched us cut into salmon and reveal the structures within. By the end of the lesson, most students were unfazed by our bloody hands and eager to touch the fish and its organs for themselves.
You might be surprised how much you have in common with a salmon. Stomach, liver, spleen, and brain are all organs that can be found in both salmon and people. Many shared structures have different adaptations however. For example, salmon have no eyelids. When you live in water, there’s no need to blink to keep your eyes moist! Plus, having their eyes on the sides of their head gives them the best chance to spot predators and prey alike. Another similar organ is the heart. While a human heart has four chambers and is located in the chest between the lungs, a salmon heart has only two chambers and is located between the gills. This allows the fish to efficiently pump its blood out of the heart, through the gills, and on to the rest of its body.
Students love guessing about the function of body parts unique to salmon. Every salmon has a large air filled sac in the middle of their body that is often a surprise to students. Don’t be fooled, it isn’t a lung. This is the swim bladder, which helps fish maintain the correct buoyancy in the water. Another cool structure, and one of my personal favorites, is the gills. Just as we use lungs to take oxygen out of the air, fish use gills to take oxygen out of the water. Up close, the gills look and feel like stacks of dark red feathers. All that surface area makes it easier to take up oxygen. The gills are very delicate and are protected from the outside by the bony plates of the gill cover and from the inside by the gill rakers, which filter particles out of the water before reaching the gills. And for the squeamish, even the outside of the fish has a unique sensory structure known as the lateral line. Often a clearly visible dark horizontal line down the side of a fish’s body, the lateral line is made of specialized scales and pores that feel vibrations in the water. These are just a handful of the salmon’s adaptations to aquatic life.
At the end of the day, the most memorable part of this lesson wasn’t the anatomy itself, but the hands-on opportunity it gave students. Not a single lesson went by without a crowd of eager participants feeling the fish and organs at the end. Some of the students who made the most extreme faces during the dissection became the most excited to touch the fish. After all, how often do you have the chance to hold gills? I’m glad I was able to help students see salmon in a new way, but I mostly loved simply getting my hands dirty with them in the name of science!
Special thanks to Chris Brown for teaching me everything I needed to know to lead salmon dissections. And a huge thanks to our sponsors, Fidalgo Fly Fishers, Tulalip Tribes, Samish Indian Nation, WDFW- ALEA Grant, Island Adventures, DOE Clean Samish Initiative, Swinomish Indian Tribal Community, Skagit County Clean Water Fund , and Mountaineers Foundation for making this and other incredible activities possible through their generous support of Junior Stream Stewards!