Wild salmon senses - reading assignment and an activity
Wild salmon can see, hear, smell, taste and feel. The text below gives you an insight into what the wild salmon's senses are like. The activity challenges you to use senses other than sight.
Competency goals for grade 7, Science
- explain how organisms can be divided into main groups and give examples of the characteristics of different organisms.
- explain some of the body's organ systems and describe how the systems work together.
Look closely at this image of the side of a wild salmon. In the middle you see a kind of line. This is the lateral line organ that the salmon can feel with. Read about the sense of touch further down the page. Photo: Eva B. Thorstad
The wild salmon's senses
The wild salmon has the same senses as you, but they don't work in quite the same way. The wild salmon has no eyelids, it has no ears on the outside and its nose is only two holes.
Syn
Imagine if you had your eyes where your ears are. What would it be like to see then? The wild salmon's eyes are located on either side of its head. They can see forwards, backwards and sideways without turning their heads. The eyes are independent of each other. This means that wild salmon can look forwards with one eye and backwards with the other eye at the same time. They do not have eyelids. The water keeps the eyes moist and clean. Fish can see colors and are usually nearsighted.
Hearing
Even though we can't see the ears of wild salmon, they can hear. They have inner ears. Splashing in water is very audible to wild salmon. Sounds that pass through the air are hard to hear. The wild salmon's inner ear is located in the head. The earstones are small, loose bones inside the ear that help the wild salmon to both hear and keep its balance. You can talk at the river's edge without disturbing the wild salmon, but if you trample the boat, it can hear you well.
Sense of smell
On the fish's head, there are two olfactory pits located in front of the eyes. This is the nose. The fish has a very good sense of smell. The sense of smell is important for finding food. But wild salmon also use their sense of smell to find their way back to their natal river to spawn. As it approaches the coast, it can smell its way back to the river it grew up in and all the way up to the place in the river where it was hatched.
Sense of taste
Wild salmon can sense taste. The taste organ is located in the mouth.
Sense of touch
Along the sides of the wild salmon there is a line. This is the lateral line, a special organ that only fish and some amphibians have. The lateral line has many small holes that detect movement and pressure changes in the water. The lateral line is useful for detecting danger and finding food.
Many people wonder whether salmon feel pain when they bite the hook. We know that salmon can feel pain, but what we don't know is how this pain is experienced.
"Silent hunting" - an activity
"Silent hunting" challenges you to use senses other than sight. We pretend that a trout is chasing a baby salmon. Visibility is poor in the river on this day, so both the trout and the baby salmon must be blindfolded.
The class stands in a circle and holds hands. The ring is the hunting area.
Choose a trout and a baby salmon. Both are blindfolded. Spin them around and place them slightly apart in the ring.
The hunt is on. The trout must use smell and hearing to find the baby salmon. The baby salmon must do the same to stay safe.
Everyone must be quiet and follow the hunt.
Learn about your senses
Watch the movie
For the teacher
Adult trout eat small fish, including young salmon. The activity is a silent game that is quite exciting! If the game is played on a surface that muffles the sound, it can take a long time before the baby salmon are caught.
You can vary the game in different ways. For example, try using several trout at the same time or several baby salmon.
It is also possible to play the game with a baby salmon that is easier to catch. For example, move the action in the game to the sea. The salmon pup, which is now a smolt on its way to the sea, can get too many salmon lice. The smolt is then weakened and is easier prey for predators in the sea. Hang a bell on the salmon smolt, or put a rain jacket on the smolt that makes a sound. Does it make the hunt easier for the predator?
Student booklet
The Nasjonalt villakssenter works for a stronger wild salmon and wants to promote the stream as an educational resource. Bring experiences from the classroom and put them in context with experiences outside. Many schools in Norway have a local stream. Even in our largest cities, there are streams that can be visited. Contact us for assistance, tips and professional support.
The student booklet "Who lives in your river?" can help with both preparation and follow-up work.