AFS 401- Fisheries Practical Manual

Nostrils – Some fish have a well developed sense of smell and use this ability to seek out their home streams for spawning. In some cases, this scent is also helpful in avoiding predators. Fish breathe through their gills, not their nostrils. Lateral Line - Fish do not have ears, as such. In part, low frequency sounds are detected in the water through a system of small holes along each side of a fish called the lateral line, which is connected to a delicate system of nerves. They also react to medium frequencies suggesting they detect these as well (this reaction is not well understood at this time). Mouth - Fish use their mouth to catch and hold food of various types, but their food is not chewed before swallowing, it is swallowed whole. The mouth is the beginning of the fish’s alimentary canal (digestive tract). In addition, it is a very important part of the breathing process. Water is constantly taken in through the mouth and forced out over the gills where oxygen is extracted. 5. Inside the mouth for teeth. Open and close the mouth. Describe how the upper and lower jaw articulates during this movement.