What does the lateral line do for a trout holding in current?
It is the fish's flow sensor. The lateral line reads pressure and water-particle motion along the whole body, which is how a rainbow holds station centimeters off a rock in turbulent water without wasting energy — it feels the cushion and the seams. The same organ detects the pressure wave of anything swimming nearby, so a nymph tumbling in the drift or a minnow kicking in dirty water announces itself before it is seen. This is why trout keep feeding confidently at night and in chocolate-milk runoff: vision degrades, the lateral line does not.
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This answer is one piece of a longer lesson — setups, diagrams and the reasoning behind it.
More questions about Lateral Line
Same topic, other species
- How do crappie find a jig in muddy water? — Crappie
- How does the lateral line help a muskie track a lure? — Muskellunge (Muskie)
- How does a perch find my jig before it can see it? — Yellow Perch
- How does the lateral line help a pike hunt? — Northern Pike
- In river current, do smallmouth feed by sight or by feel? — Smallmouth Bass
- How does a walleye find my lure in total darkness? — Walleye