Lateral line

In this oblique view of a goldfish (Carrasius auratus), some of the pored scales of the lateral line system are visible.

The lateral line, also called lateral line system (LLS) or lateral line organ (LLO), is a system of sense organs found in aquatic vertebrates, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial cells, known as hair cells, which respond to displacement caused by motion and transduce these signals into electrical impulses via excitatory synapses. Lateral lines serve an important role in schooling behavior, predation, and orientation. Fish can use their lateral line system to follow the vortices produced by fleeing prey. Lateral lines are usually visible as faint lines of pores running lengthwise down each side, from the vicinity of the gill covers to the base of the tail. In some species, the receptive organs of the lateral line have been modified to function as electroreceptors, which are organs used to detect electrical impulses, and as such, these systems remain closely linked. Most amphibian larvae and some fully aquatic adult amphibians possess mechanosensitive systems comparable to the lateral line.[1]

Due to many overlapping functions and their great similarity in ultrastructure and development, the lateral line system and the inner ear of fish are often grouped together as the octavolateralis system (OLS).[2]


The small holes on the head of this Northern pike (Esox lucius) contain neuromasts of the lateral line system.

The lateral line system allows the detection of movement, vibration, and pressure gradients in the water surrounding an animal, providing spatial awareness and the ability to navigate in the environment. This plays an essential role in orientation, predatory behavior, defense, and social schooling.[3] A related aspect to social schooling is the hypothesis that schooling confuses the lateral line of predatory fishes. In summary, a single prey fish creates a rather simple acoustic pattern while pressure gradients of many closely swimming (schooling) prey fish will overlap; that creates a complex pattern, and accordingly the predator will be unable to identify the individual fish through lateral line perception.[4]

The lateral line system is necessary to detect vibrations made by prey, and to orient towards the source to begin predatory action.[5] Fish are able to detect movement, produced either by prey or a vibrating metal sphere, and orient themselves toward the source before proceeding to make a predatory strike at it. This behavior persists even in blinded fish, but is greatly diminished when lateral line function was inhibited by CoCl2 application. Cobalt chloride treatment results in the release of cobalt ions, disrupting ionic transport and preventing signal transduction in the lateral lines.[6] These behaviors are dependent specifically on mechanoreceptors located within the canals of the lateral line.[5]

The role mechanoreception plays in schooling behavior was demonstrated in a 1976 study. A school of Pollachius virens was established in a tank and individual fish were removed and subjected to different procedures before their ability to rejoin the school was observed. Fish that were experimentally blinded were able to reintegrate into the school, while fish with severed lateral lines were unable to reintegrate themselves. Therefore, reliance on functional mechanoreception, not vision, is essential for schooling behavior.[7] A study in 2014 suggests that the lateral line system plays an important role in the behavior of Mexican blind cave fish (Astyanax mexicanus).[8]

Other Languages
Afrikaans: Sylyn
aragonés: Linia lateral
asturianu: Llinia llateral
български: Странична линия
eesti: Küljejoon
español: Línea lateral
Esperanto: Flanka linio
français: Ligne latérale
հայերեն: Կողագիծ
Bahasa Indonesia: Gurat sisi
italiano: Linea laterale
қазақша: Бүйір сызығы
Кыргызча: Каптал сызыгы
lietuvių: Šoninė linija
lingála: Mopanzí
Nederlands: Zijlijn
日本語: 側線
polski: Linia boczna
português: Linha lateral
română: Linie laterală
Simple English: Lateral line
slovenščina: Pobočnica
српски / srpski: Латерални систем
українська: Бічна лінія
Tiếng Việt: Cơ quan đường bên
中文: 体侧线