Morphology and hydro-sensory role of superficial neuromasts in schooling behaviour of yellow-eyed mullet (Aldrichetta forsteri)

Abstract

The lateral line system is a mechanosensory organ found in all fish species and located on the skin or in subdermal canals. The basic functional units are superficial and canal neuromasts, which are involved in hydrodynamic sensing and cohesion in schooling fish. Yellow-eyed mullet (Aldrichetta forsteri) are an obligate schooling species found commonly in shallow coastal areas of New Zealand and Australia. Schooling is a fundamental part of their behavioural repertoire, yet little is known about the structure or functionality of the lateral line in this species. We used scanning electron microscopy to characterise the morphology of trunk superficial neuromasts. We then took a multi-sensory approach and conducted behavioural experiments comparing school structure in groups of fish with and without fully functioning lateral lines, under photopic and scotopic conditions. A highly developed hydro-sensing system exists on the trunk of yellow-eyed mullet consisting of superficial neuromasts containing hundreds of hair cells aligned, with respect to their most sensitive axis, in a rostrocaudal direction. Without functioning superficial neuromasts, schooling behaviour was disrupted under both photopic and scotopic conditions and the ability to detect stationary objects decreased. Results highlight the importance of this component of the lateral line system to schooling behaviour.

The effects of lateral line ablation and regeneration in schooling giant danios

“…A school also helps to position individuals so that they can most quickly respond to their neighbors. For most schooling species, individual fish prefer to maintain a distance of about one body length to their nearest neighbor (Partridge and Pitcher, 1980;Faucher et al, 2010;Middlemiss et al, 2017). Not only do fish swim together and maintain a specific individual distance, but the entire school can perform complicated maneuvers requiring individuals to respond quickly to changes in speed and directions of their neighbors (Partridge and Pitcher, 1980;Chicoli et al, 2014).…”

“…The fact that many species of fish form schools suggests that the behavior offers a clear evolutionary advantage (Greenwood et al, 2013;Kowalko et al, 2013). Yet, we are only just beginning to understand how fish form and maintain schools, and the roles of the lateral line system and vision in this behavior (Partridge and Pitcher, 1980;Pitcher et al, 1976;Faucher et al, 2010;Chicoli et al, 2014;Middlemiss et al, 2017). The lateral line system is composed of a spatial array of neuromast receptor organs located on the head (anterior lateral line) and along the body ( posterior lateral line).…”

“…Disabling the lateral line system, either chemically or surgically, does not prevent fish from schooling, but it does change the position they maintain within a school (Pitcher et al, 1976;Partridge and Pitcher, 1980;Faucher et al, 2010;Greenwood et al, 2013;Kowalko et al, 2013;Chicoli et al, 2014;Middlemiss et al, 2017). Partridge and colleagues (Pitcher et al, 1976;Partridge and Pitcher, 1980) performed a set of experiments in the 1970s and 1980s to test the role of the lateral line and vision in schooling in saithe, Pollachius virens.…”

Effects of group size on school structure and behaviour in yellow‐eyed mulletAldrichetta forsteri

“…The seemingly effortless coordination witnessed in schools of fish (Partridge, ; Couzin et al, ; Krause & Ruxton, ) requires each animal to match the movement of its neighbour instantly, using a suite of sensory capabilities ( e.g . lateral line system; Middlemiss et al, ), resulting in the whole group travelling together as one cohesive unit. The singular appearance of fish groups in various shapes ( e.g .…”

“…: +64 (0) 220656075; email: kombi@xtra.co.nz the movement of its neighbour instantly, using a suite of sensory capabilities (e.g. lateral line system; Middlemiss et al, 2017), resulting in the whole group travelling together as one cohesive unit. The singular appearance of fish groups in various shapes (e.g.…”