Mechanical Factors in the Excitation of the Lateral Lines of Fishes

SUMMARYBlind Mexican cave fish (Astyanax fasciatus) sense the presence of nearby objects by sensing changes in the water flow around their body. The information available to the fish using this hydrodynamic imaging ability depends on the properties of the flow field it generates while gliding and how this flow field is altered by the presence of objects. Here, we used particle image velocimetry to measure the flow fields around gliding blind cave fish as they moved through open water and when heading towards a wall. These measurements, combined with computational fluid dynamics models, were used to estimate the stimulus to the lateral line system of the fish. Our results showed that there was a high-pressure region around the nose of the fish, lowpressure regions corresponding to accelerated flow around the widest part of the body and a thick laminar boundary layer down the body. When approaching a wall head-on, the changes in the stimulus to the lateral line were confined to approximately the first 20% of the body. Assuming that the fish are sensitive to a certain relative change in lateral line stimuli, it was found that swimming at higher Reynolds numbers slightly decreased the distance at which the fish could detect a wall when approaching head-on, which is the opposite to what has previously been expected. However, when the effects of environmental noise are considered, swimming at higher speed may improve the signal to noise ratio of the stimulus to the lateral line.

Section: Introductionmentioning

confidence: 99%

The flow fields involved in hydrodynamic imaging by blind Mexican cave fish (Astyanax fasciatus). Part I: open water and heading towards a wall

Windsor

Norris

Cameron

et al. 2010

“…Narrow canals are ideal for highly turbulent environments, whereas widened canals have increased detection capabilities that are better suited for calmer environments (Klein and Bleckmann, 2015). In addition, widened canals are thought to enhance the ability to perform hydrodynamic-dependent behaviors (Denton and Gray, 1988;Denton and Gray, 1989;Janssen, 1997). For example, many dark-dwelling or night-foraging species have widened lateral line canals (Schwalbe et al, 2012;Schwalbe et al, 2016).…”

Section: Future Researchmentioning

confidence: 99%

Mechanosensory signaling as a potential mode of communication during social interactions in fishes

Butler

Maruska

2016

Signals produced during social interactions convey crucial information about the sender's identity, quality, reproductive state and social status. Fishes can detect near-body water movements via the mechanosensory lateral line system, and this sense is used during several common fish behaviors, such as schooling, rheotaxis and predator-prey interactions. In addition, many fish behaviors, such as aggressive lateral displays and reproductive body quivers, involve fin and body motions that generate water movements that can be detected by the lateral line system of nearby fish. This mechanosensory system is well studied for its role in obstacle avoidance and detection of inadvertent hydrodynamic cues generated during schooling and predator-prey interactions; however, little research has focused on the role of mechanosensory communication during social interactions. Here, we summarize the current literature on the use of mechanosensation-mediated behaviors during agonistic and reproductive encounters, as well as during parental care. Based on these studies, we hypothesize that mechanosensory signaling is an important but often overlooked mode of communication during conspecific social interactions in many fish species, and we highlight its importance during multimodal communication. Finally, we suggest potential avenues of future research that would allow us to better understand the role of mechanosensation in fish communication.

“…also have canal systems covered by thin, soft membranes without any regular system of pores. Studies indicate this morphology increases low-frequency sensitivity of the system and similar to the stingray, may facilitate foraging on small fishes, squid and crustaceans in low light environments (Denton and Gray, 1988).…”

Section: Frequency-responsementioning

confidence: 99%

“…However, because the hydrodynamic force acting on the cupula contains both a viscous and an inertial component, a fluid or boundary layer occurs around the cupula that ultimately influences the mechanical coupling of water and the neuromast (van Netten, 1991). The morphology of pored canals creates a high-pass filter that attenuates low frequencies (Denton and Gray, 1988). In contrast, the underlying compliant skin of non-pored canals may function as a low-pass filter that reduces high frequency 3474 stimulation due to the physical constraints of skin movement.…”

Section: Frequency-responsementioning

confidence: 99%

Test of the mechanotactile hypothesis: neuromast morphology and response dynamics of mechanosensory lateral line primary afferents in the stingray

Maruska

Tricas

2004

The mechanotactile hypothesis proposes that ventral non-pored lateral line canals in the stingray function to facilitate localization of prey that contact the skin during benthic feeding. This study used comparative neurophysiological and morphological techniques to test whether ventral non-pored canals encode the velocity of skin movements, and show other adaptations that may enhance detection of tactile stimuli from their prey. Resting discharge rate of lateral line primary afferent neurons was lower among units from ventral than dorsal canal groups. The ventral non-pored canals had a higher proportion of silent units (31%) than either ventral (3%) or dorsal (13%) pored canals, thus may have an enhanced potential for detection of phasic contact with prey. Primary afferents from pored canals showed response characteristics consistent with acceleration detectors, with best frequencies of 20-30·Hz. In contrast, units from nonpored canals responded to tactile skin depression velocities of 30-630·µm·s -1 from 1-20·Hz, and encoded the velocity of canal fluid induced by skin movement with best frequencies of р10·Hz. Sensitivity of non-pored canals to direct skin depression velocity was 2-10 times greater than to hydrodynamic dipole stimulation near the skin. No morphological specialization of hair cell orientation was found among pored and non-pored canals. These low frequency, tactile response properties support the hypothesis that the stingray's non-pored ventral lateral line functions as a mechanotactile receptor subsystem used to guide small benthic invertebrates to the ventrally positioned mouth.