A hydrodynamic sensory antenna used by killifish for nocturnal hunting

Abstract

SUMMARYThe perception of sensory stimuli by an animal requires several steps, commencing with the capture of stimulus energy by an antenna that, as the interface between the physical world and the nervous system, modifies the stimulus in ways that enhance the animal's perception. The mammalian external ear, for example, collects sound and spectrally alters it to increase sensitivity and improve the detection of directionality. In view of the morphological diversity of the lateral-line system across species and its accessibility to observation and experimental intervention, we sought to investigate the role of antennal structures on the response characteristics of the lateral line. The surface-feeding killifish Aplocheilus lineatus is able to hunt in darkness by detecting surface capillary waves with the lateral-line system atop its head. This cephalic lateral line consists of a stereotyped array of 18 mechanosensitive neuromasts bordered by fleshy ridges. By recording microphonic potentials, we found that each neuromast has a unique receptive field defined by its sensitivity to stimulation of the water's surface. The ridges help determine these receptive fields by altering the flow of water over each neuromast. Modification of the hydrodynamic environment by the addition of a supplemental ridge changes the pattern of water movement, perturbs the receptive fields of adjacent neuromasts and impairs the fish's localization ability. On the basis of electrophysiological, hydrodynamic and behavioral evidence, we propose that the ridges constitute a hydrodynamic antenna for the cephalic lateral line. Supplementary material available online at

Surface tension dominates insect flight on fluid interfaces

“…We speculate that an advantage of such fast locomotion is to avoid underwater predators like fish, which have been known to detect capillary waves on the surface of a pond generated by trapped insects that fall on the fluid surface (Schwarz et al, 2011). We have shown that manoeuvres in the transition between different flight modesinterfacial, airborne and backward -are controlled by postural changes.…”

Detection of artificial water flows by the lateral line system of a benthic feeding cichlid fish

“…For example, the mottled sculpin, Cottus bairdi, demonstrates an orienting response to free-swimming prey (Hoekstra and Janssen, 1985), and responds to a dipole stimulus generated by a vibrating sphere . The striped panchax (Aplocheilus lineatus, a killifish) detects and reorients towards the source of surface waves generated by an oscillating probe (Bleckmann et al, 1981) or a small, falling pellet (1 mm diameter; Schwarz et al, 2011). Similarly, blind cavefish (Astyanax mexicanus) swim toward surface disturbances generated by falling clay particles in cave pools or by a vibrating rod in the laboratory, while the sighted surface-dwelling form of this species rarely exhibits these behaviors in darkness (Yoshizawa et al, 2010).…”

Feeding in the dark: lateral-line-mediated prey detection in the peacock cichlid Aulonocara stuartgranti

“…Nevertheless, the presence of morphological and physiological specializations of individual sensory systems (e.g. Livingston, 1987;Schwarz et al, 2011) is traditionally used as an indication of the enhancement of behavioral capabilities. This correlation provides evidence for adaptive evolution, but the link between sensory morphology and prey detection behavior is not always clear.…”